Summary of main results
Studies in this review demonstrate that psychosocial interventions can support women to stop smoking in pregnancy. Importantly, the interventions do not appear to have any negative physical or psychological effects, are positively received by most women, and may improve psychological wellbeing. Incentives had the largest effect size, but only when provided intensively. Counselling was effective when provided in conjunction with other strategies or tailored to individual women, but it is unclear whether any types of counselling are more effective than others. Peer support appeared to be effective, but only when provided as a targeted intervention and not as part of a broader intervention to improve maternal health. It is unclear whether partner-assisted support helps women to quit. Feedback appeared to be effective when combined with other strategies, such as counselling, and compared with usual care, but not less intensive interventions. Health education was not effective in separate comparisons, but the pooled effect was significantly different from zero in subgroup analyses. Among women who received psychosocial interventions there was a significant reduction (18%) in preterm births (less than 37 weeks' gestation), the proportion of babies born low birthweight (18%) (less than 2500 g), and a significant increase in mean birthweight of 41 g. Using data from this review, the NNTB to prevent one infant being born low birthweight is 61 (95% CI 38 to 204); and 71 interventions (95% CI 42 to 341) to prevent one infant being born preterm. These findings provide strong and clear evidence about the risks of smoking during pregnancy, supporting recommendations that it may be an integral part of strategies to reduce preterm births (Green 2005a). Given the benefits of stopping smoking in pregnancy for the woman and her infant, this would seem to be an important intervention, particularly when applied at a population level. However, it remains unclear from dissemination trials whether interventions are effective when implemented into routine pregnancy care.
Among the subgroups of 'main intervention strategies' categorised in this review, the four studies that included use of incentives had the strongest effect. Three trials that compared provision of intensive incentives with usual care (Tuten 2012), incentives and social support compared with a less intensive intervention (Donatelle 2000), and contingent incentives compared with non-contingent incentives (Heil 2008), were significantly different from zero. A three-armed trial, which included a non-contingent arm (Tuten 2012), also showed a significant effect. These non-contingent comparisons provide a 'time-matched' alternative comparison of similar intensity, which helps to identify if it is the 'additional assistance' or incentives which are effective (Mantzari 2012). The effect was also significantly different from zero in the pooled results of three counselling interventions that included lottery tickets (Sexton 1984; Walsh 1997; Parker 2007). These findings are consistent with other reviews of financial incentives in pregnancy (Higgins 2012) and the mechanisms for the effectiveness of incentives for reducing substance abuse more generally has been well documented (Higgins 2008b). However, the results of the incentives trials should be considered with caution as they are based on few trials with a very small number of women (less than 500), all of whom were in the US. Additionally, there was no effect from one trial of 'low intensity' incentives ('CM Lite') combined with an interactive computer-generated counselling program (Ondersma 2012), which relied on women initiating contact with the research team for urine cotinine testing, and provided a maximum of only five verification and 'incentive' interactions, with less than half the women in this arm submitting even one urine test. Interestingly, women in this four-armed trial who received the interactive computer-generated counselling program alone were more likely to quit than women who received the combined incentive and computer-counselling intervention (see Ondersma 2012).
Pooled results of interventions in which counselling was the main intervention strategy showed a significant effect in abstinence in late pregnancy. However, in separate comparisons, the effect of counselling was only significantly different from zero when combined with other strategies or tailored to individual needs. There was no significant difference seen when one type of counselling (cognitive behavioural therapy (CBT)) was compared with traditional health education (Cinciripini 2010), or when counselling was provided as part of a broader intervention to improve maternal health (El-Mohandes 2011). Group interventions were generally not well accepted in this population of pregnant women, despite being reported as a potentially well accepted intervention in the general population (Bauld 2010). Feedback was effective when combined with other strategies such as counselling, and only when compared with usual care. Findings from this review support recommendations that pregnant women may need more support than just brief advice or health education (Coleman 2004), as it was unclear whether health education alone helped women to quit. However, there was a significant pooled effect among the three trials of health education when two studies were removed providing only self-help materials or an audiotape with no additional personal advice, which is similar to findings in another review (Murthy 2010), and which concluded that apart from brief physician advice, there was limited clarity on the duration of interventions required by other professionals.
Social networks have been suggested as a major cause of relapse (Nguyen 2012b), and a systematic review of qualitative studies identified partners as one of the most important influences on women's smoking and relapse (Flemming 2013). In this review, peer support appeared to be effective when provided as a targeted intervention, and when social support was provided as part of a broader intervention to improve maternal health, but not when [telephone] support was compared with a less intensive intervention. It is unclear from the single trial of partner-assisted support (McBride 2004) that this strategy can help women to stop smoking. Furthermore, counselling interventions that included support for partners to quit also did not show a significant effect, and there were mixed results in the four studies reporting associations between quitting and partner smoking. Mixed results have similarly been reported in a systematic review of five randomised controlled trials (Duckworth 2012), and another review of seven studies reported a non-significant effect (Hemsing 2012), concluding that, "Despite the importance of partner smoking, there are very few effective smoking cessation interventions for pregnant/postpartum women that include or target male partners". This raises questions about arguments that a major reason for the modest effect of smoking interventions is the focus on individual behavioural change rather than acknowledging social factors and focusing on external motivation (Okoli 2010). Additionally, feedback from women demonstrates the support from both partners and peers can sometimes be negative, which raises concerns about the potential risks for vulnerable women in physically or emotionally violent relationships. Evidence from this review suggests that while partner and peer support may be important factors influencing smoking behaviour, eliciting peer and partner support that is positive and can actually support women to stop smoking in pregnancy is a challenge.
The lack of a clear difference in effect seen by increasing intervention intensity challenges the validity of the assumption that ever-increasing the intensity of support will increase quit rates, as has been reported by other commentators (Lando 2001), and supports views that there may be an upper limit of what women accept (Chapman 2012). Newly included studies in this review had lower effect sizes than older studies in the previous version, despite a general trend towards higher intensity interventions in more recent trials. It may be that women who continue to smoke are not getting 'more hard core' but that there are many options already available and additional strategies may not be offering a lot of extra benefit, as risks of smoking during pregnancy, due to health education campaigns, are well known in high-income countries (Campion 1994; Eriksson 1996; Eriksson 1998). One study found relapse within the first two weeks was predictive of continued abstinence, and suggested this indicates that intensive support during the earlier period of nicotine withdrawal may be an important component of interventions (Higgins 2006b).
Studies in this review suggest the effect during pregnancy continues into the postpartum period, up until approximately 18 months postpartum, though the smaller effect size shows many women who did quit during pregnancy relapse postpartum. Some suggest that many pregnant smokers simply suspend their smoking for the duration of pregnancy as opposed to quitting altogether or they commit to 'temporary abstinence' for pregnancy (Stotts 1996; Lawrence 2005a; Flemming 2013), but these relapse rates are similar for non-pregnant women (Bombard 2012). Rather than being disappointed by these limited effects, some authors suggest healthcare workers should focus on the positive aspects of these findings and reinforce the positive decisions many women are making when pregnant (Hotham 2008). High post-pregnancy relapse rates have led to some commentators calling for an extension of the period of support for women to stop smoking (Coleman-Cowger 2012). Hjalmarson 1991 reported a high proportion of women abstaining from smoking during their hospital stay for the birth, and suggests this may be an opportunity for intervention to reduce the risk of postpartum relapse. These findings suggest there may be a need for different approaches to promote continued abstinence postpartum, including focusing on the benefits for the mother, without excessive emphasis solely on the benefits for the baby.
While results are mixed, studies in this review suggest there is a reduction in self-reported smoking but not biochemically validated smoking. Continued nicotine and cigarette exposure may have effects on other outcomes not measured in this review. The level of reduction required to improve health outcomes remains unclear (Secker-Walker 2002a). One study analysing data from Kendrick 1995 suggested that reduction in smoking to fewer than eight cigarettes a day is necessary to avoid reduction in infant birthweight (England 2001), and estimated approximately a mean birthweight which was 200 g higher among women who quit smoking after enrolment, compared to women who continued to smoke during pregnancy. Therefore, extrapolating these data to this review, if all women in the intervention groups stopped smoking and none of those in the control group did, the expected mean birthweight difference would be about 200 g, rather than 41 g. With an absolute difference of six in every 100 women stopping smoking, the expected mean difference from the extent of smoking cessation alone would have been about 12 g. This suggests that smoking reduction is also happening to a greater extent in the intervention than comparison groups, in line with self-reported changes.
There was no evidence from studies in this review that smoking cessation increases the rate of caesarean section (Thornton 1997; Cope 2003; Tappin 2005), contrary to concerns raised by women about the effects of increased fetal size (Sexton 1984). One observational study modelled increases in birthweight (from 2450 g to 2550 g) in Guatemala and found an increased risk in caesarean section due to obstruction of eight in every 1000 cases, but this was outweighed by a reduction in caesarean section due to fetal distress of 34 per 1000 cases (Merchant 2001).
Women who smoke are less likely to initiate breastfeeding (Amir 2001a; Amir 2002a; Donath 2004; Einarson 2009; Disantis 2010b), and breastfeed for shorter duration (Sayers 1995; Horta 1997). Therefore, supporting women to initiate and maintain breastfeeding should be considered an important part of any intervention in this population group, and reported as an outcome in intervention studies. Studies in this review had mixed reports of the effect of smoking cessation interventions on breastfeeding (Panjari 1999; McLeod 2004; Higgins 2010b).
Studies in this review (Cinciripini 2000; Rigotti 2006) support a recent qualitative study that concluded "Pregnant women with mental disorders appear more motivated...yet find it more difficult, to stop smoking" (Howard 2013), and other studies that report higher rates of quitting among women with higher self-esteem and self-efficacy (Massey 2013). For these reasons, healthcare workers have reported difficulty addressing smoking with pregnant women (Wood 2008). Qualitative studies have identified concerns about adverse effects of quitting, or increased guilt over continued smoking, on women's psychological wellbeing and capacity to cope with adverse circumstances, with follow-on effects to the women's families (Oliver 2001; Wood 2008; Flemming 2013). In earlier versions of this review, it has been difficult to assess the effect of interventions on depression, as, despite the strong associations with poor mental health and smoking in pregnancy, women with mental illness were frequently excluded from trials. However, mental wellbeing has been addressed in more recent trials and, contrary to the above concerns, there is no evidence from studies in this review that there are any negative psychological consequences from delivery of individual smoking cessation interventions in pregnancy. Rather, feedback from women from studies in this review was positive with women feeling that "somebody cared" (Bullock 1995). Three studies have shown that provision of psychosocial support can in fact improve women’s psychological wellbeing, which has the potential to have enormous benefits for the mother, the infant, and the whole family (Bullock 1995; Stotts 2004; Cinciripini 2010).
In earlier versions of this review, there appeared to be little evidence of the involvement of pregnant women who smoked or caregivers being involved in the design and evaluation of interventions (Oliver 2001). However, there has been increasing discussion of women's preferences for cessation support in recent years (Ussher 2004). Studies included in this review suggest women prefer individual personal contact, particularly by telephone, though studies inclusive of telephone support in this review did not appear to be significantly more effective. Rates of satisfaction with interventions delivered by computers or mobile phones were generally positive, but again there was no evidence in this review that the use of these technologies increased the rate of abstinence in late pregnancy. Nevertheless, acceptability of an intervention is an important aspect of population-based interventions.
Some evidence suggests that women in high-income countries are more likely to smoke to control their weight, and that female body image is extensively targeted by tobacco marketing campaigns (Pomerleau 2000; CDCP 2002; Levine 2006), although concerns about gaining weight through stopping smoking during pregnancy were not raised by any of the women consulted for this review (Oliver 2001). The systematic review of qualitative studies of women smoking in pregnancy (Flemming 2013) found two studies mentioning weight gain as a factor in considering smoking cessation. Hotham 2002 found that fear of weight gain was a barrier to smoking cessation for some women and Lawson 1994 found some women used smoking to cope with weight gain.Three studies in this update of the review (Sexton 1984; Berg 2008; Washio 2011) address weight gain. Only one study reported a small increase in weight gain among women in the intervention group (Sexton 1984). This concern should be considered in interventions, with interventions available to support women to avoid unwanted weight gain (Farley 2012). It should be noted that weight gain in pregnancy may not necessarily be a negative outcome for many women, particularly women in low- and middle-income countries. The association between smoking and glucose intolerance, a potential mechanism for these effects, remains unclear (Wendland 2008). A Cochrane systematic review of interventions for preventing weight gain after smoking cessation mentioned neither pregnancy nor breastfeeding (Parsons 2009) and therefore cannot be relied upon for evidence relevant to a population where weight may fluctuate for normal physiological reasons and where babies may be sensitive to drug treatments in utero or when breastfeeding.
Public health impact of the interventions
Importantly, psychosocial interventions to support women to stop smoking during pregnancy reduce the population-attributable risk of preterm birth (by 18%) and low birthweight (by 18%), with approximately 71 interventions required to prevent one preterm birth and 61 interventions to prevent one infant being born with low birthweight. As such, smoking cessation is recommended as a key recommendation for reducing the risk of recurrent preterm birth (Chang 2012; Cypher 2012). The number of interventions needed to treat for benefit is extraordinarily low, given the serious clinical consequences of these adverse outcomes. Based on the effectiveness published in the 2004 version of this Cochrane review, if 75% of pregnant women in the US disclosed their smoking status and all received the intervention, then it has been estimated that 31,573 (6%) 'new quitters’ would be gained and the prevalence of smoking in pregnancy would potentially decrease from 16.4% to 15.6% (Kim 2009b). While these effect size estimates may appear modest, the response to interventions is similar to that of psychosocial interventions to reduce type 2 diabetes mellitus, hypertension and asthma, all of which are conditions that involve a combination of medical illness, personal choice and environmental factors (McLellan 2000). Importantly, the high prevalence of these conditions in the community means that interventions with a modest effect size estimate can have a substantial impact on population health if widely implemented.
Studies in this review report variable cost-effectiveness measures and costs of interventions. Based on a NNTB of one quitter for each 19 interventions, our cost estimates ($US1,064) based on $US56 per interventions is significantly higher than the $US299 reported in Dornelas 2006. However, even with higher estimates, other studies that evaluated the cost-effectiveness of these interventions clearly show that there is a ‘rapid return on investment’ (Lightwood 1999). Early studies estimated the smoking-attributable maternal costs during pregnancy alone ranged from $US150 million to $US995 million in the early 1990s (Adams 1998), with 2004 estimates of $US122 million or $US279 per smoker (Adams 2011). Estimated birth and first year costs for both mothers and infants attributed to smoking were $1142 to $1358 per smoking woman over a decade ago (Aligne 1997; Miller 2001; Adams 2002). Infant costs are approximately 10 times maternal costs, accounting for 90% of costs in the first year. Low birthweight produces the highest economic burden as it is the most common adverse outcome (Hueston 1994; Miller 2001). A 1% drop in smoking prevalence was estimated to prevent approximately 1300 low birthweight live births and save $US21 million in direct medical costs (Lightwood 1999). Inclusion of smoking attributable and environmental tobacco smoke exposure costs in birth and childhood conditions, pushes estimates into the billions (Aligne 1997), and long-term costs due to chronic disease up to $US57 billion in 1997, in the US alone (Bartlett 1994). An economic evaluation of data provided in the 2009 version of this review estimated the societal benefits from these interventions could be in excess of 500 million pounds sterling per annum in the United Kingdom (Taylor 2009). In contrast with that finding, the quality of diet in pregnancy (in high-income countries) has not been shown to affect the mean birthweight of infants over 32 weeks' gestation (Rogers 1998). While there is variation in reported costs dependent on conditions included and changing healthcare costs (Ayadi 2006), it is clear that healthcare costs due to smoking in pregnancy are substantial.
Impact on health inequalities
In high-income countries, the reduction in rates of smoking has not been as substantial in women experiencing psychosocial disadvantage, as for the general population. Hence smoking has been identified as a major preventable cause of the health inequalities experienced by women who suffer psychosocial disadvantage, including psychological illness, low educational attainment, young early motherhood, lack of social support, and limited employment (Graham 2006). Some of the reasons may be that disadvantaged women are unable to change the environmental factors that increase the risk of smoking; population-based interventions may have the effect of being judgemental and alienate women; and women are unable to change generational patterns (Graham 2009). Several authors have suggested that women who continue to smoke in late pregnancy would be unlikely to benefit from the usual antenatal interventions, which rely on women's capacity for self-initiation, self-control and social resources, which they suggest helps to explain why it remains such an intractable problem (Wakschlag 2003; Pickett 2009) and that individual interventions alone are unlikely to impact on inequalities (Baum 2009). However, subgroup analysis of studies included in this review refutes these arguments and suggests that individual interventions provided during pregnancy have similar effectiveness among women with low socio-economic status (SES), as women who are not classified as having low SES, despite several studies reporting a lower effect among participants with lower SES (Baric 1976; McLeod 2004; Pbert 2004; Rigotti 2006). This supports qualitative studies that suggest individual support, which is positive rather than punitive, has an important role (Bond 2012). Therefore, individual psychosocial support should form a part of the tobacco control ‘package’ to reduce smoking during pregnancy, in conjunction with population-based measures, which have also been shown to have a significant impact on birth outcomes (Adams 2012; Cox 2013) and reducing smoking in disadvantaged populations (Thomas 2008).
The pooled results were not significantly different from zero in eight studies, which were developed predominantly or specifically for ethnic and aboriginal minority women, including African-American women (Gielen 1997; Manfredi 1999; El-Mohandes 2011; Ondersma 2012), African American and Hispanic women (Lillington 1995), Hispanic women (Malchodi 2003), Alaskan Native Women (Patten 2009) and Australian Aboriginal and Torres Strait Islander women (Eades 2012). This is despite primary authors in several studies reporting subgroup analysis of higher quitting rates among African-American and Hispanic women than other women (Petersen 1992; Windsor 1993; Pbert 2004; Parker 2007). These studies tended to involve women more in the development of the intervention and all used several recommended strategies to tailor the intervention (American Legacy Foundation 2012) for initiatives that aim to address the disparities in tobacco use; including hiring culturally competent staff, conducting formative research to identify community needs, piloting and field-testing programs, ‘cultural tailoring’ of smoking cessation resources, and collaborating with key stakeholders and community organisations. Three studies adapted ‘SCRIPT’ materials in the US (see Windsor 2011), which include: 'asking' about smoking status; 'advising' women to quit; 'assisting' women to quit by providing advice on skills and materials such as video's and self-help materials; and arranging for follow-up by referral at future appointments. Two studies developed audiovisual resources for African American (Ondersma 2012) and Alaskan Indian (Patten 2009) women, and these resources received positive feedback. Despite interventions being reported as feasible and acceptable to communities, there were challenges with implementation and few demonstrated an effect size estimate that was significantly different from zero. Further suggestions included trying to recruit from different settings and including elders to improve recruitment, and recognising the importance of broader social interventions for potentially reaching a larger proportion of pregnant women (Patten 2009). Other reviews of interventions in non-pregnant aboriginal peoples have demonstrated interventions can be effective (Carson 2012), and suggest mobile phone technology may be a feasible intervention strategy (Johnston 2013). Only one study included women using smokeless tobacco products, and identified conflicting beliefs about the effect of these products during pregnancy and the primary change recommended by participants in the study was to provide “more objective” information on the risks of Iqmik (smokeless tobacco) use for the infant (Patten 2009).
Most interventions have been developed in high-income countries and there is very limited information about the effectiveness of psychosocial interventions for individual women in low- to middle-income countries (Murthy 2010). The restrictions on tobacco marketing in high-income countries may result in an increase in tobacco marketing companies in low- and middle-income countries. Smoking has the potential to undermine health improvements in low- and middle-income countries and a range of interventions are needed to manage the emerging epidemic (Lopez 1994; Abdullah 2004). However, given the modest effect size estimate of individual interventions, population-based tobacco control strategies are an urgent priority, as there is now a brief 'window of opportunity' to prevent the increase of smoking among women in many low-income countries (Chomba 2010).
Translation of evidence into practice
The first trials of anti-smoking interventions during pregnancy were published more than 30 years ago (Baric 1976; Donovan 1977). The first trial to demonstrate the reversibility of the birthweight reduction associated with smoking by an intensive intervention during pregnancy was published in 1984 (Sexton 1984). Since then, attempts at widespread implementation of psychosocial interventions to support women to stop smoking in pregnancy have demonstrated many of the challenges of translating ‘evidence into practice’, particularly non-pharmacological evidence (Windsor 1998; Windsor 2000b; Lowe 2002; Moore 2002; NICS 2003; McLeod 2004; Herbert 2005; McDermott 2006; Abatemarco 2007; Manfredi 2011).
Studies in this review can be conveniently categorised within a framework for translation of research into practice (Nutbeam 2006), which suggests progression through several stages from; problem definition (descriptive studies) and formative research for intervention design; intervention efficacy research; to implementation in routine/normal settings (effectiveness research); dissemination across several settings; and institutionalisation (as interventions are provided as part of routine care). Many studies in this review clearly defined the problem and conducted formative research for intervention development (Katz 2008; Gilligan 2009), particularly interventions developed for vulnerable women, including young women (Albrecht 1998; Albrecht 2006). The modest but significant efficacy of psychosocial interventions provided by researchers has been well demonstrated by studies in this review, including counselling interventions.
The transfer of an intervention from one setting to another may reduce its effectiveness if elements are changed or aspects of the materials are culturally inappropriate. An example in these trials was the performance of the Windsor self-help manual. This was developed and shown to be effective in Birmingham, Alabama (Windsor 1985; Windsor 1993). However, when it was implemented into routine care (Windsor 2011), used in Baltimore with peer counsellors who received minimal training instead of trained health educators (Gielen 1997), adapted for Alaskan Native women (Patten 2009) and transferred to other countries (Lowe 1998a; Lowe 1998b), the effectiveness was much lower. An analysis of health promotion trials has concluded that where the providers are also the researchers (more likely in single centre studies than multicentre studies), they appear to be better providers for influencing behavioural outcomes and about the same as other providers for other outcome domains (Oliver 2008a). The larger, multicentre trials may therefore be a more accurate representation of implementing policy than smaller, single centre trials. In this review, interventions provided by usual care providers were as effective as interventions provided by researchers, including counselling interventions. However, there was substantial heterogeneity in sensitivity analyses of trials provided by usual care providers in this review, which supports the views that there are many variables to consider when implementing interventions in routine settings (Hoddinott 2010).
Despite evidence of efficacy and effectiveness, dissemination trials of counselling interventions into pregnancy care settings suggest challenges to translating this efficacy research into routine practice and policy. Data from the five dissemination trials that targeted the intervention at the organisational level, demonstrated significant effects in terms of increased implementation of interventions in routine practice, although challenges were reported and this did not translate into a significant reduction in rates of smoking among women in the intervention arms of these studies. One study that provided clinics with resources and referral options reported an increase in women’s recall of receiving interventions (Manfredi 1999). A significantly higher program implementation rate was reported when using an intervention based on Rogers' 'Diffusion of Innovation' theory (43% compared with only 9% implementation in the control group after one year), but there were no data on the impact on smoking outcomes (Lowe 2002). An increased uptake of the intervention by staff was demonstrated using ‘active’ dissemination compared to a simple mail-out of information (Cooke 2001), but not at levels sufficient to have a significant impact on smoking outcomes in women (Campbell 2006), which was similar to other dissemination trials reporting smoking outcomes (Pbert 2004; Windsor 2011). Another non-randomised study compared the use of the RE-AIM dissemination model to increase the reach, efficacy, adoption, implementation, maintenance of interventions (Lando 2001) and concluded that multi-faceted approaches using strategies from each intervention were most likely to improve implementation.
There are a number of possible explanations for the limited effect in dissemination trials. Firstly, many of the studies that recruited individual women did not provide information on the number of women who were eligible for inclusion or were approached to take part in trials. The 'participation rate' would have provided useful information about the general ‘acceptability’ of the intervention, as well as the degree of ‘selection bias’ in the study population (Sedgwick 2013). Among those studies that did report the proportion approached and recruited from the total ‘eligible’ population, low participation rates were often reported. Therefore, some of the evidence in this review is from selective samples of the population of women who smoke during pregnancy. Women participating in studies (Mullen 1997) were more likely to be in contemplative and preparation stages of change, be ‘recent quitters’ and have a lower gestational age, compared to women not participating studies (Ruggiero 2003). The majority of women categorised as ‘Black’, ‘White’ and ‘Native American’ did enrol in the study, while women categorised as ‘Hispanic’ were less likely (51.6%) to enrol and the majority of Asian women did not enrol (Ruggiero 2003). Dissemination trials and ‘cluster trials’ that randomise clinics or providers are therefore likely to provide a more accurate estimate of the likely effect in a non-selective population of pregnant women.
Secondly, the implementation of interventions under conditions less stringent than an individually-randomised controlled trial may be reduced, which may limit exposure of the intervention group to the intervention, or components of the interventions (Walsh 2000). Several trials implemented in routine care settings by midwives (Moore 2002; DeVries 2006), doctors (Valbo 1994; Walsh 1997), and routine clinic staff (Kendrick 1995) reported difficulties with implementation. Some of the issues included: variable perceptions of smoking cessation as part of the providers' role (DeVries 2006), stating they were too busy and did not have enough time to complete the intervention (Dunkley 1997; Haines 1998; Hajek 2001; Valanis 2001b; Leviton 2003), difficulty recruiting providers to the study (Lawrence 2003), providers reporting pessimism about the efficacy of the intervention (Moore 2002), and lack of acceptability of resources (Lowe 1998a; McBride 1999). Several studies reported positive 'facilitators or enabling factors' associated with implementation. Proposed criteria for interventions to be implemented into routine maternity care include: having program materials readily available; feasible provider time commitments; clear training requirements; minimal organisational and administrative barriers (Strand 2003); and program components that are acceptable to providers and women (Haynes 1998; Cabana 1999; Grol 1999; Walsh 2000; Cooke 2001a). Written resources, a written protocol to identify staff responsibilities, and reimbursement have also been suggested as other strategies to improve implementation (Hartmann 2007). A significant increase in both intervention delivery and smoking outcomes was seen in a cluster trial that supported staff with training based on national guidelines, a clinic management system, and establishment of program boards (Pbert 2004). Suggestions to overcome the barriers in a busy clinic setting included increasing the use of referral services and technology to reduce demand on clinicians’ time (Moore 2002). Subsequently, use of referral services such as ‘quitline’ (Williams 2010) and technology-driven interventions have gained popularity in the past five years (Tsoh 2010; Naughton 2012; Ondersma 2012). In the United Kingdom (UK), most services reported use of ‘quitline’ referral services (Williams 2010). One excluded (non-randomised) study in South Australia (Bowden 2010), describes positive experiences and perceptions of staff in implementing a 'Smoke-free Pregnancy' Project involving brief '5A's' intervention and referrals to ‘quitline’. While use of materials such as self-help materials and technological aids did not appear to significantly increase rates of smoking abstinence in this review, they may help to increase the feasibility and reduce the costs of delivering interventions.
A third possible explanation for the limited effect seen in implementation is that trials that involve broader implementation across the system and provision by usual care providers (effectiveness studies), may result in greater exposure of the comparison group to the intervention. While the difference was not significantly different, the pooled effect size was lower among trials that were assessed as having a high risk of contamination in this review. One study illustrated this effect by including a ‘historical control’ group, in which only 4% stopped smoking, compared to 10% who stopped in the randomised ‘concurrent control’ and 12% in the intervention group who stopped (Windsor 2011).
Institutionalisation, where interventions are part of routine care, is the final stage of the evidence-practice translation process. Australia, Canada, the UK and the United States (US) have developed guidelines recommending all pregnant women receive interventions to promote smoking cessation in pregnancy (Aveyard 2007; Fiore 2008). However, studies of clinicians practice in Canada, the US and Argentina suggest that while the majority (50% to 100%) ‘ask’ about smoking status, rates of assistance with effective strategies to support women to stop smoking are very low (11.5% to below 50%) (Floyd 2001; Hartmann 2007; Tong 2008; Mejia 2010; Okoli 2010). Strategies to address the deficiencies identified in these surveys are reported (Chapin 2004) and several studies in this review have trialled strategies to adapt these guidelines and improve implementation into routine settings (Tsoh 2010; Ondersma 2012). A recent survey suggests attitudes may be shifting in the UK about the provision of advice and support, but not the efficacy of the interventions (Beenstock 2012). A recent survey of women giving birth in Australia suggests there has been a significant increase in the provision of smoking advice and support in routine pregnancy care from 2000 to 2008, though half of smokers still did not receive the full complement of advice and support according to state guidelines, and there was marked variability according to where and from whom women received antenatal care (Perlen 2013).
Strategies to increase disclosure of smoking status
Barriers to implementation have been identified at each step of service provision in relation to support for smoking cessation in pregnancy. This includes detection of women who smoke so they can then be offered a supportive intervention (Tappin 2010). As previously noted, self-reported disclosure of smoking status can be variable. Disclosure is influenced by several factors, including the stigma and guilt associated with smoking in pregnancy, the relationship between the care provider and the way the woman is asked about smoking. In general, it appears that less direct questioning increases disclosure, for example, changing the question format from ‘yes’ or ‘no’ to a series of multiple choice questions and asking women to best describe their smoking status (Mullen 1991). There is some evidence from the literature around broader substance use in pregnancy, that asking about substance use of family members (e.g. secondhand smoke exposure) first (Chasnoff 2005; Chasnoff 2007), and leaving sensitive probing personal questions until later in the interview, when a rapport has been established. The rationale is that this provides an opportunity for the woman to gauge the response of the healthcare provider and feel more confident disclosing her smoking status. In the UK, ‘opt out’ carbon monoxide screening has been proposed to increase disclosure (Tappin 2010; Bauld 2012). Biochemical validation of smoking status is an understandable pre-requisite prior to receipt of contingent incentives, to provide feedback on cotinine levels as a motivational aid; or in the context of a smoking trial. However, the benefits and rationale for not accepting women’s disclosure outside these contexts is unclear and was not well received by women in this review (Thornton 1997). Furthermore, there are questions about the accuracy of carbon monoxide monitoring among women with high secondhand smoke exposure (McLaren 2010), and whether there are any adverse effects from routine screening, such as increased domestic violence or effects on mental health.
Adverse effects of interventions
While psychosocial interventions do not pose the same risks to fetal health as pharmacological agents in pregnancy, there are concerns about the potential unintended consequences of these interventions that aim to encourage pregnant women to stop smoking (Burgess 2009). The potential adverse effects identified in this review include: increased smoking; unhelpful peer or partner support; stigmatisation; and nicotine withdrawal.
Despite the number of studies reporting smoking reduction, only three studies reported rates of women who increased smoking by intervention group, and these showed mixed results (Hjalmarson 1991; Haug 1994; Tappin 2005). It would be helpful for studies to measure any increased smoking, particularly in light of recent qualitative evidence that suggests anti-smoking advice may increase resistance to smoking messages for some women (Bond 2012; Flemming 2013).
There has been an increasing focus on the partners and peers of pregnant women, with the additional aim of facilitating cessation by the women themselves (Stanton 2004; Gage 2007). In some cases this reflects cultural and demographic patterns of smoking, where smoking rates are still highest amongst men (Loke 2005; Kazemi 2012); in others, interest in environmental barriers that hinder smoking cessation has led to an understanding of the influence of a woman’s social networks on smoking behaviour (McBride 2004). Studies in this review suggest that there are both positive and negative aspects to partner and peer assistance with supporting women to stop smoking in pregnancy (McBride 2004; Hennrikus 2010). This legitimises concerns about the potential adverse effects on relationships and women’s position (Greaves 2007a). Therefore, these risks should be taken into consideration when developing interventions involving partners or peers, particularly in subpopulations or regions where protection for women’s rights are less than optimal. Pro-active measures to identify women at risk and ensure their safety should be implemented as part of interventions involving peer or partner support (Greaves 2007b).
No studies measured the impact of interventions on stigmatisation of women. However, studies of psychological impact do not suggest there are any negative effects, and individual psychological support may be beneficial (Stotts 2004; Bullock 2009; Cinciripini 2010). Nevertheless, public health professionals must remain ever vigilant when implementing population-based measures, as policies can disrupt highly complex systems and unintended consequences of tobacco policy may differentially impact on vulnerable population groups (Healton 2009). Stigmatisation research suggests that such policies may have unanticipated outcomes for vulnerable mothers, including decreased mental health; increased use of alcohol or cigarettes; avoidance or delay in seeking medical care; and poorer treatment by health professionals (Moore 2009). This stigmatisation may be compounded for some population groups, such as racial minority groups (Bond 2012; Flemming 2013).
Few studies reported the effect of nicotine withdrawal, which is a gap given that these withdrawal effects may be more acute during pregnancy (Ussher 2012a; Ussher 2012b).