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Keywords:

  • Maternal age;
  • postpartum;
  • postponement of childbirth;
  • pregnancy;
  • psychological distress

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

Please cite this paper as: Aasheim V, Waldenström U, Hjelmstedt A, Rasmussen S, Pettersson H, Schytt E. Associations between advanced maternal age and psychological distress in primiparous women, from early pregnancy to 18 months postpartum. BJOG 2012;119:1108–1116.

Objective  To investigate if advanced maternal age at first birth increases the risk of psychological distress during pregnancy at 17 and 30 weeks of gestation and at 6 and 18 months after birth.

Design  National cohort study.

Setting  Norway.

Sample  A total of 19 291 nulliparous women recruited between 1999 and 2008 from hospitals and maternity units.

Methods  Questionnaire data were obtained from the longitudinal Norwegian Mother and Child Cohort Study, and register data from the national Medical Birth Register. Advanced maternal age was defined as ≥32 years and a reference group of women aged 25–31 years was used for comparisons. The distribution of psychological distress from 20 to ≥40 years was investigated, and the prevalence of psychological distress at the four time-points was estimated. Logistic regression analyses based on generalised estimation equations were used to investigate associations between advanced maternal age and psychological distress.

Main outcome measures  Psychological distress measured by SCL-5.

Results  Women of advanced age had slightly higher scores of psychological distress over the period than the reference group, also after controlling for obstetric and infant variables. The youngest women had the highest scores. A history of depression increased the risk of distress in all women. With no history of depression, women of advanced age were not at higher risk. Changes over time were similar between groups and lowest at 6 months.

Conclusion  Women of 32 years and beyond had slightly increased risk of psychological distress during pregnancy and the first 18 months of motherhood compared with women aged 25–31 years.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

Maternal age at first childbirth has increased dramatically during the last few decades in most high-income countries.1,2 In Norway, the average age of women having their first baby was 23 years in 1975, and 28 years in 2011.3 The postponement of childbearing has been high on the medical research agenda for many years because of the increased risk of infertility4 and medical complications such as caesarean section,5 intrauterine growth restriction and low birthweight,6 perinatal morbidity6,7 and perinatal mortality.6,8 In contrast to the considerable attention paid to the physical consequences of delaying childbirth, relatively little attention has been paid to exploring the psychological wellbeing of older first-time mothers.9

Findings presented in studies of emotional wellbeing in older mothers are inconclusive.10 In some studies, women of advanced age were not at an increased risk of depressive symptoms either during pregnancy11–13 or during the first year of motherhood12,14 compared with younger women. In contrast, other studies found a higher prevalence of worries during pregnancy11 and depression postnatally15–17 in older women. An Australian study reported that first-time mothers older than 35 years were more depressed at 1 month but not at 4 months after the birth, compared with women aged 24–34 years.18 Another study reported that the risk of psychotic illness immediately following the first birth increased more than two-fold in women over 35 years of age compared with younger women.19 In addition, some medical complications that are more prevalent in older primiparous women, such as emergency caesarean delivery and preterm birth, increase the risk of depression and anxiety.20,21 Although some of these findings seem to indicate that higher maternal age may increase the risk of psychological distress, it has also been suggested that postponing childbirth may be beneficial from a psychological point of view because of the woman’s more stable socioeconomic situation22 and increased personal maturity.7

The principal aim of the present study was to investigate if advanced maternal age at first birth increases the risk of psychological distress during pregnancy in gestational weeks 17 and 30, and at 6 and 18 months after the birth. By investigating the distribution of psychological distress over the age span, from 20 to ≥40 years, at all the four time-points, information was also obtained about younger women.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

Data were drawn from the longitudinal population-based Norwegian Mother and Child Cohort Study (MoBa), carried out by the Norwegian Institute of Public Health. The MoBa study investigates sociodemographic, physical, genetic and mental health exposure variables and outcomes in mothers and children. The method has been described in detail in previous publications.23,24 Norwegian-speaking women were recruited in the period between 1999 and 2008 from all Norwegian hospitals and maternity units with more than 100 births annually. A postal invitation was sent out after the women had registered for a routine ultrasound examination at approximately 17 weeks of gestation. The invitation included an informed consent form and the first of six questionnaires. The current study is based on version 4 of the quality assured data files. In the present study, data from four of the questionnaires were used: gestational weeks 17 (Q1) and 30 (Q2), and 6 months (Q3) and 18 months (Q4) after the birth. A letter of reminder was sent out after 2–3 weeks to women with unreturned questionnaires. The first questionnaire obtained information about sociodemographic background (education, civil status, native language, mothers’ income (NKR), unemployment and smoking), reproductive background (previous pregnancies), weight and height and history of depression (the woman was asked to tick a box if she had suffered from depression before the current pregnancy). In addition, the questionnaire included an instrument of psychological distress (see description below). The same questions regarding psychological distress were included in all the questionnaires. Data on maternal age, parity, mode of delivery, infant outcome (neonatal transfer, prematurity), smoking, civil status and in vitro fertilisation treatment were retrieved from the Norwegian Medical Birth Register, which covers all births and includes information from the standardised medical records used by all antenatal clinics and delivery units in Norway.25

Participants

For the present study, only first-time mothers who had responded to all four questionnaires, including the questions about psychological distress, and who had complete data from the Medical Birth Register on parity and age were included. We also excluded women recruited after year 2006 because they, at the time of conducting the present study, had not yet filled in the follow-up questionnaire at 18 months after birth. Teenagers were excluded because they constituted a selected group and were beyond the scope of this paper. First-time mother was defined as a woman who had not given birth previously; neither to a live infant nor to a stillborn after 21 weeks of pregnancy.26

The flow-chart (Figure 1) shows the initial MoBa sample and the final study sample, which was 19 291 women, after exclusions of the drop-outs. The 11 605 drop-outs (37.6%) included women who had responded to Q1 but not to one or more of the subsequent questionnaires (Q2–Q4), and 684 women who filled in fewer than three items on the scale measuring psychological distress (see below). To determine the representativeness of the study sample it was compared with all women aged ≥20 years who gave birth to their first child in Norway in 2003. Psychological distress was investigated also in the drop-outs who had responded to the questionnaire in week 17 of gestation but not thereafter.

image

Figure 1.  Recruitment, sample and dropouts. Q, Questionnaire; gwks, gestational weeks; pp, post partum. Drop-outs: non-responders to Q + responders with incomplete SCL-5 (less than 3 of the 5 items).

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Outcome variable

Psychological distress was measured using a shortened version of the widely used Symptom Check List (SCL-25),27 i.e. the Hopkins Symptom Checklist (SCL-5), which is a five-item self-report scale including two dimensions: depressiveness (three items) and anxiousness (two items). The responder was asked if she had been bothered by any of the following during the last 2 weeks: feeling fearful, nervousness or shakiness inside, feeling hopeless about the future, feeling blue, and worrying too much about things. Each item is scored on a four-point scale (1 = not bothered, 2 = a little bit bothered, 3 = quite bothered and 4 = very bothered) with a total score ranging from 5 to 20. A mean value is then calculated. The SCL-5 has shown high correlation (r = 0.91) with the original global SCL-25, which is a valid measure of psychological distress.28 A Cronbach’s Alpha between 0.85 and 0.8729,30 has been reported. A cut-off score of ≥2.0 for psychological distress is recommended in a general population,30 but the scale has not been validated in the context of childbearing. This cut-off would have defined a smaller proportion of our sample as suffering from psychological distress than has been reported in studies of depressive symptoms in relation to childbirth, as measured by the Edinburgh Postnatal Depression Scale (EPDS).15,31–36 Although the SCL-5 and EPDS are different tools, we chose to take these findings into consideration, setting a lower SCL-5 cut-off at ≥1.75 to capture a similar proportion of psychologically distressed women as in the EPDS-based surveys of depression. This decision was also justified by the fact that it was not our aim to study the prevalence of psychological distress as such, but rather possible differences related to maternal age, including the mean value for each age group, as well as differences over time. In women for whom a maximum of two items on the scale were missing, imputation was used on the remaining items.

Explanatory variable

Age was defined as maternal age at the time of giving birth. There is no consensus as what should be defined as a young and old first-time mother, and maternal age is often presented in intervals of 5 years.1,6,37 The young may, for example, be defined as teenagers38 or as mothers <25 years old11,18 and the ‘old’ as those over 25 years,39 30 years40 or 35 years5 of age. These definitions seem mainly to be guided by the size of the study sample. We decided to base the decision about age cut-off on data from the entire Norwegian birth cohort from 2003, retrieved from the Medical Birth Register. Using the breakpoints for the lower (24/25 years) and upper (31/32 years) quartiles, young age was defined 20–24 years and advanced age as ≥32 years. The comparison group was defined as women aged 25–31 years.

Confounders

To avoid adjusting for the natural process of ageing, potential confounders were restricted to the following socioeconomic factors: education, single status, native language other than Norwegian, mother’s income (NKR), unemployment and smoking. To explain differences between women of advanced age and the reference group, we entered also operative delivery (caesarean section, instrumental delivery) and infant outcome (neonatal transfer, prematurity) into the models.

Statistical analyses

Differences in proportions and means between the age groups and between a subsample giving birth in 2003 and all Norwegian primiparous women in 2003 (women in the sample excluded), were calculated by chi-square test and Student’s t test, respectively.

The associations between age and psychological distress as well as potential confounders and explanatory factors were first tested in bivariate analyses. Multivariable logistic regression models based on the methods of generalised estimation equations were then used to adjust for independent factors divided into blocks, which were entered in the following order: (1) time point, (2) sociodemographic factors, (3) operative delivery and (4) infant outcome. Generalised estimation equations would accurately deal with the problem that repeated observations for the same individual are often correlated. If the intra-cluster correlation is ignored, this may lead to imprecise variation estimates from the regression models, leading to incorrect statistical and biological conclusions. Such correlation violates the assumption of independence necessary for more traditional repeated-measures analysis and leads to bias in regression parameters.41 We used a binary logistic model and the variance–covariance for all models was assumed to be block diagonal but unstructured within a block defined by subjects. Finally, to study whether the effect of age differed across any of the independent factors, we tested the interactions between age and each factor, one at a time, after adjusting for all other factors. All tests were two-sided. The results are presented as crude and adjusted odds ratios (OR) with their 95% Wald confidence intervals (CI).42 Imputations on the SCL scale were made if a maximum of two items on the scale were missing. We used a single-imputation method, Missing Values Analysis—Expectation Maximisation algorithm43 as suggested by researchers who validated the scale in Norway (K. Tambs, pers. comm.) and previously used on the SCL-5 scale in the MoBa. As predictors for imputations, valid data on the remaining items on the scale were used. We replaced missing values on the scale in 1.42%, 1.44%, 1.02% and 0.84% of cases in the Q1–Q4, respectively. The analyses were conducted using SPSS, version 20 (SPSS, Inc., Chicago, IL, USA). The study was approved by the appropriate Regional Committees for Ethics in Medical Research and the Norwegian data Inspectorate (S–97 045).

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

When comparing only those women who gave birth in year 2003 in our sample with the total Norwegian birth cohort of primiparas during the same year we found that the following characteristics were under-represented in our sample: age 20–24 years, smokers, single status, caesarean delivery, premature birth and infant transfer to neonatal intensive care unit (Table 1).

Table 1.   Background characteristics of the age groups, the total study sample, a sub-sample giving birth in 2003, and all primiparous women aged ≥20 years in Norway in 2003
 Age 20–24 n = 3106 (%)Age 25–31 n = 11 801 (%)Age ≥ 32 n = 4384 (%)Total study sample n = 19 291 (%)Sub-sample giving birth in 2003 n = 3693 (%)Primiparous women in the Norwegian birth cohort of 2003 n = 22 272 (%)P value (sub-sample vs national birth cohort 2003)
  1. BMI, body mass index; IVF, in vitro fertilisation; NKR, Norwegian krone.

  2. *Data from the Norwegian Medical Birth Register.

Demographic and social factors
Age (years)*
 20–24   16.117.124.7<0.0001
 25–29   44.845.840.7
 30–34   30.529.526.5
 35–39   7.877.2
 ≥40   0.90.60.9
Pregravida BMI, mean (kg/m2)24.724.625.324.8   
Smoking*18.37.99.310.512.816.8<0.0001
Single status*82.35.13.63.47.6<0.0001
Native language other than Norwegian3.44.7754.4  
Unemployed51.92.12.5   
Income (NKR)
 <200 00031.312.87.413.6   
 200 000–399 99960.463.853.457.3   
 ≥400 0008.323.439.223.2   
Psychological and reproductive health
Depression before pregnancy7.35.586.3   
IVF present pregnancy*0.42.58.13.53.43.80.13
Labour*
Mode of delivery
 Unassisted vaginal delivery75.670.16068.76966.4<0.0001
 Instrumental vaginal delivery12.115.818.215.815.615.2
 Elective caesarean section2.235.73.53.34.7
 Emergency caesarean section9.21014.610.910.811.5
 Unspecified caesarean section1.11.51.81.51.32.2
Prematurity5.86.27.16.36.58.3<0.0001
Neonatal transfer10.310.411.89.910.211.90.001

When comparing the oldest age group in our sample with the reference group we found that the following characteristics were more common: high mean pregravid BMI (P < 0.001), smoking (P < 0.001), single status (P < 0.001), native language other than Norwegian (P < 0.001), high income (P < 0.001) and depression before pregnancy (P < 0.001). The oldest women also had higher rates of IVF (P < 0.001), caesarean delivery (P < 0.001) and premature birth (P < 0.05), and their babies were more often transferred to neonatal intensive care (P < 0.05). The following characteristics were more prevalent in the youngest women compared with the reference group regarding: smoking (P < 0.001), single status (P < 0.001), unemployment (P < 0.001), low income (P < 0.001), depression before pregnancy (P = 0.001), and Norwegian speaking background (P = 0.01). They also had higher rates of spontaneous vaginal birth (P < 0.001).

The prevalence of psychological distress in the total sample was 9.7% in week 17 of gestation, 9.9% in week 30 of gestation, 7.1% at 6 months and 11.0% at 18 months after the birth. Figure 2 presents psychological distress by maternal age, and shows that the youngest women had the highest scores on all occasions and women in the reference group had the lowest. Women of 32 years and beyond had slightly higher rates than the reference group. A figure based on the mean SCL-5 values resulted in an almost identical pattern (not shown). Figure 2 also reveals that the women who withdrew from the study after having filled in the first questionnaire constituted a selected group with higher rates of psychological distress. The proportion of these drop-outs was 14.1% in the youngest group, 10.1% in the reference group and 10.3% in the oldest group. The proportions of drop-outs with psychological distress were 26.7%, 14.5% and 13.6% in the respective group.

image

Figure 2.  Psychological distress (SCL-5 > 1.75) in relation to maternal age at 17 and 30 weeks of gestation and at 6 and 18 months after birth in the study sample of 19 291 women expecting their first baby, and in 10 922 drop-outs after week 17 of gestation (with baseline data on SCL-5).

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Figure 3 shows psychological distress by time of measurement. On all occasions the prevalence was slightly higher in women of advanced age than in the reference group, and almost twice as high in the youngest group (see Table 2 for crude OR and 95% CI). Across the time period the pattern was similar in all groups, suggesting that the effect of time was similar regardless of age. Compared with early pregnancy, the prevalence in the total sample was similar in late pregnancy (OR 1.0; 95% CI 1.0–1.1), had dropped by 6 months postpartum (OR 0.7; 95% CI 0.7–0.8), and increased at 18 months (OR 1.2; 95% CI 1.1–1.2).

image

Figure 3.  Psychological distress (SCL-5 ≥ 1.75) in primiparous women aged 20–24, 25–31 and ≥32, in weeks 17 and 30 of gestation and 6 and 18 months after the birth (n = 19 291).

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Table 2.   Prevalence of psychological distress (SCL-5 ≥1.75) in gestational week 17, and OR for psychological distress longitudinally during pregnancy and 18 months after the birth (gestational weeks 17 and 30, and 6 and 18 months after the birth) in primiparous women aged 20–24, 25–31 and ≥32 years (n = 19 291)
AgenPsychological distress in gestational week 17 (%)Crude OR95% CIAdj OR* (95% CI)Adj OR** (95% CI)Adj OR*** (95% CI)Adj OR**** (95% CI)Adj OR***** (95% CI)Adj OR***** (95% CI)
  1. Crude and adjusted odds ratios (OR) and 95% Confidence Interval (CI).

  2. *Adjusted for time point.

  3. **Adjusted for * and Sociodemographic variables: education, single status, native language, mother’s income (NKR), unemployment and smoking.

  4. ***Adjusted for * and ** and Operative delivery: emergency caesarean section, instrumental vaginal delivery.

  5. ****Adjusted for *, ** and *** and Infant outcome: neonatal transfer, prematurity.

  6. *****Adjusted for *, **, *** and ****.

20–24310615.31.81(1.66–1.97)1.80 (1.65–1.95)1.25 (1.14–1.37)1.25 (1.14–1.38)1.26 (1.14–1.39)  
25–3111 8018.51 1111  
≥3243849.21.17(1.07–1.27)1.16 (1.06–1.26)1.14 (1.04–1.25)1.14 (1.04–1.24)1.14 (1.04–1.25)  
Interaction effect of age and unemployment
Unemployed
 20–2415628.8      1.98 (1.49–2.63) 
 25–3123017.4      1.94 (1.49–2.52) 
 ≥329112.1      1.15 (0.74–1.81) 
Employed
 20–24295014.6      1.27 (1.15–1.41) 
 25–3111 5718.3      1 
 ≥3242919.1      1.16 (1.06–1.28) 
Interaction effect of age and a history of depression
History of depression
 20–249742.7       5.73 (4.60–7.14)
 25–3121633.3       5.75 (5.01–6.59)
 ≥3212435.5       7.00 (5.84–8.38)
No history of depression
 20–24287913.2       1.34 (1.21–1.49)
 25–3111 1537.0       1
 ≥3240356.9       1.03 (0.93–8.38)

Table 2 shows the crude and adjusted odds ratios for psychological distress in young and older women, and in the reference group (25–31 years), one model for each block of variables. As previously shown in Figure 3, women of advanced age had slightly increased odds for psychological distress, independent of time, and the odds ratios remained almost unchanged when adjusting for sociodemographic background. To further understand what lies behind the increased risk of distress, we entered also operative delivery (emergency caesarean section, instrumental vaginal delivery) and infant outcome (neonatal transfer, prematurity) into the model, but the figures remained stable. The higher risk in the youngest women, also independent of time, decreased from 1.81 to 1.25 when entering sociodemographic variables into the model, but then remained unchanged when adding operative delivery and infant outcome.

Interactions between age and all factors described in Table 2 were then tested. Unemployment interacted with age (P = 0.042), and most strongly in the women aged 20–24 and 25–31 years who had a two-fold risk of psychological distress when compared with women who were employed in the reference group. Psychological distress in women of advanced age was less affected by unemployment. Having had one or more episodes of depression before pregnancy also interacted with age (P = 0.008). All women with a history of depression were at higher risk of distress than those without such background, and the highest risk was observed in the oldest women who had a seven-fold odds for psychological distress. Without a previous depression, the oldest were not at a higher risk than the reference group.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

In this national sample the prevalence of psychological distress was slightly higher in older first-time mothers than in a reference group aged 25–31 years, when measured in weeks 17 and 30 of gestation, and at 6 and 18 months after the birth. This finding contrasts with the view that postponing childbirth is beneficial from a psychological point of view, as suggested by some authors.7,22 However, advanced age at first pregnancy only increased psychological distress in women who reported having suffered from depression before pregnancy.

Although the youngest group was not the major focus of our study and teenagers were excluded, the inclusion of women aged 20–24 years in our study contributed to a more comprehensive view of the distribution of psychological distress in primiparous women, and it became obvious that the increase in older women was much less pronounced than in the youngest group. The slightly U-shaped pattern of psychological distress over the age span may be explained by socioeconomic disadvantage, such as unemployment, on the left hand side of the distribution and history of depression on the other side. Other factors may also be important, such as timing of pregnancy. In both the youngest and the oldest groups the timing may not have been optimal. A recent study of 2500 US women44 found that mistiming of the first birth accounted for the curvilinear relationship between age and psychological distress. Deviating from life course expectations and violating social age norms, may result in an identity discrepancy, which as such is associated with mental health problems. Further, older women may have more accumulated trauma and physical health problems.20,21,45 However, we cannot rule out the possibility that anxiety or depression caused some of the older women to postpone their pregnancy, rather than the other way around.

Sociodemographic factors, particularly unemployment, contributed to psychological distress in the young primiparas, a finding also reported by others.31,46 This was not the case in the oldest group suggesting that these women felt more secure about their position in the workforce, probably because of higher education and income.

In all age groups, and regardless of history of depression, psychological distress was least common at 6 months after the birth. This finding is supported by other studies12,34 and has been interpreted as a period when the mother has adapted to the new role as a mother, and in a country like Norway she will still be on parental leave and not yet confronted with the challenge of combining motherhood and work outside home.

Women in the oldest group had been more exposed to events associated with psychological problems, such as caesarean delivery and instrumental vaginal delivery,20 prematurity,21 and infant transfer to neonatal care.20 Adding these factors into the analysis did not change the odds of psychological distress in the oldest women with a history of depression, suggesting that medical complications were of less importance. However, this conclusion does not take into account the women who dropped out of the study and who constituted a selected group with more complications, including caesarean delivery (17.8% versus 15.9%) and preterm birth (8.9% versus 6.3%). The age-related adverse obstetric and neonatal outcomes may therefore still have contributed to our findings. We can only speculate as to whether other age-related factors may have been important, such as fatigue, high blood pressure and diabetes, or psychosocial factors, such as unrealistic expectations and the unpredictability of life as a parent.

A limitation of our study was that psychological distress was not measured by an instrument validated for the study population and our choice of cut-off could be questioned for being too low. However, the cut-off at SCL-5 ≥ 1.75 was set to adapt to the prevalence of depressive symptoms during pregnancy and postpartum in Scandinavian settings, measured by, for example the EPDS,47 and not depression as a clinical diagnosis. Clinically, the measurement of depressive symptoms has been important and screening tools are being introduced in many antenatal clinics to identify women at risk of depression to provide adequate preventive support. A review by Gavin et al.48 reported a prevalence of major perinatal depression of 3–5% whereas minor depression was estimated to be 9–13%, which is similar to our figures.

Our choice of cut-off identified approximately 10% who were psychologically distressed, but the analysis of drop-outs after the first questionnaire suggests that this could be an underestimate of the rate in the total population of nulliparous women, particularly in the youngest and oldest groups. In addition, women with sociodemographic and some obstetric risk factors for depression were under-represented in our sample compared with the national birth cohort, and these risk factors are more prevalent in young31,46 and older20,21 women.

Another limitation was that information about ‘history of depression’ was based on self-reports on a single-item question. Still, our findings show that a single question about history of depression identifies women who are at increased risk of being distressed during pregnancy and postpartum.

Clinical implications

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

It is well established that caregivers need to pay extra attention to the needs of pregnant teenagers.48,49 With the growing tendency to postpone childbirth in high-income countries the definition of a young and old first-time mother has changed and new groups of women are now exposed to psychological distress during pregnancy and early parenthood. Caregivers should be extra alert to women with a previous history of depression, regardless of age, and also to first-time mothers in their twenties without a job, who may need extra attention and support.

Contribution to authorship

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

VAA analysed the data, contributed to the interpretation of findings and wrote the first draft of the manuscript. UW was the principal investigator and contributed with the idea, the interpretation of the results and with writing the manuscript. AH contributed to interpretation of results and by commenting on the manuscript. SR contributed in the analyses, and commented on the manuscript. HP contributed to the data analyses and writing of the manuscript. ES contributed to the planning of the study, to the data analyses, the interpretation of the results and the writing of the manuscript. All authors have approved the final version of the manuscript.

Details of ethics approval

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

The study was approved by the appropriate Regional Committees for Ethics in Medical Research and the Norwegian data Inspectorate (S–97 045).

Funding

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

The Norwegian Mother and Child Cohort Study is supported by the Norwegian Ministry of Health and the Ministry of Education and Research, NIH/NIEHS (contract no NO-ES-75 558), NIH/NINDS (grant no.1 UO1 NS 047 537-01), and the Norwegian Research Council/FUGE (grant no. 151 918/S10). This study was funded by the Swedish Research Council, Karolinska Institutet, Stockholm, Sweden and by Bergen University College, Norway

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References

The permission to use questionnaires from MoBa participants is acknowledged. We are grateful to all the participating families in Norway who take part in this on-going cohort study.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Clinical implications
  8. Disclosure of interests
  9. Contribution to authorship
  10. Details of ethics approval
  11. Funding
  12. Acknowledgements
  13. References