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Keywords:

  • labor pain;
  • longitudinal cohort study;
  • overall birth experience;
  • posttraumatic stress symptoms after childbirth

Abstract

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References

Background

The aim of this prospective study was to investigate the role of labor pain and overall birth experience in the development of posttraumatic stress symptoms in a comprehensive framework.

Methods

The study sample (N = 1893) comprised women with a vaginal delivery and was drawn from the Akershus Birth Cohort, which targeted all women scheduled to give birth at Akershus University Hospital in Norway. Questionnaires were given at three different stages: from pregnancy weeks 17 to 32, from the maternity ward, and from 8 weeks postpartum. Data were also obtained from the hospital's birth record. Using structural equation modeling, a prospective mediation model was tested.

Results

Posttraumatic stress symptoms were significantly related to both labor pain (r = 0.23) and overall birth experience (r = 0.39). A substantial portion (33%) of the effect of labor pain on posttraumatic stress symptoms was mediated by the overall birth experience.

Conclusions

Although the results of this study showed that both labor pain and overall birth experience played a role in the development of posttraumatic stress symptoms after childbirth, overall birth experience appeared to be the central factor. The women's birth experience was not only related to posttraumatic stress symptoms directly but also mediated a substantial portion of the effect of labor pain on posttraumatic stress symptoms. Future work should address which areas of birth experience confer protective effects on women to improve clinical care.

Up to one-third of all women view their labor and delivery as traumatic [1, 2]. An estimated 2–6 percent of women experience the full constellation of symptoms of posttraumatic stress disorder (PTSD) relating to childbirth and qualify for a clinical PTSD diagnosis [3]. Prevalence has typically been measured within the first 6 months postpartum, but evidence suggesting the potential longevity of posttraumatic responses can be seen in some women [4]. It has been shown that higher levels of posttraumatic symptoms are associated with an increased likelihood of not having further children or of delaying a subsequent pregnancy [5, 6]. In addition, it has been suggested that a new pregnancy has the potential to reactivate the posttraumatic symptoms [3].

The Diagnostic and Statistical Manual for Mental Disorders (DSM-IV) categorizes symptoms of PTSD in three symptom clusters: re-experiencing symptoms (e.g., nightmares about the delivery, flashbacks of the event), avoidance symptoms (e.g., avoiding getting pregnant again, amnesia around the event), and increased arousal symptoms (e.g., irritability, concentration problems) [7, 8].

As traumatic stressors are rarely predictable, most studies investigating risk factors of PTSD are limited by the use of retrospective designs, studying people only after the traumatic event [9]. However, as a naturally occurring and predictable event, childbirth provides a unique opportunity to study the development of posttraumatic stress reactions prospectively and to examine the role of the etiological factors involved [8, 9].

In the general trauma literature, pain has been found to be related to the development of PTSD [10, 11]. In the childbirth literature, however, the picture is less clear. Even though pain during delivery is a very common experience [12], it is not necessarily associated with the development of posttraumatic stress symptoms [8]. Consequently, some studies have found labor pain to be related to posttraumatic stress symptoms after childbirth [1, 13], whereas others have not [5, 8]. As opposed to other types of pain, which may indicate injury or illness, a unique and particular significance is assigned to labor pain [14], and the outcome—the baby—is normally a joyful one. Although pain intensity ratings are often high during labor, ratings of the affective dimension of pain (i.e., pain aversiveness) are typically lower [15]. The appraisal of pain and the overall birth experience may, therefore, be of greater importance than the intensity of the pain per se in relation to mental health outcomes after childbirth. However, to our knowledge these features have not been studied in relation to posttraumatic stress symptoms after childbirth. The importance of subjective appraisals for the experience outcome is a cornerstone of Richard S. Lazarus and colleagues' [16] transactional stress theory. According to the theory, only events appraised as being harmful or threatening will cause negative emotional consequences. Hence, subjective birth experiences are expected to be central in the development of posttraumatic stress symptoms after childbirth. In fact, in a previous study, our research team showed that subjective birth experiences were more important than actual labor complications in the development of posttraumatic stress symptoms after childbirth [17].

To our knowledge, no previous study has examined the role of labor pain and women's overall birth experience in a more comprehensive framework, taking into account important predisposing factors known to be related to posttraumatic stress symptoms after childbirth. The following predisposing factors have been suggested to be related to posttraumatic stress symptoms: earlier PTSD [18, 19], fear of childbirth [20-22], depression [19], and anxiety [1, 5, 23]. Taking relevant variables into account simultaneously allows estimation of the unique contribution of each of them.

Aim

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References

In this large-scale longitudinal study, we followed women from pregnancy through 8 weeks postpartum. Our aim was to investigate the role of labor pain and the overall birth experience in the development of posttraumatic stress symptoms in a comprehensive framework [3]. We hypothesized that a major part of the influence of labor pain on posttraumatic stress symptoms after childbirth is mediated by the overall birth experience.

Methods

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References

Participants

The study sample was drawn from the Akershus Birth Cohort (ABC), which targeted all women scheduled to give birth at Akershus University Hospital, located near Oslo, the capital of Norway, and serving approximately 350,000 people from both urban and rural areas. On average, 4,200 women give birth at the hospital's maternity ward each year.

Recruitment took place from November 2008 to April 2010. Mothers were recruited for the study when they had their routine fetal ultrasound examination, which is performed around gestational week 17. Of the eligible women (able to complete a questionnaire in Norwegian), 79 percent (N = 3,752) agreed to participate and returned the first questionnaire. Participants also completed questionnaires at pregnancy week 32 and 8 weeks postpartum, with response rates of 81 percent (2,936 out of 3,620) and 66 percent (2,217 out of 3,380), respectively. The number of eligible women dropped somewhat at pregnancy week 32 and 8 weeks postpartum, as some women had moved or were withdrawn from the study because of severe complications. An additional questionnaire was handed out to the women who gave birth between May 2009 and September 2010; 52 percent (1,244 out of 2,389) of the women included in the study answered. This questionnaire was handed out within 48 hours after delivery, but only to a part of the women included in the study, as it was not part of the original study design but added at a later time point.

For this study, we used information from all questionnaires and from the hospital's birth record. The birth record is completed by the hospital staff members and contains sociodemographic and medical information about the mother, child, pregnancy, and birth. We excluded women who underwent an emergency or elective cesarean section (N = 385 [8.3%] and N = 284 [6.1%], respectively), as they present a special population with regard to labor pain and subjective birth experiences.

The ABC study obtained ethical approval from the Regional Committees for Medical and Health Research Ethics, and all participants gave written informed consent.

Measures

Predisposing factors were measured during pregnancy at pregnancy week 17 (earlier symptoms of PTSD) and at pregnancy week 32 (fear of childbirth, symptoms of depression, and symptoms of anxiety). Labor pain and overall birth experience were measured within 48 hours after delivery. Posttraumatic stress symptoms after childbirth were measured at 8 weeks postpartum.

Posttraumatic stress symptoms after childbirth

The Impact of Event Scale was used to measure posttraumatic stress symptoms [24]. The Impact of Event Scale is a self-rating scale that measures symptoms of intrusion and avoidance. The scale has been validated in postpartum women [25] and can be used as a continuous or categorical measure with scores over 19 reflecting clinically significant distress, and scores above 34 indicating that PTSD is likely to be present [26].

In our multivariate analyses, we conducted a confirmatory factor analysis of the Impact of Event Scale. In these analyses, items were handled as ordered categorical variables to reflect uneven intervals among the response options of the items (see “Statistical Analyses”).

Labor pain

Labor pain was measured with the following question: “How much pain did you feel during labor?” The pain was measured with a numeric rating scale, which presents a common way of measuring pain [27]. The scale ranged from a minimum score of 0 to a maximum score of 10 (“no pain at all” to “the most intense pain imaginable”).

Overall birth experience

Overall birth experience was measured with the following question: “What was your overall experience of the birth?” It was measured with a numeric response scale, ranging from a minimum score of 0 to a maximum score of 10 (“very good” to “extremely bad”).

Predisposing factors

The participating women reported whether they had been involved in a dramatic and terrifying event at any time in their life. If this was the case, they reported whether they had suffered from eight potential symptoms related to that event during the past month. The symptoms were based on the questions about PTSD included in the Mini-International Neuropsychiatric Interview (M.I.N.I.). The M.I.N.I. is a short, structured clinical interview that enables researchers to make diagnoses of psychiatric disorders according to DSM-IV or ICD-10 [28].

Fear of childbirth was assessed using the Wijma Delivery Expectancy/Experience Questionnaire (W-DEQ, version A) [29]. This is the most frequently used instrument to measure fear of childbirth. The W-DEQ, version A, measures fear of childbirth as operationalized by the cognitive appraisal of the approaching delivery.

Symptoms of depression during the past week were measured by the Edinburgh Postnatal Depression Scale [30]. The Edinburgh Postnatal Depression Scale is a self-rating scale designed to identify postnatal depression. However, the scale has also been validated for use in pregnancy and with nonpostnatal mothers [31, 32].

Ten items from the Hopkins Symptom Check List were used to evaluate anxiety symptoms during the previous week. The Hopkins Symptom Check List is a widely used self-rating scale, and the first 10 items comprise the anxiety score (SCL-anxiety) [33, 34].

Statistical Analyses

Analyses were conducted in the framework of structural equation modeling [35]; we used the statistical program Mplus 7 (Muthén & Muthén, Los Angeles, CA, USA) for all analyses. A robust weighted least squares estimator (WLSMV) was employed, because the items of the posttraumatic stress symptoms after childbirth were considered to be ordered categorical variables [36].

First, a confirmatory factor analysis of the Impact of Event Scale was conducted, constructing one latent factor for the posttraumatic symptoms. As conducting confirmatory factor analyses on all predisposing factors would have led to an excessively complex model, they were treated as manifest variables, and sum scores were calculated for those variables. To create sum scores, missing values were substituted with the mean of each case if the number of missing items was 20 percent or less; otherwise, they were excluded from the analysis. Next, correlation analyses were conducted to study the bivariate associations. Finally, the entire mediation model was estimated, including the estimation of direct and indirect effects. Tests of mediation by means of Sobel's test [37] were conducted examining whether or not the indirect effects involving the putative mediator were statistically significant. In our multivariate model, missing data were accounted for by the missing routines for WLSMV in Mplus (Muthén & Muthén, Los Angeles, CA, USA), which are based on pairwise present analysis, assuming that the data are missing completely at random [36]. According to these routines, women had to have complete data on all exogenous variables (i.e., predisposing factors) to be included in the analyses; in addition, they had to have data on at least one of the endogenous variables (i.e., posttraumatic stress symptoms, labor pain or overall birth experience). This resulted in a final sample of 1,893 women.

Results

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References

Descriptives

Mean age at delivery was 31.1 years and approximately half of the women (48.9%) were first-time mothers. Most of the women (97.6%) were married or cohabitating and did not smoke at the time of delivery (95.7%). Educational level was as follows: 3.3 percent had 9 years (lower secondary school), 29 percent had 12 years (upper secondary school), and 67.7 percent had more than 12 years of education (higher education).

Marital status was not significantly related to attrition; however, women who had experienced birth complications and who were not working at the beginning of their pregnancy were less likely to fill in the third questionnaire. Furthermore, parity, smoking, lower educational level, and lower age was related to attrition in both the second and third questionnaire. Compared with national data from the Medical Birth Registry of Norway from 2009, the women in the study were less often smokers (4.3% vs 8.2% at the time of delivery), were slightly older (mean age of 31.1 vs 29.7), and fewer single women were present in the study (2.4% vs 9.6%) [38].

On average, participants scored low on postpartum posttraumatic stress symptoms after childbirth (Table 1). However, we found that 36 women (1.9%) scored above 34 on the Impact of Event Scale, which indicates a likely PTSD condition [26]. For the descriptive analyses, we used the suggested weightings of the items of the Impact of Event Scale and coded them 0, 1, 3, or 5 [24].

Table 1. Mean Scores and Medians of All Variables.
MeasuresMean (SD)Median
  1. SD = Standard deviation; PTSD = Posttraumatic stress disorder.

Posttraumatic stress symptoms (N =1,890)
Impact of Event Scale, total score6.73 (8.10)4.0
Impact of Event Scale, intrusion score4.28 (4.92)3.0
Impact of Event Scale, avoidance score2.39 (3.93)1.0
Labor pain (N = 1,149)8.54 (1.55)9.0
Overall birth experience (N = 1,149)2.75 (2.40)2.0
Predisposing factors
Symptoms of PTSD (N = 3,213)0.29 (0.82)0.0
Fear of childbirth (N = 2,515)56.10 (19.49)55.0
Symptoms of depression (N = 2,515)4.98 (4.18)4.0
Symptoms of anxiety (N = 2,514)12.86 (3.18)12.0

The women reported a high level of labor pain (mean = 8.54, SD = 1.55) and on average, the women had a good birth experience (mean = 2.75, SD = 2.40) (Table 1).

Bivariate Results

The confirmatory factor analysis supported that the Impact of Event Scale measures one single construct (comparative fit index [CFI] = 0.95, Tucker-Lewis Index [TLI] = 0.95, root mean square error of approximation [RMSEA] = 0.063).

Posttraumatic stress symptoms were significantly related to all variables included in the analyses. Labor pain and overall birth experience were also associated with each other (r = 0.24, p < 0.001). With respect to the predisposing factors, labor pain was weakly or not associated, whereas overall birth experience was significantly related to all predisposing factors (except symptoms of earlier PTSD), in particular to fear of childbirth (r = 0.31, p < 0.001) (see Table 2).

Table 2. Bivariate Correlations with Posttraumatic Stress Symptoms, Overall Birth Experience, and Labor Pain.
 Posttraumatic stress symptomsLabor painOverall birth experience
  1. a

    p ≤ 0.001.

  2. n.s. = not statistically significant.

Posttraumatic stress symptoms1.00  
Labor pain0.23a1.00 
Overall birth experience0.39a0.24a1.00
Symptoms of PTSD0.19a0.03 n.s.0.01 n.s.
Fear of childbirth0.37a0.06 n.s.0.31a
Symptoms of depression0.40a0.14a0.19a
Symptoms of anxiety0.36a0.13a0.19a

Multivariate Results

Labor pain was significantly related to posttraumatic stress symptoms even though overall birth experience was included as mediator in the model (standardized direct effect = 0.10). However, a substantial proportion (33%) of the total effect of labor pain on posttraumatic stress symptoms (i.e., sum of the direct and indirect effects) was mediated by overall birth experience (standardized total effect = 0.15, standardized indirect effect = 0.05, p < 0.001). Thus, overall birth experience partially mediated the effect of labor pain on posttraumatic stress symptoms. A part of the effect of fear of childbirth (standardized total effect = 0.23, standardized indirect effect = 0.07, p < 0.001) was also mediated by overall birth experience. However, the effect of the other predisposing factors was mediated by neither overall birth experience, nor by labor pain. (Fig. 1). This multivariate mediation model showed an acceptable fit (CFI = 0.93, TLI = 0.92, RMSEA = 0.045) and was, therefore, considered to be an appropriate model.

image

Figure 1. Relations between labor pain, overall birth experience and pre- and postpartum factors. Only the statistically significant pathways are depicted.

Download figure to PowerPoint

To examine the robustness of the results, the same multivariate model was additionally run using listwise deletion instead of pairwise present analysis. Results from the new analyses differed only slightly from those in the original analyses.

Discussion

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References

To our knowledge, this is the first longitudinal cohort study that investigates the role of labor pain and overall birth experience in the development of posttraumatic stress symptoms after childbirth in a comprehensive framework. The key findings are: (1) Posttraumatic stress symptoms were significantly related to both labor pain and overall birth experience. (2) In line with our hypothesis, a substantial portion of the effect of labor pain on posttraumatic stress symptoms was mediated by overall birth experience.

We found that 1.9 percent of the participants scored above 34 on the Impact of Event Scale, indicating a likely PTSD condition. This finding is consistent with previous findings that have found rates of 2–6 percent [3]. Likewise, the high level of labor pain that we found is in agreement with previous findings [12]. Although labor pain was related to posttraumatic stress symptoms, a third of the effect was accounted for by overall birth experience.

In a similar vein, in a qualitative study that investigated 20 women who had experienced their deliveries as traumatic, severe labor pain had a negative influence on their birth experience and was related to increased distress [39]. In fact, for 50 percent of the women, perceived pain was an indication that their own lives were being threatened [40]. Two other studies also found that labor pain increased feelings of distress, with the increased distress but not the pain itself being related to the development of posttraumatic stress symptoms [5, 38]. These findings suggest that experiencing pain is not necessarily harmful, but it may lead to catastrophic interpretations, which may be the reason why childbirth can be a traumatic experience with negative psychiatric consequences [8]. Therefore, in line with our results, these findings emphasize the role of the subjective birth experience. However, the studies referred to just above had a small sample size [40, 38], were confined to examining singular risk factors of posttraumatic stress [5], or studied a selected, clinical group of women [40], which limits their generalizability. In contrast, we tested a more comprehensive model using sophisticated methods with sufficient statistical power; this study therefore fills an important gap in the literature.

Clinical and Theoretical Implications

In Norway, a relatively small country, more than 60,000 births take place annually; a rate of 1.9 percent thus results in approximately 1,200 traumatized women each year. In addition, an even higher number of women suffer from posttraumatic symptoms after childbirth without qualifying for a clinical diagnosis. Recognizing the importance of women's birth experience opens up opportunities for prevention. Midwives may take on a significant role, as their task is to not only focus on the medical aspects of delivery but also take care of women in other aspects. Enough time and resources ought to be provided to midwives so that they can make women feel as safe and comfortable as possible. Furthermore, to prevent catastrophic interpretations of the pain and of what is going on, both physicians and midwives should continue to give women reassuring information, before and during delivery.

Our findings offer additional support to Lazarus' transactional stress theory. To understand variations among individuals under comparable stress conditions, we must take into account the subjective appraisal that mediates between the stress experience and the subsequent emotional reaction [16]. During childbirth, almost all women experience a high level of pain [12]. However, according to Lazarus' transactional stress theory, whether or not a woman develops posttraumatic stress symptoms after childbirth would be strongly influenced by her subjective birth experience and her appraisal of the labor pain. As this theory could be supported, this prospective study contributes to the general PTSD literature as well, highlighting the importance of the subjective experience of a potentially traumatic event.

Limitations

Readers should also note some limitations to our findings. First, we did not differentiate between the sensory and affective dimensions of pain. The sensory dimension encompasses the perception of the location, intensity, and quality of pain, whereas the affective dimension of pain refers to the unpleasantness inherent to pain [41]. When pain is perceived to be associated with a serious threat to health or life, the affective dimension of pain is rated higher than when the pain is less frightening, even when sensory-intensity ratings are identical [15]. As the affective dimension of pain is more intimately related to emotions, it is likely that independent measurement of these two aspects of pain would reveal that the affective dimension is of greater importance for posttraumatic stress symptoms after childbirth. However, although we recognize this limitation, the independent measurement of these components is unlikely to be successful without thorough instruction of the participants, which was not possible within the context of this study.

Second, birth is complex and an event that may last 24 hours or more, involves more than one location, interactions with multiple health care professionals and loved ones, and various decision-making episodes. Nevertheless, we assessed birth experience only with a single item. Even though this item functioned well and had a high predictive value, our results are not able to determine the specific aspects of birth experience that are crucial. For instance, support during birth, particularly for women with a history of prior trauma, has been suggested to protect against the development of posttraumatic stress symptoms [42]. In addition, we previously found that feeling taken care of and being afraid during birth were essential parts of the women's birth experience, which in turn predicted the development of posttraumatic stress symptoms [17]. Future work ought to use a more comprehensive measure to provide further insights into the specific areas of birth experience that confer protective effects.

Third, only 52 percent filled in the questionnaire that was handed out at the maternity ward. Modern techniques for handling of missing data were applied to ensure reliable results [36] and similar results were found when applying a different approach to handle missing data. However, estimates may be somewhat biased because of missingness, particularly as data used in the study were not missing completely at random [43].

Finally, generalizability of the results is limited by the fact that only Norwegian-speaking women were included and that this study relates to vaginal deliveries only. Furthermore, with regard to sociodemographic characteristics, it is reasonable to believe that a slight social gradient associated with participation is present. However, it is important to bear in mind that selection bias does not necessarily influence the results when associations between variables are investigated [44].

Conclusion

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References

Although the results of this study show that both labor pain and overall birth experience play a role in the development of posttraumatic stress symptoms after childbirth, overall birth experience appears to be the central factor. Overall birth experience is not only considerably related to posttraumatic stress symptoms directly but also mediates a substantial portion of the effect of labor pain on posttraumatic stress symptoms.

Being aware of the essential role of women's birth experiences offers a unique opportunity as an important step to prevent traumatization. Future work should therefore address which areas of birth experience confer protective effects on women to improve clinical care.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References

The authors thank the women who volunteered their time to participate in this study. We also thank Tone Breines Simonsen, Wenche Leithe and Ishtiaq Khushi for assistance in the data collection.

Ethics Approval

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References

The study was approved by the Regional Committee for Ethics in Medical Research in Norway, approval number S-08013a.

References

  1. Top of page
  2. Abstract
  3. Aim
  4. Methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgments
  9. Ethics Approval
  10. References
  • 1
    Soet JE, Brack GA, DiIorio C. Prevalence and predictors of women's experience of psychological trauma during childbirth. Birth 2003;30(1):3646.
  • 2
    Creedy DK, Shochet IM, Horsfall J. Childbirth and the development of acute trauma symptoms: Incidence and contributing factors. Birth 2000;27(2):104111.
  • 3
    Slade P. Towards a conceptual framework for understanding post-traumatic stress symptoms following childbirth and implications for further research. J Psychosom Obstet Gynecol 2006;27(2):99105.
  • 4
    McDonald S, Slade P, Spiby H, et al. Post-traumatic stress symptoms, parenting stress and mother-child relationships following childbirth and at 2 years postpartum. J Psychosom Obstet Gynecol 2011;32(3):141146.
  • 5
    Czarnocka J, Slade P. Prevalence and predictors of post-traumatic stress symptoms following childbirth. Br J Clin Psychol 2000;39(Pt 1):3551.
  • 6
    Gottvall K, Waldenstrom U. Does a traumatic birth experience have an impact on future reproduction? BJOG 2002;109(3):254260.
  • 7
    American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. Washington DC: American Psychiatric Press, 2000.
  • 8
    Olde E, van der Hart O, Kleber R, et al. Posttraumatic stress following childbirth: A review. Clin Psychol Rev 2006a;26(1):116.
  • 9
    Ayers S, Pickering AD. Do women get posttraumatic stress disorder as a result of childbirth? A prospective study of incidence. Birth 2001;28(2):111118.
  • 10
    Fedoroff IC, Taylor S, Asmundson GJG, et al. Cognitive factors in traumatic stress reactions: Predicting PTSD symptoms from anxiety sensitivity and beliefs about harmful events. Behav Cognitive Psycho 2000;1:515.
  • 11
    Schreiber S, Galai-Gat T. Uncontrolled pain following physical injury as the core-trauma in the post-traumatic stress disorder. Pain 1993;1:107110.
  • 12
    Lally JE, Murtagh MJ, Macphail S, et al. More in hope than expectation: A systematic review of women's expectations and experience of pain relief in labour. BMC Med 2008;6:7.
  • 13
    Stramrood CA, Paarlberg KM, Huis In ‘t Veld EM, et al. Posttraumatic stress following childbirth in homelike- and hospital settings. J Psychosom Obstet Gynecol 2011;32(2):8897.
  • 14
    Eberhard J, Stein S, Geissbuehler V. Experience of pain and analgesia with water and land births. J Psychosom Obstet Gynecol 2005;26(2):127133.
  • 15
    Price DD, Harkins SW, Baker C. Sensory-affective relationships among different types of clinical and experimental pain. Pain 1987;28(3):297307.
  • 16
    Lazarus RS, Folkman S. Stress, Appraisal, and Coping. New York: Springer, 1984.
  • 17
    Garthus-Niegel S, von Soest T, Vollrath ME, et al. The impact of subjective birth experiences on post-traumatic stress symptoms: A longitudinal study. Arch Womens Ment Health 2013;16(1):110.
  • 18
    Ayers S, Harris R, Sawyer A, et al. Posttraumatic stress disorder after childbirth: Analysis of symptom presentation and sampling. J Affect Disord 2009;1–3:200204.
  • 19
    Cohen MM, Ansara D, Schei B, et al. Posttraumatic stress disorder after pregnancy, labor, and delivery. J Women's Health 2004;13(3):315324.
  • 20
    Soderquist J, Wijma K, Wijma B. Traumatic stress after childbirth: The role of obstetric variables. J Psychosom Obstet Gynecol 2002;23(1):3139.
  • 21
    Soderquist J, Wijma K, Wijma B. Traumatic stress in late pregnancy. J Anxiety Disord 2004;18(2):127142.
  • 22
    Wijma K, Soderquist J, Wijma B. Posttraumatic stress disorder after childbirth: A cross sectional study. J Anxiety Disord 1997;11(6):587597.
  • 23
    Keogh E, Ayers S, Francis H. Does anxiety sensitivity predict post-traumatic stress symptoms following childbirth? A preliminary report. Cognitive Behav Therapy 2002;4:145155.
  • 24
    Horowitz M, Wilner N, Alvarez W. Impact of Event Scale: A measure of subjective stress. Psychosom Med 1979;41(3):209218.
  • 25
    Olde E, Kleber RJ, van der Hart O, et al. Childbirth and posttraumatic stress responses: A validation study of the Dutch Impact of Event Scale-Revised. Euro J Psychol Assess 2006b;22(4):259267.
  • 26
    Neal LA, Busuttil W, Rollins J, et al. Convergent validity of measures of post-traumatic stress disorder in a mixed military and civilian population. J Trauma Stress 1994;7(3):447455.
  • 27
    Jensen MP, Karoly P. Self report scales and procedures for assessing pain in adults. In: Turk DC, Melzack R, eds. Handbook of Pain Assessment. New York: The Guilford Press, 2011.
  • 28
    Sheehan DV, Lecrubier Y, Sheehan KH, et al. The Mini-International Neuropsychiatric Interview (M.I.N.I): The development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. J Clin Psychiatry 1998;59(Suppl 20):33.
  • 29
    Wijma K, Wijma B, Zar M. Psychometric aspects of the W-DEQ; a new questionnaire for the measurement of fear of childbirth. J Psychosom Obstet Gynecol 1998;19(2):8497.
  • 30
    Cox JL, Holden JM, Sagovsky R. Detection of postnatal depression. Development of the 10-item Edinburgh Postnatal Depression Scale. Br J Psychiatry 1987;150:782786.
  • 31
    Eberhard-Gran M, Eskild A, Tambs K, et al. The edinburgh postnatal depression scale: validation in a Norwegian community sample. Nord J Psychiatry 2001;55(2):113117.
  • 32
    Murray D, Cox JL. Screening for depression during pregnancy with the edinburgh depression scale (EPDS). J Repro Infant Psychol 1990;8(2):99107.
  • 33
    Nettelbladt P, Hansson L, Stefansson CG, et al. Test characteristics of the Hopkins Symptom Check List-25 (HSCL-25) in Sweden, using the Present State Examination (PSE-9) as a caseness criterion. Soc Psychiatry Psychiatr Epidemiol 1993;28(3):130133.
  • 34
    Eberhard-Gran M, Tambs K, Opjordsmoen S, et al. A comparison of anxiety and depressive symptomatology in postpartum and non-postpartum mothers. Soc Psychiatry Psychiatr Epidemiol 2003;38(10):551556.
  • 35
    Bollen KA. Structural Equations with Latent Variables. New York: Wiley, 1989.
  • 36
    Muthén LK, Muthén BO. Mplus User's Guide. Los Angeles, CA: Muthén & Muthén, 2012.
  • 37
    Sobel ME. Asymptotic confidence intervals for indirect effects in structural equations models. In: Leinhart S, ed. Sociological methodology. San Francisco, CA: Jossey-Bass, 1982:290312.
  • 38
    Lyons S. A prospective study of post traumatic stress symptoms 1 month following childbirth in a group of 42 firsttime mothers. J Repro Infant Psychol 1998;16:91105.
  • 39
    Norwegian Institute of Public Health. Medical Birth Registry of Norway. Oslo, Norway: Norwegian Institute of Public Health, 2013.
  • 40
    Allen S. A qualitative analysis of the process, mediating variables and impact of traumatic childbirth. J Repro Infant Psychol 1998;2–3:107131.
  • 41
    Price DD. Psychological and neural mechanisms of the affective dimension of pain. Science 2000;288(5472):17691772.
  • 42
    Ford E, Ayers S. Support during birth interacts with prior trauma and birth intervention to predict postnatal post-traumatic stress symptoms. Psychol Health 2011;26(12):15531570.
  • 43
    Muthén BO, Kaplan D, Hollis M. On structural equation modeling with data that are not missing completely at random. Psychometrika 1987;52(3):431462.
  • 44
    Nilsen RM, Vollset SE, Gjessing HK, et al. Self-selection and bias in a large prospective pregnancy cohort in Norway. Paediatr Perinat Epidemiol 2009;23(6):597608.