Epidemiologic data from around the world show that depression is approximately twice as common in women than men and that its first onset peaks during the child‐bearing years.1 Pregnancy, miscarriage or fetal death, infertility, and the postpartum period may especially challenge a woman's mental health. Postpartum depression, which often resembles other forms of major depression, affects 10–20% of all mothers.2–11 It may have a deleterious effect on the woman's social and personal adjustment, the marital relationship, and the mother‐infant interaction. Furthermore, there is a 30–50% risk of relapse of depression in a future pregnancy.1,12
Maternal depression early in the infant's life may affect the child's psychologic development with significant intellectual deficits as a result.13–15 Other consequences for the child include higher risk of accidents, sudden infant death syndrome, and a higher frequency of hospital admissions.16–18 Various explanatory models on the etiology have been proposed; probably postpartum depression is a result of an interaction between genetic vulnerability, hormonal changes, and major life events.19–22 Recent studies have focused on psychosocial stressors and previous psychiatric history in a woman's life as major risk factors for developing postpartum depression.23–27 The literature concerning obstetric and perinatal risk factors is sparse and shows little concordance.2,8,28,29 The hypothesis of this study was that complications during pregnancy, delivery, and/or the perinatal period are associated with an increased risk of postpartum depression.
MATERIALS AND METHODS
The Swedish antenatal health care system reaches almost 100% of all pregnant women (Swedish National Board of Health and Welfare). The antenatal care clinics provide regular check‐ups on the physical and psychologic health during pregnancy and puerperium. The same percentage, as above, is valid for deliveries as there are no private maternity hospitals in Sweden and home deliveries are rare.
The original sample in the present study comprises the total population of pregnant women consecutively registered at the antenatal care clinics in four communities in the southeast region of Sweden.11 Enrollment took place in separate 3‐month periods for each of the four communities during 1997–1999. The eligible women were approached in gestational weeks 35–36 and received both written and oral information from their midwife before giving consent. A total of 1558 women were approached. Sixty‐nine (4.4%) women declined to participate in the original study. The prevalence of depressive symptoms did not differ between the communities within each assessment. Out of 1489 women, all women with depressive symptoms on the Edinburgh Postnatal Depression Scale at 6–8 weeks and/or 6 months postpartum from two of the four communities were selected as an index group (n = 132). As control group, 264 women without depressive symptomatology on the Edinburgh Postnatal Depression Scale were randomly chosen from all four communities. Records from three index women and two control women were not found. One woman in the control group delivered a dead infant and was therefore excluded.
The Edinburgh Postnatal Depression Scale is a 10‐item self‐report scale, specifically designed to screen for postpartum depression in community samples.30 Each item is scored on a 4‐point scale (0–3), the minimum and maximum total score ranging from 0 to 30, respectively. The scale rates the intensity of depressive symptoms present within the previous 7 days. Five of the items are concerned with dysphoric mood, two with anxiety, and one each with guilt, suicidal ideas, and “not coping.” The Edinburgh Postnatal Depression Scale has been translated into at least 11 languages,31 including Swedish.32 Validity of the Swedish version has been tested, and the findings were identical or similar to earlier studies.9,10 Cox et al30 proposed a cutoff level of 10 if the test is to be used for screening purposes in the postpartum period. The Edinburgh Postnatal Depression Scale cannot confirm a diagnosis of depressive illness, but when selecting this threshold, the sensitivity for the detection of major depression was almost 100% and the specificity 82%.33 The Edinburgh Postnatal Depression Scale is easy to administer, takes only a few minutes to complete, and is well accepted by the women and the staff. In this study, the cutoff level of 10 was used as the dependent variable. The prevalence of depressive symptoms, an Edinburgh Postnatal Depression Scale score of 10 or more, was 13% at the 6–8 weeks assessment and unaltered at 6 months postpartum.11
All data related to the pregnancy, delivery, and the puerperium were registered in the standardized and identical Swedish antenatal, delivery, and neonatal records. The data were manually extracted from the records by the main author (AJ), and are thus prospectively related to the development of depressive symptoms. In multiparas, medical records from earlier deliveries were also scrutinized. The following data were collected: age, parity, marital status, occupation, and number of induced abortions, miscarriages, or extrauterine pregnancies. Any history of infertility, psychiatric disorder, or obstetric complications, actual chronic medical diseases, number of visits at the antenatal care clinics before delivery (midwife and physician), pregnancy complications, sick leave during pregnancy, and perinatal events were obtained.
All analyses were done using the SPSS program 10.1 (SPSS Inc., Chicago, IL). Statistical significance was defined as two‐sided P values using a significance level of 5%. Differences were tested with Student t test for normally distributed continuous variables and the Mann‐Whitney U test for continuous variables not normally distributed. Odds ratios, presented with 95% confidence intervals, were calculated for categoric variables. Logistic regression with conditional stepwise backward elimination was used when multiple variables were considered simultaneously. The dependent variables were depressed or nondepressed. The explanatory variables were sociodemographic data, medical, gynecologic, and obstetric history, pregnancy, delivery, and neonatal data. The study was approved by the Regional Ethics Committee for Human Research of the Faculty of Health Sciences, Linköping University (No. 97133).
Distributions of independent variables are shown in Tables 1–5. The sociodemographic variables are shown in Table 1. No differences were found between women with or without a depressive symptomatology.
In Table 2, we describe earlier medical history with focus on gynecologic and obstetric data. Women with an earlier history of two or more abortions and a history of earlier obstetric complications, mainly acute cesarean section and instrumental delivery, were significantly more prone to develop depressive symptoms postpartum.
Complications during the present pregnancy (Table 3), such as hyperemesis, premature contractions, and psychiatric disorder, were more common in the postpartum depressed group of women. Number of visits at the antenatal care clinics and number of women on sick leave were also more frequent in this group (Table 3).
Concerning delivery data, presented in Table 4, no differences were found, except from intrapartal analgesia with morphine analogues. As the women included in this study were enrolled in pregnancy weeks 35–36, there are no premature deliveries in the sample. Women with postpartum depressive symptoms stayed longer at the hospital after delivery but did not have a higher frequency of complicated puerperium than nondepressed women (Table 5). Women who gave birth to babies with congenital major malformations were also more depressed than the others were (Table 5). Subsequent multivariable analysis is shown in Table 6. Sick leave during pregnancy and number of visits at the antenatal care clinic are the variables with the strongest association to postpartum depressive symptoms for all women. To facilitate comparisons, multivariable analyses were performed for multiparas and primiparas, respectively, but no further information was gained.
In this population‐based case‐control study, information regarding a wide range of potential risk factors was collected. An advantage of this study is the fact that we had reached the total pregnant population at the time of the study and that all data were extracted from standardized medical records and not from maternal recall. To our knowledge, this is the only study that includes earlier medical, gynecologic, and obstetric history. Most of the predictors found were obvious already during pregnancy, which could facilitate planning of prevention and intervention in the future.
The strongest risk factors for postpartum depressive symptoms were sick leave during pregnancy and a high number of visits to the antenatal care clinic. The reasons for sick leave were mainly psychiatric disorders and pregnancy‐related complications. However, a potential weakness in this study might be an underestimation of an earlier or ongoing psychiatric condition influencing the results. Nevertheless, this result supports our hypothesis that pregnancy complications are risk factors for postpartum depression.
Hyperemesis and premature contractions were more common in the postpartum depressed group of women. Explanatory models for these symptoms might be somatization of pregnancy‐related anxiety or depression but might also be an effect of hormonal changes in the pregnant woman. Antenatal depressive symptoms and postpartum depression are correlated,11,31 but whether this is on a psychosocial basis or a result of hormonal and genetic vulnerability remains to be investigated. The absence of correlation between sociodemographic variables and depressive symptoms is in line with previous studies.2,3 The risk factors identified in the gynecologic and obstetric history were two induced abortions or more and among multiparas a history of acute cesarean section or instrumental delivery in the past. These risk factors did not remain significant on the multivariable level. We found no association between delivery complications and the development of depressive symptoms. This is consistent with the findings in two recent studies,29,34 but not with some earlier studies, which have reported a strong link between cesarean section and postpartum depression.28,35
Our results show that women at risk for postpartum depression can be identified during pregnancy. The strongest risk factors, sick leave and a high number of visits at the antenatal care clinics, are not etiologic and might be of either behavioral or biologic origin. The possibilities of genetic vulnerability and hormonal changes ought to be investigated further to reach a more thorough understanding.
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© 2002 The American College of Obstetricians and Gynecologists
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