Even though pregnancy is a period of emotional well-being in many women, some women, when pregnant, experience their first depressive episode, whereas others, with a history of depression, are at risk for its recurrence,1–4 suggesting that pregnant women show the same risk for depression as other women of child-bearing age.5,6
Nevertheless, the estimated prevalence of depression throughout pregnancy has ranged from 8% to 51%.2 This large range might be explained by the different methodologies used in assessing and diagnosing depression. The prevalence is higher when depressive symptoms rather than disorders are investigated,1 when depression is assessed by self-reported rating scales rather than structured clinical interview,1 and when operational criteria are not used for the diagnosis.1 The difficulty in distinguishing between somatic complaints (such as fatigue and appetite change), commonly found in pregnancy and depressive symptoms7 may also contribute to the aforementioned discrepancy. Finally, the time of assessment is also relevant in the estimation of prevalence of depression, because different estimates can be obtained depending on single or multiple evaluations throughout pregnancy.2
Concerning this latter issue, multiple time of assessment, compared with a single evaluation, offers the advantage to detect prevalence more precisely and to obtain information whether it varies throughout pregnancy: ie, some studies, using a more rigorous methodology, suggest that depression is higher in the first trimester.2 The consequences of depression not only for women but also for the fetus and the family4,8 makes this information particularly useful in the clinical management of this condition. Finally, when risk factors for developing depression were investigated,9 no previous study evaluated whether major and minor depression were predicted by different predictors, as we searched PubMed in all languages from January 1980 to September 2009 using the key words major depression, minor depression, pregnancy, antenatal, and risk. Therefore, the aim of the present study was to evaluate the time to onset, duration, and risk factors for minor and major depression in pregnant women attending the Centres for Prenatal Care.
MATERIALS AND METHODS
The study protocol was approved by the local ethical committee (Comitato Etico Azienda Sanitaria Locale di Mantova). The study population was recruited among women who consecutively sought assistance at the Centers for Prenatal Care of the Public Health Service of District of Mantova (Italy), from September 2005 to August 2006.
Women participated in the study after the procedure had been fully explained and a written informed consent was obtained, if they were aged older than 18 years and completed all the evaluations from the beginning of their pregnancy. At each visit, all women were asked to complete (approximately every month) the following evaluations: 1) the Italian translation of the Primary Care Evaluation of Mental Disorders (PRIME-MD),10 for the screening of depressive disorders; 2) the Italian translation of the hospital anxiety and depression scale (HADS)11 for the evaluation of severity of anxious and depressive symptoms.
All women completed a brief questionnaire, performed ad hoc, to collect sociodemographic and anamnestic information and to evaluate the presence (or absence) of problems with husband or partner, family, job, and family support and whether the pregnancy was unwanted. The results of the questionnaire were discussed with the women (and when available, with family members) to confirm their answers.
The PRIME-D is a structured interview for the diagnosis of mental disorders according to the criteria of DSM-IV,12 and was administered at each visit by the gynecologists, who were trained by a senior psychiatrist. The measure evaluates the presence of nine depressive symptoms in the last 2 weeks. Each symptom is rated on a four-point scale (from “not at all” to “most of the days”). Moreover, the difficulty in the daily functioning because of the depressive symptoms is also rated on a four-point scale (from “not at all” to “extremely difficult”). The assessment generally lasts 20 minutes. The PRIME-MD showed good specificity (98%) and sensitivity (73%) in detecting major depression in primary care.10
A woman was defined as depressed if, at any evaluation during pregnancy, 1) she fulfilled the criteria for major depression if in the last 2 weeks at least five depressive symptoms, of which one could be depressed mood or loss of pleasure, were present for “more than half of the days” or “almost all the days” and they made the daily functioning “very difficult” or “extremely difficult”; or 2) she fulfilled the criteria for a minor depression if in the last 2 weeks at least two and fewer than five depressive symptoms, of which one could be depressed mood or loss of pleasure, were present for “more than half of the days” or “almost all the days” and they made the daily functioning “very difficult” or “extremely difficult.”
A woman was defined as nondepressed if she did not satisfy the criteria for major depression or minor depression at any evaluation during pregnancy. A woman affected by both major and minor depression was only considered in the group of major depression subjects.
The duration and onset (the month in which depressive symptoms first satisfied the diagnostic criteria for major or minor depression) of depression throughout pregnancy were calculated. In women who showed depressive symptoms at the first evaluation, the onset was arbitrarily considered the first month of pregnancy. When major depression was preceded by minor depression, the onset of major depression was considered the month in which the diagnostic criteria were satisfied.
The HADS is a 14-item self-administered instrument for the evaluation of anxiety and depression in a nonpsychiatric population. Each item is rated on five-point (0–4) scale. The seven items of the depression subscale were largely based on the anhedonic state; in fact, five items are related to the loss of pleasure. The seven items of the anxiety subscale were chosen from the psychic manifestations of anxiety. Therefore, HADS generates two subscale scores: the anxiety score and the depression score.
A score higher than 10 for both subscales defines the presence of depression or anxiety. A high correlation was observed between anxiety and depression evaluated with HADS and clinical interview (0.54 and 0.79, respectively).
Concerning treatment of depression, only women with depressive symptoms severe enough (on clinical judgment) to represent a risk for the health of the mother and the fetus (severe loss of appetite with very low caloric intake, severe insomnia, agitation, or suicide ideation) were referred by the gynecologist to a psychiatrist for treatment. The gynecologists were properly trained to recognized this severe condition.
Comparisons among women with major depression and minor depression and nondepressed women were performed using a one-way analysis of variance with Bonferroni post-hoc analysis for continuous variables and with Fisher exact test for categorical variables.
Stepwise logistic regression was used to evaluate which variables at the beginning of pregnancy could predict the development of depression. Two regression analyses were performed; the same independent variables entered in both analyses were occupation, number of sons, presence of problems with husband or partner, family, or job, presence of family support, and whether the pregnancy was unwanted, whereas the dependent variables were major depression and no depression in one analysis and minor depression and no depression in the other analysis. The statistical software package SPSS 14.0 (SPSS Inc., Chicago, IL) was used for all data analyses.
During the study period, 193 women attended the Centres of Prenatal Care. Twenty-two women (11.3%) were not included in the study because of language problems (n=12) or refusal to participate (n=10). Among the remaining 171 women, 17 (9.9%) were excluded from the study because they did not attend all the visits throughout pregnancy. Among noncompleters, 10 dropped out after the first evaluation, five attended another visit, and two attended two more visits. At the beginning of pregnancy, the 17 noncompleters showed the same sociodemographic features as the completers. Moreover, none of the noncompleters showed depressive symptoms at any evaluation they attended. Therefore, the study completers were 154 women with a mean age±standard deviation of 30.8±4.4 years (range 18–44 years), and they were assessed for 6.2±0.5 times (range 6–8 times) during pregnancy.
Major depression was diagnosed in 19 women (12.3%) and minor depression in 28 (18.1%), whereas the remaining 107 women did not show any depressive symptoms (controls). In five women, minor depression symptoms preceded (n=3) or followed (n=2) major depression.
Women with major and minor depression and control women showed the same age, education, and family status, whereas a higher rate of housewives was found in women with major and minor depression than in controls (Table 1).
Moreover, women with major depression had a greater number of sons and more frequent conflict with husband or partner than women with minor depression and controls, whereas no difference in the rate of family and job problems, presence of family support, and unwanted pregnancy was observed among the groups of women (Table 1). Finally, the number of previous depressive episodes was greater in women with major and minor depression than in controls (Table 1).
Depression showed a later onset and a longer duration in women with major depression (5.6±2.8 months and 2.3±1.7 months, respectively) than in women with minor depression (3.5±2.2 months and 1.6±0.7, respectively; t=2.8, P=.007 and t=2.0, P=.04) (Table 2). Among depressed women, five showed depressive symptoms at the first evaluation (one was affected by major depression and four by minor depression), whereas eight were still depressed at the last evaluation before delivery (six affected by major depression and two by minor depression) (Table 2).
Concerning treatments, no depressed women were treated with antidepressants or other psychotropic drugs. Only two women with major depression received psychological support.
When women with major depression were compared with nondepressed women using stepwise logistic regression, the risk of developing major depression was predicted at the beginning of pregnancy by the presence of previous depressive episode (χ2=14.0; P<.001; OR [odds ratio] 9.5, 95% confidence interval [CI] 2.5–29.2) and conflict with the husband/partner (χ2=3.7; P=.05; OR 7.8, 95% CI 1.02–62.7), whereas family status, unwanted pregnancy, problems with the family or the job and family support did not show any effect (Table 3). When women with minor depression were compared with nondepressed women, the risk of developing minor depression was predicted at the beginning of pregnancy by being a housewife (χ2=12.1; P<.001; OR 7.2, 95% CI 2.3–22.1), presence of previous depressive episode (χ2=6.7; P=.01; OR 4.7, 95% CI 1.4–15.3) and whether the pregnancy was unwanted (χ2=4.0; P=.04; OR 2.4, 95% CI 1.0–5.7), whereas problems with the husband or partner, family, or job and family support did not show any effect.
To our knowledge, this is the first prospective study investigating the presence of major depression and minor depression nearly at monthly intervals throughout pregnancy. The frequent assessment of depression (6.2±0.5 times) gave the possibility to evaluate the duration of the depressive episode and to verify whether the prevalence of major depression or minor depression varied during pregnancy.
In our sample, 47 women (30.5%) were diagnosed as affected by a depressive episode, 19 by major depression (12.3%) and 28 by minor depression (18.2%).
Concerning major depression, the prevalence (12.3%) observed in our sample confirms the data of a recent review,2 which reported 12.7% as the best estimation of major depression prevalence during pregnancy. Interestingly, in our study major depression lasted during pregnancy for a short time in the majority of affected women, because 63% of them showed major depression symptoms for two months or less. Moreover, the severity of depressive symptoms were mild, because the highest mean score of the HADS depression items observed in women with major depression was 12.4±2.9, only two points higher than the cutoff score.11 Therefore, these two findings, together with the observation that only two women received treatment for depression (psychological support), suggest that in most of our pregnant women with major depression, a depressive episode was present in mild form (short duration and mild severity).
In our women with major depression, the depressive episode occurred more frequently during the third (42%) and the first (37%) trimester of pregnancy, suggesting that the months preceding delivery and the first months after conception were the periods of pregnancy at major risk for depression. In the light of this finding, it may be supposed that in more vulnerable women, major depression can occur when the effect of stressor (pregnancy)13 probably exerts its highest effect (the months before the birth of the neonate) and at the begin of its action (first months of pregnancy) when women have difficulty managing the new life event.
In six women, major depression symptoms were still present at the last evaluation before delivery, leaving open the possibility that major depression symptomatology could last even during the postpartum period. This finding can confirm the suggestion that postpartum depression frequently begins during pregnancy.4,14–17
Women at high risk of major depression were those with a previous depressive episode (OR 9.5, 95% CI 2.9–30.8) and those with a problematic relationship with husband or partner (OR 7.8, 95% CI 1.02–62.7).Our study confirms that women with a previous major depression episode are more vulnerable to a recurrence when pregnant.3,4,18,19 Both biologic and psychological mechanisms (ie, pregnancy represents a major physiologic and psychological life event) might be involved in the major depression recurrence during pregnancy.4,13,20
The family environment is important for women to facilitate a good adaptation to pregnancy. Our study suggests that a problematic relationship with the husband or partner represents an additional stress, which reduces the possibility of women adequately managing pregnancy and confirms the data of previous studies that observed that marital satisfaction protected against depression during pregnancy.4,9,21–25
Concerning minor depression, minor depression was diagnosed in 18% of women. Even though our finding confirms the prevalence of minor depression found in the general population26,27 and in a recent study19 investigating antenatal depression with the PRIME-MD, our data are higher than the best estimation of prevalence of minor depression in pregnancy observed in previous prospective studies (5.7%).2 This difference can be explained by the combined effect of two variables: 1) the different number of assessments of depression during pregnancy in our study (six or more) compared with those of the previous studies (approximately three) and 2) the short duration of minor depression observed in our study (1.6±0.7 months). The short duration of minor depression (one month in 57% of cases) implies that its true prevalence can be evaluated only with frequent assessment (monthly). Therefore, only a few evaluations (ie, once per trimester) could not produce the best estimation of the prevalence of minor depression during pregnancy. This seems particularly true during the first trimester of pregnancy, because the onset of depression occurred in the first trimester in 60% of our women with minor depression and it lasted a short time (one month in 53% of women showing minor depression in the first trimester).
A previous study28 suggests that in nonpregnant women, minor depression may represent a prodromal or a residual phase of major depression. In our study, this condition was infrequent, because in most women with minor depression, depressive symptoms occurred independently from a major depression episode. Nevertheless, during the third trimester, some women with minor depression were still depressed at the last evaluation, supporting the hypothesis that the minor depression symptoms may represent a prodromal phase of a major depression to occur in the postpartum period, which frequently begins during pregnancy.4,14–17,19
At the beginning of pregnancy, risk factors for the development of minor depression were being a housewife (OR 7.2, 95% CI 2.3–22.1), the presence of previous depressive episode (OR 4.7, 95% CI 1.4–15.3), and an unwanted pregnancy (OR 2.4, 95% CI 1.0–5.7).
The high risk for depression observed in our pregnant housewives was difficult to explain, because these women have been protected from the negative effect of the conflicting roles of mother and worker on coping with pregnancy. The increase of responsibilities and dependency from husband or partner, the work overload, and the lack of time for themselves might be some of the factors associated with depression in pregnant housewives. Nevertheless, our finding confirms the data of previous articles that found that household work was associated with depression in pregnant23,24 and in nonpregnant women.29
The women more vulnerable to minor depression were also those who previously experienced a depressive episode, as suggested by other studies,3,4,18 and those who did not plan pregnancy, as reported by previous studies.4,9,30 These two findings, together with the data concerning the onset of minor depression in the first trimester in most women (60%), suggest that minor depression may represent in many pregnant women a psychological reaction to an unexpected life event (pregnancy) combined with a vulnerability to depression (having a history of depression). This psychological reaction resolves in just a short time without treatment (no women with minor depression received any treatment for depression), because minor depression lasted 2 months or less in 82% of women showing depression in the first trimester. This finding suggests that the initial difficulty in accepting the unwanted pregnancy subsides with the progression of pregnancy, and women can cope with the actual event.
Some methodologic aspects limit the generalization of our results. First, results from our study were analyzed using data from completers, and therefore the effect of dropouts on the estimation prevalence could not be evaluated. Nevertheless, the attrition rate in our study was 10%, which seems low, considering the high number of assessments. Probably the high rate of acceptance was obtained in our study because the evaluations were conducted by the health professional (gynecologists) that the women had a relationship with.
Second, major depression or minor depression were not diagnosed by a psychiatrist and therefore our data might have poor reliability. However, the depressive episode was diagnosed using the PRIME-MD, an interview performed to evaluate mental disorders in primary care, which showed a good reliability between diagnoses obtained by trained physicians and those obtained by psychiatrists.10 Moreover, the PRIME-MD showed good specificity and sensitivity in detecting major depression in primary care.10
Third, given the small sample size of our depressed women, firm conclusions should be drawn from our results with caution, and the present data need to be verified by using larger samples.
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