Cohort study of depressed mood during pregnancy and after childbirth.

Abstract

Objective To follow mothers' mood through pregnancy and after childbirth and compare reported symptoms of depression at each stage.

Design Longitudinal cohort study.

Setting Avon.

Participants Pregnant women resident within Avon with an expected date of delivery between 1 April 1991 and 31 December 1992.

Main outcome measures Symptom scores from the Edinburgh postnatal depression scale at 18 and 32 weeks of pregnancy and 8 weeks and 8 months postpartum. Proportion of women above a threshold indicating probable depressive disorder.

Results Depression scores were higher at 32 weeks of pregnancy than 8 weeks postpartum (difference in means 0.88, 95% confidence interval 0.79 to 0.97). There was no difference in the distribution of total scores or scores for individual items at the four time points. 1222 (13.5%) women scored above threshold for probable depression at 32 weeks of pregnancy, 821 (9.1%) at 8 weeks postpartum, and 147 (1.6%) throughout. More mothers moved above the threshold for depression between 18 weeks and 32 weeks of pregnancy than between 32 weeks of pregnancy and 8 weeks postpartum.

Conclusions Symptoms of depression are not more common or severe after childbirth than during pregnancy. Research and clinical efforts need to be moved towards understanding, recognising, and treating antenatal depression.

Introduction

Women are more vulnerable to psychiatric illness during the postnatal period. The rate of psychiatric admission is increased postnatally, mostly because of the raised risk of psychosis in the first month after childbirth.[1] In 1968, Pitt described a syndrome of "atypical depression following childbirth,"[2] although there is now no evidence that there is a categorical difference between depression after childbirth and depression at other times. The prevalence of nonpsychotic depressive illness in the postnatal period is similar to that in the general population.[3 4]

Nevertheless, postnatal depression has become a focus of concern. General practitioners, health visitors, and others are exhorted to recognise and treat this condition. The consequences of postnatal depression to the child, mother, and family may include neglect of the child, family breakdown, self harm, and suicide. However, the more common consequences include emotional and behavioural problems, and cognitive delay in the children of depressed mothers.[5 6]

In contrast, depression during pregnancy has been relatively neglected. Indeed, pregnancy was thought to protect women against depression. Studies of antenatal psychopathology have mostly examined antenatal mood as a predictor of postnatal depression.[7-10] Watson et al found that in 23% of those who had postnatal depression this had started during pregnancy.[11] Depressed mood during pregnancy has also been associated with poor attendance at antenatal clinics, substance misuse, low birth weight, and preterm delivery.[12 13] Psychopathological symptoms during pregnancy have physiological consequences for the fetus, which may explain some of these effects.[14]

We studied mood through pregnancy and after childbirth using prospectively gathered data from a cohort of 14 000 women. We compared depressive symptom score, the pattern of reported symptoms, and the proportion of mothers above a threshold indicating probable…