Pre-pregnancy body mass index and the risk of antenatal depression and anxiety

Background: While the physical health risks of obesity during pregnancy for women are well understood, little is known about the mental health implications. The aim of this study was to investigate the relationship between pre-pregnancy body mass index (BMI) and symptoms of antenatal depression and anxiety. 

Methods: Secondary analysis of cross-sectional data contributed by the younger cohort (born 1973–78) of the Australian Longitudinal Study of Women's Health who were pregnant at the time of the survey (Waves 4–6: aged 28–39 years). Primary outcomes were symptoms of depression (Center for Epidemiologic Studies Depression Scale 10 score ≥ 10) and anxiety (Goldberg Anxiety Scale score ≥ 6). BMI was assessed using self-reported pre-pregnancy weight and height. Demographic characteristics, psychosocial factors, health behaviors and reproductive history were assessed using study-specific and standardized measures. Multivariable regression models were used to examine the associations between predictors and outcome scores. 

Results: The mean pre-pregnancy BMI of the 1621 women included in the analysis was 24.9 kg/m²; more than a third (39.8%) were overweight or obese. More than one in ten (15.4%) had depressive symptoms, and a quarter (25.0%) had anxiety symptoms. Higher pre-pregnancy BMI and certain sociodemographic characteristics including not having a paid job were significantly related to higher antenatal depression and anxiety scores. 

Conclusions: High pre-pregnancy BMI is significantly associated with an increased risk of antenatal depression and anxiety. Consistent with clinical practice guidelines, women with high pre-pregnancy BMI should be screened and assessed for depression and anxiety, and where appropriate provided with clinical referral pathways and support.