BackgroundMaternal weight variables are important predictors of postpartum depression (PPD). While preliminary evidence points to an association between pre-pregnancy obesity and PPD, the role of excessive gestational weight gain (GWG) on PPD is less studied. In this secondary cohort analysis of the German ‘healthy living in pregnancy’ (GeliS) trial, we aimed to investigate associations between weight-related variables and PPD and to assess the influence of GWG on the risk for PPD.MethodsWe included women with normal weight, overweight, and obesity (BMI 18.5–40.0 kg/m2). Symptoms of PPD were assessed 6–8 weeks postpartum using the Edinburgh Postnatal Depression Scale. Pre-pregnancy BMI was self-reported. During the course of pregnancy, weight was measured at gynaecological practices within regular check-ups. GWG was defined as the difference between the last measured weight before delivery and the first measured weight at the time of recruitment (≤ 12th week of gestation). Excessive GWG was classified according to the Institute of Medicine. Multiple logistic regression analyses were used to estimate the odds of PPD in relation to pre-pregnancy BMI, GWG, and excessive GWG adjusting for important confounders.ResultsOf the total 1583 participants, 45.6% (n = 722) showed excessive GWG and 7.9% (n = 138) experienced PPD. Pre-pregnancy BMI (per 5-unit increase; OR = 1.23, 95% CI 1.08–1.41, p = 0.002) and pre-pregnancy overweight or obesity were significantly positively associated with the odds of developing PPD, particularly among women with an antenatal history of anxiety or depressive symptoms (overweight: OR = 1.93, 95% CI = 1.15–3.22, p = 0.01; obesity: OR = 2.11, 95% CI = 1.13–3.96, p = 0.02). Sociodemographic or lifestyle factors did not additively influence the odds of having PPD. In fully adjusted models, there was no significant evidence that GWG or the occurrence of excessive GWG increased the odds of experiencing PPD (excessive vs. non-excessive: OR = 3.48, 95% CI 0.35–34.94; GWG per 1 kg increase: OR = 1.16, 95% CI 0.94–1.44).ConclusionPre-pregnancy overweight or obesity is associated with PPD independent of concurrent risk factors. History of anxiety or depressive symptoms suggests a stress-induced link between pre-pregnancy weight and PPD.Trial registrationNCT01958307, ClinicalTrials.gov, retrospectively registered on 9 October 2013.