About one-third of South African women have clinically significant symptoms of postpartum depression (PPD). Several socio-demographic risk factors for PPD exist, but data on medical and obstetric risk factors remain scarce for low- and middle-income countries and particularly in sub-Saharan Africa. We aimed to estimate the proportion of women with PPD and investigate socio-demographic, medical and obstetric risk factors for PPD among women receiving private medical care in South Africa (SA).

In this longitudinal cohort study, we analysed reimbursement claims from beneficiaries of an SA medical insurance scheme who delivered a child between 2011 and 2020. PPD was defined as a new International Classification of Diseases, 10th Revision diagnosis of depression within 365 days postpartum. We estimated the frequency of women with a diagnosis of PPD. We explored several medical and obstetric risk factors for PPD, including pre-existing conditions, such as HIV and polycystic ovary syndrome, and conditions diagnosed during pregnancy and labour, such as gestational diabetes, pre-term delivery and postpartum haemorrhage. Using a multivariable modified Poisson model, we estimated adjusted risk ratios (aRRs) and 95% confidence intervals (CIs) for factors associated with PPD.

Of the 47,697 participants, 2,380 (5.0%) were diagnosed with PPD. The cumulative incidence of PPD increased from 0.8% (95% CI 0.7–0.9) at 6 weeks to 5.5% (5.3–5.7) at 12 months postpartum. PPD risk was higher in individuals with history of depression (aRR 3.47, 95% CI [3.14–3.85]), preterm delivery (1.47 [1.30–1.66]), PCOS (1.37 [1.09–1.72]), hyperemesis gravidarum (1.32 [1.11–1.57]), gestational hypertension (1.30 [1.03–1.66]) and postpartum haemorrhage (1.29 [0.91–1.85]). Endometriosis, HIV, gestational diabetes, foetal stress, perineal laceration, elective or emergency C-section and preeclampsia were not associated with a higher risk of PPD.

The PPD diagnosis rate was lower than anticipated, based on the PPD prevalence of previous studies, indicating a potential diagnostic gap in SA’s private sector. Identified risk factors could inform targeted PPD screening strategies.

Untreated maternal depression during the postpartum period can have a profound impact on the short- and long-term psychological and physical well-being of children. There is, therefore, an imperative for increased understanding of the determinants of depression and depression-related healthcare access during this period.

Respondents were 11 089 mothers of 9-month-old infants recruited to the Growing Up in Ireland study. Of this sample, 10 827 had complete data on all relevant variables. Respondents provided sociodemographic, socioeconomic and household information, and completed the Center for Epidemiologic Studies Depression Scale (CESD).

11.1% of mothers scored above the CESD threshold for depression. 10.0% of depressed mothers and 25.4% of depressed fathers had depressed partners. Among depressed mothers, 73.1% had not attended a healthcare professional for a mental health problem since the birth of the cohort infant. In the adjusted model, the likelihood of depression was highest in mothers who: had lower educational levels (odds ratio (OR) 1.26; 95% confidence intervals (CIs) 1.08, 1.46); were unemployed (OR 1.27; 95% CIs 1.10, 1.47); reported previous mental health problems (OR 6.55; 95% CIs 5.68, 7.56); reported that the cohort child was the result of an unintended pregnancy (OR 1.43; 95% CIs 1.22, 1.68), was preterm (OR 1.35; 95% CIs 1.07, 1.70), or had health/developmental problems (OR 1.20; 95% CIs 1.04, 1.39); had no partner in the household (OR 1.33; 95% CIs 1.04, 1.70) or were living with a depressed partner (OR 2.66; 95% CIs 1.97, 3.60); reported no family living nearby (OR 1.33; 95% CIs 1.16, 1.54); were in the lowest income group (OR 1.60; 95% CIs 1.21, 2.12). The primary determinant of not seeking treatment for depression was being of non-white ethnicity (OR 2.21; 95% CIs 1.18, 4.13).

Results highlight the prevalence of maternal depression in the later postpartum period, particularly for lower socioeconomic groups, those with previous mental health problems, and those with limited social support. The large proportion of unmet need in depressed mothers, particularly among ethnic minority groups, emphasises the need for a greater awareness of postpartum mental health problems and increased efforts by healthcare professionals to ensure that mothers can access the required services.