Health-promoting lifestyle behaviours and their association with antenatal depression and anxiety across pregnancy trimesters in Sri Lanka: a hospital-based cross-sectional study

Background Globally, antenatal depression and anxiety are major contributors to maternal morbidity with disproportionately high prevalence in low- and middle-income countries (LMICs). Despite Sri Lanka’s strong maternal healthcare system, perinatal psychological distress remains under-integrated within routine antenatal services. Health-promoting lifestyle behaviours, conceptualized within Pender’s Health Promotion Model, represent potentially modifiable behavioural factors of maternal mental health. However, trimester-specific evidence from South Asia is limited. This study examined associations between health-promoting lifestyle factors and antenatal depressive and anxiety symptoms among pregnant women in Sri Lanka. Methods A hospital-based cross-sectional study was conducted among 383 pregnant women attending antenatal clinics at two maternity hospitals in Colombo district. Participants completed the Health-Promoting Lifestyle Profile-II (HPLP-II), Edinburgh Postnatal Depression Scale (EPDS), and Perinatal Anxiety Screening Scale (PASS). Pearson correlations assessed bivariate associations. Multiple linear regression models evaluated independent associations controlling trimester and socio-demographic variables. Subgroup analyses explored trimester variation. Results Higher total HPLP-II scores were significantly associated with lower depressive symptoms (β = -0.31, 95% CI -0.42 to -0.20, p < 0.001). Stress management and spiritual growth domains remained independently associated with reduced EPDS scores. Total lifestyle engagement was not significantly associated with overall anxiety scores (p = 0.09). However, physical activity was negatively associated with anxiety symptoms (β = -0.18, p = 0.01), while interpersonal relations (β = 0.16, p = 0.02) and spiritual growth (β = 0.14, p = 0.03) were positively associated. Depressive symptoms were highest during the third trimester, whereas anxiety peaked in the second trimester. Conclusions Health-promoting lifestyle behaviours were significantly associated with reduced antenatal depressive symptoms but demonstrated domain-specific associations with anxiety. Integrating trimester-sensitive behavioural strategies into antenatal care may strengthen maternal mental health outcomes in Sri Lanka and comparable low- and middle-income settings.