Introduction
This paper explores a range of perinatal risk factors that may increase maternal vulnerability to postnatal psychological distress in a sample of 17 531 women participating in the Millennium Cohort Study, a diverse British, longitudinal birth cohort study.

Material and methods
Using a graphical network modeling framework, this study models the links between postnatal psychological distress and perinatal risk factors, while controlling for sociodemographic factors and history of depression and anxiety. Postnatal psychological distress was assessed at 9 months postpartum using the Rutter Malaise Inventory.

Results
Results of the graphical network models indicate that lower levels of happiness about the pregnancy (Edge weight [w] = 0.084, 95% CI = 0.069‐0.100, b = 0.095), smoking during pregnancy (w = 0.026, 95% CI = −0.009‐0.060, b = 0.029), infection during pregnancy (w = 0.071, 95% CI = 0.024‐0.118, b = 0.090), hyperemesis gravidarum (w = 0.068, 95% CI = 0.013‐0.123, b = 0.083), baby in special care (w = 0.048, 95% CI = −0.004‐0.099, b = 0.062), not being white (w = 0.101, 95% CI = 0.062‐0.140, b = 0.118), being from a more deprived area (w = −0.028, 95% CI = −0.051 to −0.005, b = −0.039), lower income (w = −0.025, 95% CI = −0.055‐0.005, b = −0.036), and history of depression or anxiety (w = 0.574, 95% CI = 0.545‐0.603, b = 0.764) were associated with increased psychological distress.

Conclusions
Some perinatal risk factors may be directly associated with postnatal psychological distress, but many risk factors appear to be primarily associated with demographic factors. This emphasizes the importance of taking a holistic approach when evaluating an individual's risk of developing postnatal psychological distress.