Evidence exists that the risk factors for depression in the antenatal and postnatal period may differ, but only a handful of studies looked at depression longitudinally. The aims of this study were (1) to estimate the prevalence of postnatal depressive symptoms in Kuwait where data about postnatal depression are scarce and identify its determinants and (2) to compare these risk factors between women who had experienced antenatal depressive symptoms and those that did not. Data collected in the TRansgenerational Assessment of Children’s Environmental Risk (TRACER) Study in Kuwait were used in this analysis. The sample was restricted to the 1348 women who answered the Edinburgh Postnatal Depression Scale (EPDS) both antenatally and postnatally. The prevalence of postnatal depressive symptoms, defined by an EPDS score ≥ 10, was 11.7%. Overall, antenatal depressive symptoms were the strongest determinant of postnatal depressive symptoms. Multivariable logistic regression analysis showed that in women with depressive symptoms in pregnancy, having a lower household income was the most significant risk factor for postnatal depressive symptoms. Among women without antenatal depressive symptoms, those who had lower income, were Kuwaitis, experienced other problems in pregnancy such as perceived stress, PTSD symptoms and social isolation, and those who delivered a boy had higher odds of postnatal depressive symptoms. Antenatal depressive symptoms and other psychosocial characteristics can predict postnatal depressive symptoms. Therefore, maternal mental health issues should be detected during the antenatal period and support should be provided in order to lower the risk of postnatal depression and its sequelae.