BackgroundWhile discrimination takes multiple forms, racial or ethnic discrimination is a root cause of this health-damaging social phenomenon. We drew on intersectionality theory, which offers an account of discrimination’s multiple effects, to consider associations between women’s experiences of discrimination and postpartum depression (PPD) using four measures: single forms of discrimination (SFD); multiple forms of discrimination (MFD); ethnic discrimination combined with MFD (E-MFD); and a composite MFD that interacted with women’s identity (C-MFD).MethodsWe interviewed a stratified sample of 1128 mothers face to face in 2014–2015 during mothers’ visits to maternal and child health clinics. The mothers belonged to three groups in Israel: Palestinian-Arab minority, Jewish immigrant, and non-immigrant Jewish. We conducted unadjusted and adjusted logistic regressions for PPD, measured on the Edinburgh Postnatal Depression Scale, in associations with SFD (experiencing discrimination based on any of the following: age, sex, class, ethno-national identity, religiosity level and skin color); MFD (experiencing 0,1, 2 or ≥ 3 of SFD); E-MFD (ethnic discrimination combined with other MFD); and finally, C-MFD (interaction between MFD and women’s identity).ResultsPalestinian-Arab mothers had higher PPD and reported higher SFD (based on ethnicity, religiosity level, and socioeconomic status), as well as higher MFD and E-MFD. This was followed by Jewish immigrant mothers, and lastly by non-immigrant Jewish mothers. However, both MFD and E-MFD had a strong association with PPD among non-immigrant Jewish mothers reporting 2MFD and ≥ 3MFD, and Palestinian-Arab mothers reporting ≥3MFD, but no significant association among immigrant Jewish mothers. When we used C-MFD, we found a dose-response association in which Palestinian-Arab mothers experiencing more MFD (2MFD and ≥ 3MFD) were more likely to experience PPD. This was followed by immigrant Jewish mothers (reporting 2MFD and ≥ 3MFD), and lastly by non-immigrant Jewish mothers.ConclusionsMFD should be considered in relation to women’s identity (being part of a minority, immigrant, or non-immigrant majority group) in maternal mental health research and practice. Otherwise, we risk underestimating the effects of MFD on PPD, especially in minority and immigrant mothers, who are more likely to face interlocking forms of discrimination.