Background An emerging body of evidence underscores the often-intensive perinatal healthcare needs of women with intellectual and developmental disabilities (IDD). However, population-based research examining postpartum experiences of US women with IDD is sparse. We examined emergency department (ED) use in the postpartum period among Massachusetts mothers with IDD.

Methods We analysed 2002–2010 Massachusetts Pregnancy to Early Life Longitudinal data to compare any and ≥2 ED visits between mothers with and without IDD: within 1–42 days post partum, 1–90 days post partum and 1–365 days post partum. We also determined whether or not such ED use was non-urgent or primary-care sensitive.

Results We identified 776 births in women with IDD and 595 688 births in women without IDD. Across all three postpartum periods, women with IDD were vastly more likely to have any postpartum ED use, to have ≥2 ED visits and to have ED visits for mental health reasons. These findings persisted after controlling for numerous sociodemographic and clinical characteristics. Women with IDD were less likely to have non-urgent ED visits during the three postpartum periods and they were less likely to have primary-care sensitive ED visits during the postpartum period.

Conclusion These findings contribute to the emerging research on perinatal health and healthcare use among women with IDD. Further research examining potential mechanisms behind the observed ED visit use is warranted. High ED use for mental health reasons among women with IDD suggests that their mental health needs are not being adequately met.