Background: Pregnancy in women with intellectual disability (ID) is increasingly recognised, along with their increased likelihood of experiencing risk factors for adverse pregnancy and infant outcomes. Objectives: We aimed to compare risks of socio-demographic, pregnancy and infant outcomes of women with ID to other women. Methods: All mothers with children born in Western Australia from 1983 to 2012 were linked to the population-based Intellectual Disability Exploring Answers database. Mothers with ID were matched by age and Aboriginality to a population sample of mothers without ID. Pregnancy and birth outcomes were compared for both groups and logistic regression was used to compare outcome risks. Results: Compared to non-Aboriginal mothers without ID, non-Aboriginal mothers with ID were more likely to be of low socio-economic status, be without partner, smoke antenatally and have pre-existing asthma. They had a 1.5 times increased risk of pregnancy complications, specifically pre-eclampsia, urinary tract infection, threatened preterm labour and post-partum haemorrhage. After adjustment for maternal medical conditions and pregnancy complications, infants of Aboriginal mothers with ID had twice the risk of preterm birth and 1.6 times the risk of having percentage of optimal head circumference <95% compared to infants of Aboriginal mothers without ID. Infants of both Aboriginal and non-Aboriginal mothers with ID were more likely to have percentage of optimal birth weight <85% compared to those without ID. Conclusions: For mothers with ID, modifiable risk factors for adverse outcomes need addressing. They may require additional assistance during pregnancy, including more frequent consultations and support to assist with pregnancy management.