Every year 2.4 million HIV positive women worldwide deliver infants. In Canada, increasingly complex highly active antiretroviral therapy (HAART) regimens are widely used by pregnant woman to improve maternal health and reduce transmission to fetuses. However, there are concerns about maternal and fetal complications with HAART. Oak Tree Clinic, British Columbia’s provincial referral centre for maternal-infant care of HIV positive women and their families, maintains a longstanding comprehensive perinatal database. Tessa Chaworth-Musters is investigating, updating and expanding this database to determine complication rates in HAART-exposed pregnancies. Chaworth-Musters is adding new data fields to reflect questions in the current literature, and where available, she is making comparisons to a provincial data set from the BC Reproductive Care Program and using statistical models to determine if specific variables impact outcomes. The findings will guide Oak Tree physicians in their treatment of pregnant HIV positive women and contribute to improvement of provincial and national antiretroviral therapy guidelines and pregnancy practices. Chaworth-Musters also aims to clarify inconsistencies in already published data. Her overall goal is for the research to facilitate understanding of optimal, safe, effective and non-toxic treatment during pregnancy of HIV positive women.