MPA given orally during the first trimester for threatened miscarriage carries no specific risk for foetal abnormalities albeit the rate is higher than non-threatened pregnancies

This observational study examines the outcomes of pregnancies arising in women referred for infertility, where those who experienced threatened miscarriage were treated with medroxyprogesterone acetate (MPA) tablets. The 14-year study period covers comprehensive real-time data entries into the validated electronic database including details of the infertility management, pregnancy outcomes and any foetal anomalies among the infants, each being tracked and recorded. Of 4057 clinical pregnancies, 1343 received MPA for threatened miscarriage; 934 (69.6 %) of which continued to livebirths. These were compared with the remaining 2714 clinical pregnancies without threatened miscarriage or MPA and which resulted in 2075 (76.5 %) livebirths. There were 134 developmental abnormalities recorded among the 3009 livebirths of which 78 (2.6 %) were categorised appropriate for the Western Australian Developmental Abnormalities Register; WARDA. These comprised 55 in the MPA group, 36 of which were categorised as serious (being 2.7 % of clinical pregnancies and 3.9 % of births). In the group without MPA, there were 79 abnormalities, of which 42 were categorised as serious (being 1.7 % of clinical pregnancies and 2.2 % of births). Specifically, there were no cases of androgenisation noted among the female infants. The abnormality rates were low overall and well within the annual WARDA ranges. We cautiously suggest that oral MPA can be considered for studies throughout pregnancy including the early first trimester to assess a potential role in reducing miscarriage, as well as advanced pregnancies to evaluate a potential role in reducing stillbirths and preterm delivery.