A critical appraisal of controlled studies investigating malformation risks following pregabalin use in early pregnancy.

In March 2022, the Summary of Product Characteristics for the Lyrica brand of pregabalin was updated with warnings regarding malformation risks. This literature review and critical appraisal aims to explore whether these Summary of Product Characteristics updates are justified and provide clarity on the risk-benefit balance for pregabalin use in early pregnancy. A literature review was conducted in May 2022 to identify English language comparative studies of any design providing data about first trimester maternal pregabalin use and malformation risk. Five observational comparative cohort studies using data from 9 distinct datasets were located. Collectively these studies described at least 5300 unique pregabalin exposed pregnancies, with 4900 exposed in at least the first trimester. Three studies investigated overall major malformation risks, and 4 investigated specific malformation risks. The available evidence was found to be conflicting and generally of low quality, probably influenced by bias and data confounding, with no clear pattern of specific malformations observed. Findings from the largest study suggested absolute risks of major malformation of 4.8-5.6%, relative to a background risk of approximately 4%. Due to study methodology limitations, the available data were judged to only provide low quality evidence suggestive of a possible and unconfirmed small increased risk that cannot be solely attributed to foetal pregabalin exposure. This literature review and critical appraisal indicates that the Lyrica product literature updates are insufficiently substantiated and could result in confusion and misinformed clinical risk-benefit decision making.