Major malformations risk following early pregnancy exposure to metformin: a systematic review and meta-analysis.

Abolhassani, Nazanin; Winterfeld, Ursula; Kaplan, Yusuf C; Jaques, Cécile; Minder Wyssmann, Beatrice; Del Giovane, Cinzia; Panchaud, Alice (2023). Major malformations risk following early pregnancy exposure to metformin: a systematic review and meta-analysis. BMJ open diabetes research & care, 11(1), e00291. BMJ Publishing Group 10.1136/bmjdrc-2022-002919

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Metformin is considered as first-line treatment for type 2 diabetes and an effective treatment for polycystic ovary syndrome (PCOS). However, evidence regarding its safety in pregnancy is limited. We conducted a systematic review and meta-analysis of major congenital malformations (MCMs) risk after first-trimester exposure to metformin in women with PCOS and pregestational diabetes mellitus (PGDM). Randomized controlled trials (RCTs) and observational cohort studies with a control group investigating risk of MCM after first-trimester pregnancy exposure to metformin were searched until December 2021. ORs and 95% CIs were calculated separately according to indications and study type using Mantel-Haenszel method; outcome data were combined using random-effects model. Eleven studies (two RCTs; nine observational cohorts) met the inclusion criteria: four included pregnant women with PCOS, four included those with PGDM and three evaluated both indications separately and were considered in both indication groups. In PCOS group, there were two RCTs (57 exposed, 52 control infants) and five observational studies (472 exposed, 1892 control infants); point estimates for MCM rates in RCTs and observational studies were OR 0.93 (95% CI 0.09 to 9.21) (I2=0%; Q test=0.31; p value=0.58) and OR 1.35 (95% CI 0.37 to 4.90) (I2=65%; Q test=9.43; p value=0.05), respectively. In PGDM group, all seven studies were observational (1122 exposed, 1851 control infants); the point estimate for MCM rates was OR 1.05 (95% CI 0.50 to 2.18) (I2=59%; Q test=16.34; p value=0.01). Metformin use in first-trimester pregnancy in women with PCOS or PGDM do not meaningfully increase the MCM risk overall. However, further studies are needed to characterize residual safety concerns.

Item Type:

Journal Article (Original Article)


13 Central Units > Administrative Director's Office > University Library of Bern
04 Faculty of Medicine > Medical Education > Institute of General Practice and Primary Care (BIHAM)

UniBE Contributor:

Abolhassani, Nazanin, Minder, Beatrice, Del Giovane, Cinzia, Panchaud Monnat, Alice Elke Martine


000 Computer science, knowledge & systems > 020 Library & information sciences
600 Technology > 610 Medicine & health
300 Social sciences, sociology & anthropology > 360 Social problems & social services




BMJ Publishing Group




Pubmed Import

Date Deposited:

01 Feb 2023 10:21

Last Modified:

09 Feb 2023 19:25

Publisher DOI:


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Uncontrolled Keywords:

Metformin Polycystic Ovary Syndrome Pregnancy Type 2 Diabetes




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