Q: Is Metformin a problem during pregnancy?

A: Hyperinsulinism (too much insulin) has been implicated as a mediator of ovulatory disturbance in women with polycystic ovarian syndrome (PCOS). Metformin has been reported to restore ovulatory function and it has been suggested that continuing metformin during the first trimester can decrease the incidence of spontaneous abortion associated with PCOS. This suggestion was based on two spontaneous abortions among 19 treated women, compared with 16 spontaneous abortions among 22 PCOS pregnancies not treated with metformin. There were no congenital anomalies among 11 infants born at the time of the report. Another report found that among 33 women with PCOS who were maintained on metformin during pregnancy, the incidence of gestational diabetes was 3% compared with an incidence of 31% in PCOS pregnancies without metformin. All 34 of the babies born to the 33 women treated with metformin were said to be normal, although details of the method of evaluation of the children were not given.

Langer O, Conway D, Berkus M, Xenakis EM: There is no association between oral hypoglycemic use and fetal anomalies. Am J Obstet Gynecol 1999;180:S38. Glueck CJ, Phillips H, Cameron D, Sieve-Smith L, Wang P. Continuing metformin throughout pregnancy in women with polycystic ovary syndrome appears to safely reduce first-trimester spontaneous abortion: a pilot study. Fertil Steril 2001;75:46-52. Glueck CJ, Wang P, Kobayashi s, Phillips H, Sieve-Smith L. Metformin therapy throughout pregnancy reduces the development of gestational diabetes in women with polycystic ovary syndrome. Fertil Steril 2002;77:520-5.