Objective: To study and critically analyze the published evidence on use of metformin for
different indications during pregnancy through a systematic review and to provide background for its
use through a narrative review.
Data sources and Selection of the studies: PubMed, CENTRAL, Embase, SCIENCE DIRECT were
searched up to March 2015. Medical subject handling terms (MeSH) and free text term key words like
metformin, gestational diabetes, metformin in polycystic ovary syndrome (PCOS), metformin in prevention
of gestational diabetes (GDM), metformin in pregnant diabetics were used in combination with Randomised clinical
trial (RCT), metaanalyses and observational studies.
Results: Metformin was used for mainly 4 indications during pregnancy; for glycemic control in gestational and pregestational
diabetes, to prevent GDM and to prevent complications in pregnant patients with PCOS. It was found that metformin
alone or in combination with insulin is effective to achieve glycemic control and is safe to use in pregnancy. In addition,
it is cheap and easy to use with higher patient compliance. It can prevent miscarriage in patients with PCOS but is
not effective in preventing GDM in high risk pregnancies.
Conclusion: In pre-gestational diabetes, use of metformin is encouraging but lacks enough evidence for efficacy as monotherapy.
In GDM, it is safe and effective but the requirement for additional insulin is variable and unpredictable till now.
There is an increasing need for more RCTs to study the clinico-demographic profile of patients in whom metformin is
most likely to be effective as monotherapy. In patients with PCOS, metformin is effective in preventing early pregnancy
loss and improving live birth rate. It was found that use of metformin is not effective in preventing GDM in pregnancy.