Pregnancy, breastfeeding and fertility while taking metformin

Metformin and pregnancy

Metformin is safe to take during pregnancy, either alone or combined with insulin.

Metformin and breastfeeding

If your doctor or midwife says your baby is healthy, you can take metformin while breastfeeding.

Metformin passes into breast milk in tiny amounts and has not been linked with side effects in any breastfed babies.

Metformin would not be expected to cause side effects but contact your health visitor, midwife, pharmacist or doctor as soon as possible if your baby:

• is not feeding as well as usual
• seems unusually sleepy or drowsy
• seems unusually restless or irritable
• looks paler, or is more sweaty, than usual
• seems hungrier than usual
• is peeing more
• is causing you any other concerns

Metformin and fertility

There's no evidence to suggest that taking metformin reduces fertility in either men or women.

Metformin is sometimes prescribed to try to improve ovulation and fertility if you have polycystic ovary syndrome (PCOS).

Having a healthy body weight is important both for fertility and for pregnancy. Your doctor may suggest losing weight in the first instance if you have PCOS. This is also likely to improve ovulation and help both you and your baby during pregnancy.

Find out more about how metformin can affect you and your baby during pregnancy on the Best Use of Medicines in Pregnancy (BUMPS) website.