Drugs commonly given during hospital labor may impair a woman's ability to breastfeed, according to a study conducted by researchers from Swansea University and published in the journal BJOG.

"A lot of women are not given enough information about the medications that might be given to them during childbirth, and women at low risk of bleeding may not need to take these drugs," said Rosemary Dodds of the National (British) Childbirth Trust, who was not involved in the study. "It is important that women understand the risks and can give their informed consent before they go into labor."

Researchers examined data from 45,000 births in South Wales, finding that women who were given either oxytocin (also marketed as pitocin and syntocinon) or ergometrine (also known as ergonovine) were significantly less likely to begin breastfeeding within 48 hours of birth than women who were not given the drugs.

Oxytocin and ergometrine are regularly given to women in order to reduce their risk of postpartum hemorrhaging, even when the risk is already low. Oxytocin is also used in labor in order to stimulate contractions, but this use was not examined in the current study.

Among women who had not been given either drug following the delivery of their child, 65.5 percent began breastfeeding within 48 hours. Among women who had received oxytocin, only 59.1 percent did so, while only 54.6 percent of women who received both drugs began breastfeeding within 2 days.

The researchers suggested that the anti-bleeding drugs could interfere with milk production, thus making breastfeeding more difficult and causing new mothers to give up in frustration.

The study also found that high doses of painkillers known as epidurals also reduce a woman's chance of breastfeeding. Prior studies have also found this connection.

Breastfeeding has been linked to a number of significant lifelong health benefits for both mothers and infants.