A rise in breastfeeding comes at expense of mothers’ careers, a study finds.

Breast is best, according to the campaign launched by the World Health Organization and the Centers for Disease Control and Prevention. But regulations encouraging breastfeeding may come at a steep price, according to the new research.

The study finds that state hospital regulations aimed to encourage breastfeeding, such as requiring a lactation consultant on staff, increased the likelihood that new mothers would start breastfeeding by almost 4%.

The regulations also increased the probability that the women continued breastfeeding through the first year of their children’s lives by as much as 7%.

However, mothers who chose to breastfeed significantly increased their time spent on child care, leading many to reduce their work hours, reduce their positions to part time, or leave the workforce entirely. And that may cause substantially lower wages and earnings down the line.

“These types of policies enable women who would like to breastfeed who previously did not have sufficient support or information to be able to do that,” says Emily Lawler, coauthor of the study and an assistant professor in the University of Georgia’s School of Public and International Affairs. “The bigger picture is that the US has really focused on pushing breastfeeding as a goal, but we have done that without thinking through all of the relative costs of that decision.”

One of the biggest costs of breastfeeding, the study found, is loss of time.

During the first few days after birth, babies can eat as often as every hour, according to the CDC. As they get older, they still require eight to 12 feedings in a 24-hour period over the first six months of their lives.

And many breastfeeding organizations suggest women who begin pumping breast milk should do so every couple of hours. On average, pumping takes 15 to 20 minutes, not including the time spent bottling milk and cleaning the machine’s parts after each session.

The researchers found women with infants reduced their labor force participation by up to 3%.

Read the full article about the cost of breastfeeding by Leigh Beeson at Futurity.