A growing number of babies born in the U.S. are breastfed, and health officials are pushing to make it easier for even more new mothers to nurse their babies. But experts say there still isn’t enough research about one of the most common experiences among lactating women: taking medication.
Scientific studies frequently exclude pregnant and lactating women, which means there’s little information about whether drugs are safe to use while pregnant or breastfeeding, how well they work, or the best doses to take. And in a new perspective paper published Wednesday in the New England Journal of Medicine, OB-GYNs say there is still a slew of unanswered questions about drug use while breastfeeding.
“There’s limited information in pregnancy. When you move to lactation, there’s even fewer studies,” said Dr. Catherine Spong, a co-author of the paper and an OB-GYN at the University of Texas Southwestern Medical Center.
More than half of women worldwide take one or more medications in the months after they give birth, but the information to guide their treatment is limited. Much of the research available is pulled together in a federal database called LactMed, which experts say has been an important tool in providing patients and providers with information on medication use during lactation. But the paper’s authors say LactMed’s data is “limited at best.” Of the 1,408 products in the database as of November 2018, just 2 percent had recommendations that were based on strong, lactation-specific data.
Information about medication use while breastfeeding is similarly scarce on drug labels. When the FDA analyzed 575 prescription medications and biologic products that had labels approved between 2015 and 2017, the agency found that only 15 percent included data on human lactation. Drug makers had run post-marketing studies looking at lactation on just 11 of those products, which, all told, enrolled only 27 women.
That’s left women and their health care providers to guess whether a medication is safe and effective while breastfeeding.
“It’s not really given any significant attention. Women have to just figure it out all by themselves,” said Diane Spatz, director of the lactation program at Children’s Hospital of Philadelphia and a nurse researcher who studies breastfeeding. In some cases, providers said, that means women who need to take a medication stop breastfeeding out of an abundance of caution.
Another area where research is scarce: how to adjust drug doses to account for biological changes while a woman is lactating. Because the body changes dramatically after pregnancy and while breastfeeding, standard doses of drugs might not work well for lactating women.
“If we don’t study how these drugs are metabolized or excreted [in lactating women], we don’t have the information available about how best to dose them,” said Spong, who previously served as the chair of the federal task force.
That lack of information also means clinicians and researchers don’t know as much as they’d like to about the possible effects that medications in breast milk might have on a baby. Experts say there’s a need to study not only whether medications in breast milk can impact a baby, but also how much of a given medication turns up in breast milk and how the concentration changes over time.
“There’s a clear need for a research agenda in this area,” said Dr. Diana Bianchi, the director of the National Institute of Child Health and Human Development. Bianchi also serves as the chair of a federal task force on research involving pregnant and lactating women, which was established in 2016 and recently renewed for another two years of work. In September, the task force submitted 15 recommendations to the Department of Health and Human Services, including pushing drug companies and researchers to include pregnant women and nursing mothers in their studies, unless there’s a good scientific reason to exclude them.
“It’s important to change the culture and thinking to protecting women through research, not from research,” Bianchi said.
The new paper lays out several ways to improve research on lactating women specifically, starting with including them in Phase 1 and Phase 2 clinical trials to get more information about dosing and efficacy. Experts said it’s also important to collect data from breastfeeding women who are taking already approved drugs to get a better understanding of dosing, efficacy, and safety. Another idea: Researchers could run studies with small groups of lactating women on how drugs are metabolized and excreted through breast milk.
More research will require more funding. In 2017, the NIH spent $92 million on research related to breastfeeding, lactation, or breast milk — compared to nearly $6 billion on cancer research and $1.1 billion on diabetes studies, the authors of the paper note. A funding boost might also lure more scientists to study lactation, which hasn’t garnered widespread interest among researchers, Spatz said.
“Because there’s so few research dollars,” she said, “there’s so few of us who are scientists in this field.”