There is limited data on the safety of drugs during pregnancy and lactation. In part, because researchers, for ethical reasons, have been reluctant to study mother-infant pairs.

In an effort to expand the knowledge base, the Food and Drug Administration’s Pediatric Advisory Committee (PAC) recommends that, in the future, infant blood sampling be the gold standard for all clinical research trials involving lactating mothers.

While there was majority consensus without formal vote, the PAC clearly stated that the need for knowledge must always be balanced against the necessity to protect breastfeeding infants from receiving, through their mother’s milk, medicines they would not otherwise be exposed to.

According to Chairwoman Marsha Rappley, the issue that generated the most disagreement among committee members was whether clinical lactation studies should only enroll mother-infant pairs who are exclusively breastfeeding. The majority view was that mother-infant pairs who reflect the general practice in the community should be studied, including mothers who use both breastfeeding and supplements and those who rely solely on breastfeeding.

The advisory committee did not want to state categorically that any specific period of time should not be studied during clinical lactation studies, which would happen, for instance, if enrollment were restricted to mother-infant pairs in whom breastfeeding was well-established or if a minimum number of weeks postpartum were set before which mother-infant pairs could not be enrolled. Instead, patient enrollment “should depend on a risk-benefit analysis of the study for both the mother and the infant,” Rappley said.