, according to a study published online ahead of print Dec. 30, 2019, in JAMA Neurology. The results may explain why previous research failed to find adverse neurodevelopmental effects of breastfeeding in infants whose mothers are undergoing AED treatment, said the authors.
“The results of this study add support to the general safety of breastfeeding by mothers with epilepsy who take AEDs,” wrote Angela K. Birnbaum, PhD, professor of experimental and clinical pharmacology at the University of Minnesota in Minneapolis, and colleagues.
Investigators measured infants’ blood AED concentrations
To date, medical consensus about the safety of breastfeeding while the mother is taking AEDs has been elusive. Researchers have investigated breast milk concentrations of AEDs as surrogate markers of AED concentrations in children. Breast milk concentrations, however, do not account for differences in infant pharmacokinetic processes and thus could misrepresent AED exposure in children through breastfeeding.
Dr. Birnbaum and colleagues sought to measure blood concentrations of AEDs in mothers with epilepsy and the infants that they breastfed to achieve an objective measure of AED exposure through breastfeeding. They examined data collected from December 2012 to October 2016 in the prospective Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs (MONEAD) study. Eligible participants were pregnant women with epilepsy between the ages of 14 and 45 years whose pregnancies had progressed to fewer than 20 weeks’ gestational age and who had IQ scores greater than 70 points. Participants were followed up throughout pregnancy and for 9 months post partum. Children were enrolled at birth.
The investigators collected blood samples from mothers and infants who were breastfed at the same visit, which occurred at between 5 and 20 weeks after birth. The volume of ingested breast milk delivered through graduated feeding bottles each day and the total duration of all daily breastfeeding sessions were recorded. For infants, blood samples were collected from the plantar surface of the heel and stored as dried blood spots on filter paper. The study’s primary endpoint was the percentage of infant-to-mother concentration of AEDs. Concentrations of AEDs in infants at less than the lower limit of quantification were assessed as half of the lower limit.
Exposure in utero may be greater than exposure through breast milk
In all, the researchers enrolled 351 pregnant women with epilepsy into the study and collected data on 345 infants. Two hundred twenty-two (64.3%) of the infants were breastfed, and 146 (42.3%) had AED concentrations available. After excluding outliers and mothers with missing concentration data, Dr. Birnbaum and colleagues included 164 matching infant-mother concentration pairs in their analysis (i.e., of 135 mothers and 138 infants). Approximately 52% of the infants were female, and their median age at blood collection was 13 weeks. The mothers’ median age was 32 years. About 82% of mothers were receiving monotherapy. The investigators found no demographic differences between groups of mothers taking various AEDs.