Studies have shown that alcohol consumption during pregnancy can alter the brain and behavioral development of unborn offspring. Currently, the Centers for Disease Control and Prevention advises against maternal alcohol use during pregnancy and states that there is no known safe level of consumption. However, what are the consequences of mothers consuming alcohol while breastfeeding?
A research team from the University of California, Riverside conducted a study on mice to find out.
Led by Kelly Huffman, a professor of psychology, the team found that exposure of babies to alcohol through breast milk can have long-lasting effects on their development. Specifically, young mice that were exposed to alcohol during early development show smaller body and brain growth, as well as reduced cortical length, a measure of brain size. The study appears in Frontiers in Neuroscience.
Research shows that approximately 36% of breastfeeding mothers in the United States consume alcohol. In Canada and Australia, the numbers are 20% and 60%, respectively. Women who consume alcohol during pregnancy are more likely to drink while breastfeeding. Additionally, many women who choose to abstain from drinking during pregnancy report that they start drinking again shortly after giving birth.
The researchers focused on lactational ethanol exposure, or LEE, and developed a new model of postnatal alcohol exposure in lactating mice. In this mouse model, pups were exposed to ethanol throughout lactation from postnatal day (P) 6 to P20 (weaning), a period equivalent to infancy in humans.
Compared with controls, LEE mice had reduced body and brain weights, as well as reduced neocortical lengths at weaning and until early puberty (age P30). Brain weight was reduced at both ages for males and at P20 for females; however, P30 female brain weights recovered to control levels. This discovery provides evidence for sex-specific differences due to LEE.
“The reduced body weights in both males and females at P20 and P30 are mirrored in human studies in which infants exposed to ethanol through contaminated breast milk have lower body weights and growth trajectories,” Huffman said. According to her, the reduction in body and brain weight can be explained by the inability of the intestine to extract nutrients efficiently when alcohol is ingested. A decrease in protein synthesis in the small intestine can block the absorption of micro and macronutrients.
Regarding how the behavioral development of LEE mice is affected, Huffman said behavioral tests his team performed on LEE mice suggest that they engage in higher risk behavior and display abnormal stress regulation and increased hyperactivity.
“Therefore, women should refrain from consuming alcohol while breastfeeding until further research can help recommend safe maternal practices in early childhood,” she added.
Although researchers also advocate that women abstain from alcohol during the prenatal period as well, Huffman said there are conflicting views about appropriate and safe drinking behaviors while breastfeeding.
“We are aware of the disconnect between the conclusions drawn from the scientific literature and the behaviors of many new mothers,” she said.
Fetal alcohol exposure, from maternal consumption during pregnancy, has been the subject of research for about 50 years. Huffman’s lab at UCR has made groundbreaking discoveries, including that fetal alcohol spectrum disorders, or FASDs, can be inherited and passed transgenerationally to at least the third generation.
“We hope that our work will increase public awareness of safe motherhood practices,” Huffman said.
Huffman was joined in the study by Roberto F. Pérez Jr., Kathleen E. Conner, Dr. Michael A. Erickson, and Mirembe Nabatanzi.
The research was funded by internal grants from UC Riverside.