Major health care organizations recommend exclusive breastfeeding for six months after birth, but some mothers report stopping due to a perceived lack of milk supply. Penn State College of Medicine researchers found in a recent study that women who stopped breastfeeding because they believed they had insufficient milk supply -; a condition called perceived insufficient milk supply (PIMS) -; are more likely to have a specific mutation in a gene found in breast tissue. These women were also more likely to have babies who gained less weight. The researchers said screening for this mutation, when combined with maternal characteristics such as age and body mass index, could be useful in identifying mothers at risk of stopping breastfeeding early in life. due to a perceived lack of milk production.
The World Health Organization, American Academy of Pediatrics, and American College of Obstetricians and Gynecologists recommend exclusive breastfeeding for at least six months because it provides developing infants with optimal nutrition and is associated with better health outcomes. While 83% of women start breastfeeding, only 57% continue until six months. Socio-economic and environmental factors can contribute to early discontinuation, but milk supply is also an often-cited reason. Identifying women who are more likely to have low milk supply could help them secure resources to continue breastfeeding, such as lactation counseling services.”
Dr. Steven Hicks, Principal Investigator and Pediatrician, Penn State Health Children’s Hospital
Previous research has linked maternal genetics to nutrients in breast milk, but few studies have explored how genetics may relate to supply. The researchers studied 18 genes that are highly expressed in breast or milk-producing tissues in women. They looked for mutations in these genes to see if the mutations were associated with mothers’ perceived milk production.
The study team followed 88 women between the ages of 19 and 42 during the first year of their baby’s life. Mothers responded to surveys about their child’s eating habits at one, four, six and twelve months of age that asked about perceived milk supply, whether women supplemented their child’s diet with formula milk and why they did it. Reduced or low milk supply, signs of breastfeeding allergies, and other personal reasons such as work, day care, or time constraints were included as possible reasons women started to take infant formula. The mothers also provided a DNA sample by having saliva drawn.
Using survey responses, researchers categorized mothers as having either PIMS or perceived adequate milk supply (PAMS). They found that the 45 mothers with PIMS were more likely to breastfeed for shorter periods, report lower milk supply and have infants who were not gaining enough weight.
The researchers analyzed DNA samples from the mothers and looked for mutations in 18 genes involved in the secretion of breast milk. Although changes in 10 of the genes studied were found in some women, the team found that only one, a variant of EGF milk fat globule and V/VIII domain-containing gene (MFGE8), occurred more frequently in women with PIMS. Those without the mutation were more likely to have adequate milk production and report longer breastfeeding duration.
Using statistical modeling, the researchers found that maternal characteristics such as age, duration of previous breastfeeding, and body mass index alone could not differentiate between mothers with PIMS and PAMS. However, when adding MFGE8 mutation status into the model, it strongly predicted which women reported adequate or inadequate milk supplies. The researchers published their findings in the journal Breastfeeding Medicine.
“Identifying the risk of PIMS early in breastfeeding could provide opportunities for early and targeted interventions such as counseling from a trained lactation support professional,” Hicks said. He noted that the current PIMS assessment is guided by subjective reports and that counseling can help identify foods and medications that help or hinder milk production.
Hicks said the study results will need to be validated in a larger study that includes more mothers. He also said more research is needed to uncover the biological processes that determine how this particular gene affects milk production in mothers to better understand its association with PIMS status.
“Moms with this mutation still produce milk, although it may be less than women without the mutation, but challenges like poor diet, hydration or sleep could be enough to hamper the supply they have,” said Hicks said. “Screening for this variant and combining it with reports and maternal characteristics could help identify mothers and babies who may need additional support.”
Penn State College of Medicine
Chandran, D. et al. (2021) Maternal variants of the MFGE8 gene are associated with perceived breast milk supply. Breastfeeding medicine. doi.org/10.1089/bfm.2021.0216.