Newborns Fed Breast Milk Exclusively in Hospital Had Lower Asthma Risk

ORLANDO — Infants who exclusively received breast milk throughout their birth hospitalization were less likely to be diagnosed with asthma in early childhood, a database analysis suggested.

Among nearly 10,000 children, bivariate analysis showed that exclusive human milk or mother’s milk was associated with a 41% lower odds of asthma in early childhood (P<0.001 for both), Laura Ward, MD, of Cincinnati Children's Hospital Medical Center, reported here.

Looking just at the children born full-term, and adjusting for other factors associated with asthma, showed that “infants who were exclusively fed breast milk throughout the birth hospitalization were 22% less likely to have a diagnosis of childhood asthma,” she said at the American Academy of Pediatrics (AAP) annual meeting.

Breastfeeding has been associated with a reduced risk of childhood illness, including asthma, with longer duration of exclusivity linked to greater benefit. AAP recommends exclusive breastfeeding for about 6 months, with possible continuation for 2 years or longer.

Though the postpartum hospital stay is typically just a few days long, it represents an important period for developing a successful breastfeeding trajectory, Ward said.

Since it is known that breastfeeding offers certain protections to both mothers and babies, “we thought it might be interesting to see if there was a relationship between early breastfeeding during the birth hospitalization to these longer-term childhood outcomes like asthma,” Ward said.

Researchers tapped into the Maternal Infant Data Hub, a regional perinatal database of maternal and infant dyads, and linked them with infants born at Cincinnati Children’s Hospital Medical Center from 2017 to 2019. Feeding data — such as type, frequency, and timing — were obtained from birth hospitalization data, while asthma diagnoses were collected from children’s hospital records.

The study population included 9,649 kids, of whom 51% were boys, 45% were white, 35% were Black, and 60% were on public health insurance. Most (84.4%) were born full-term (≥37 weeks), while 11.1% were born at 32-36 weeks’ gestational age and 4.5% before 32 weeks.

Of those, 480 kids (5%) had asthma. This group included a higher proportion of boys (60%), Black children (54%), and a greater percentage covered by public insurance (71%). The proportion of kids born preterm was also higher in this group: 14.6% born at 32-36 weeks’ gestational age and 11.7% before 32 weeks.

Overall, 81% of the infants received some breast milk during their birth hospitalization, with 31% receiving breast milk exclusively.

Bivariate analysis of the entire population showed that infants had the lowest odds of asthma if they received human milk exclusively (OR 0.59, 95% CI 0.47-0.85, P<0.001) or mother's milk exclusively (OR 0.59, 95% CI 0.46-0.74, P<0.001). Odds of asthma were also lower for those whose first feeding or feeding at discharge (the 24-hour period leading up to discharge) was breast milk.

Of the subset born full-term, multivariate analysis — which adjusted for sex, race, and insurance type — showed lower odds of asthma for infants who received mother’s milk exclusively (OR 0.78, 95% CI 0.60-1.00, P=0.049), those who had human milk exclusively at discharge (OR 0.76, 95% CI 0.60-0.97, P=0.026), and those who had mother’s milk exclusively at discharge (OR 0.77, 95% CI 0.60-0.97, P=0.027).

Though external factors may contribute to the development of asthma, the current research “highlights the importance of early breastfeeding, especially exclusive breastfeeding,” in this area, Ward said.

Future work is needed to study additional variables, such as prenatal, postnatal, and environmental factors, that may influence asthma outcomes, according to the researchers.