Secretory IgA in Colostrum and Neonatal Feces is Not Associated With Maternal Nutrient Intake in Newborns From Healthy Mothers.

Background: Human milk shapes neonatal immunity through antibodies, transferring passive immunity to the infant, mainly by secretory IgA (sIgA). sIgA provides antimicrobial defense in the infant's gastrointestinal tract, protecting the newborn against infections and mediating much of the potential of human milk to decrease disease risk. Although maternal nutrition may influence some human milk characteristics, the influence of specific maternal macro and micronutrient intake on sIgA concentrations in colostrum is unknown.

Research aim: To evaluate the association of maternal nutrient intake with sIgA in colostrum and neonatal feces of full-term newborns from healthy mothers.

Method: We used a cross-sectional design to study the colostrum of healthy mothers with uncomplicated pregnancies (N = 17) and the neonatal feces of their term infants. Maternal intake at term was assessed, and the concentration of sIgA was measured by ELISA.

Results: The mean (SD) concentration of sIgA in colostrum was 3.42 (6.0) mg/ml, and 8.5 (1.93) mg/g in neonatal feces. The concentration of sIgA in colostrum did not correlate with fecal sIgA concentrations (r = -0.166 p = 0.606). sIgA concentrations in colostrum or feces were similar by sex and delivery method (p = 0.880 and p = 0.0946 respectively). Maternal macro and micronutrient intake was not associated with colostrum or fecal sIgA. Concentrations of sIgA in colostrum and feces were not correlated with maternal age, pregestational BMI, or gestational weight gain. Also, no correlations between colostrum sIgA concentrations and neonatal anthropometry were found. Interestingly, fecal sIgA was negatively associated with birth weight (R² = 0.433, p = 0.032), independent of gestational age.

Conclusions: These results suggest that colostrum maintains its immunological properties, independently of maternal nutritional intake at term, and that the presence of sIgA in the newborn's intestine may be related to the newborn's weight. These findings can encourage women to establish lactation as early as possible and continue with it, confident that their dietary habits prior to birth do not affect their colostrum's immune potential.