Human milk pH is associated with fortification, postpartum day, and maternal dietary intake in preterm mother-infant dyads

Objective To compare pH of human milk types (mother’s own milk (MOM), pasteurized donor human milk (PDHM), fortified MOM, and fortified PDHM) fed to preterm infants. Study design This observational study consisted of 63 mother-infant dyads < 34 weeks gestation. Human milk samples ( n = 245), along with maternal factors, were collected for pH analysis. pH of MOM was analyzed over the course of lactation accounting for fortification status, postpartum day, and storage conditions. Results Mean pH of MOM was slightly acidic at 6.60 ± 0.28, which was significantly higher ( p < 0.05) than other milk types. pH of MOM varied by fortification, postpartum day, and maternal vegetable/fiber intake. There was a significant interaction between fortification status and postpartum day; pH of MOM decreased over time, while pH of fortified MOM increased over time. Conclusion pH of human milk varied by type. pH of MOM was significantly associated with fortification status, postpartum day, and maternal vegetable/fiber intake.