Does Fetal Growth Adequacy Affect the Nutritional Composition of Mothers' Milk?: A Historical Cohort Study

Abstract

Objective The study aimed to assess the association between intrauterine growth of preterm infants and energy and macronutrient contents in their mothers' milk. Study Design A historical cohort of mothers of preterm infants was assessed according to offspring's intrauterine growth. Fetal growth restriction (FGR) was defined as small-for-gestational age or appropriate for gestational age with fetal growth deceleration. During the first 4 weeks after delivery, the composition of daily pool samples of mothers' milk was measured by using a mid-infrared human milk analyzer. Explanatory models for milk energy, true protein, total carbohydrate, and fat contents were obtained by generalized additive mixed effects regression models. Results In total, 127 milk samples were analyzed from 73 mothers who delivered 92 neonates. Energy content was significantly higher in mothers with chronic hypertension (average: +6.28 kcal/dL; 95% confidence interval [CI]: 0.54–12.01; p = 0.034) and for extremely preterm compared with very preterm infants (average: +5.95 kcal/dL; 95% CI: 2.16–9.73; p = 0.003), and weakly associated with single pregnancies (average: +3.38 kcal/dL; 95% CI: 0.07–6.83; p = 0.057). True protein content was significantly higher in mothers with chronic hypertension (average: +0.91 g/dL; 95% CI: 0.63–1.19; p < 0.001) and with hypertension induced by pregnancy (average: +0.25 g/dL, 95% CI: 0.07–0.44; p = 0.007), and for extremely preterm compared with very and moderate preterm infants (average: +0.19; 95% CI: 0.01–0.38; p = 0.043 and +0.28 g/dL; 95% CI: 0.05–0.51; p = 0.017, respectively). Fat content was weakly and negatively associated with FGR, both in SGA infants and AGA infants with fetal growth deceleration (average: −0.44 g/dL; 95% CI: −0.92 to −0.05; p = 0.079 and average: −0.36 g/dL; 95% CI: −0.74 to −0.02; p = 0.066, respectively). Conclusion Energy and macronutrient contents in mothers' milk of preterm infants was significantly and positively associated with the degree of prematurity and hypertension. The hypothesis that the composition of milk is associated with FGR was not demonstrated. Key Points

Influence of maternal and perinatal factors on macronutrient content of very preterm human milk during the first weeks after birth

“…The relationship between suboptimal fetal growth and human milk macronutrients is controversial, likely due to heterogeneity in definition of IUGR and in the gestational age of target populations. The aforementioned study by Correia et al described a negative association of IUGR with fat but not protein content during the first weeks, which is in disagreement to our findings [45]. This may be due to differences in other characteristics (maternal BMI, breastfeeding history) that we have found to have an association and were not included in their analysis.…”

“…Pregnancy complications. In agreement with our results, a lower earlier fat content and a higher protein density after the first few weeks following preterm birth in mothers with a history of preeclampsia [45] have been reported. The relationship between suboptimal fetal growth and human milk macronutrients is controversial, likely due to heterogeneity in definition of IUGR and in the gestational age of target populations.…”

Sex Related Nutritional Outcomes Among Preterm Very Low Birth Weight Infants

“…7,8 Furthermore, evidence suggests the effect of diet enhancement on growth and neurodevelopment may be sex-dependent, with increased bene ts seen in male infants. 6,8 The higher macronutrient content in human milk produced by mothers of male infants, as well as their production of more signi cant volumes of milk, 9 further suggests nutritional requirements may differ depending upon infant sex 10,11 Yet sex-speci c nutritional support is rarely addressed when caring for preterm VLBW infants in the NICU. Furthermore, although sex-speci c differences exist regarding morbidity, mortality, and growth, little is known regarding potential differences in other nutritional outcomes in infants born preterm and VLBW.…”