Abstract
We read with great interest article by Wu et al. “The concentration of lactoferrin in breast milk correlates with maternal body mass index and parity”. 1 Lactoferrin (LF) is essentially one of the most important protective factors promoting and protecting not only the gut health in susceptible neonates but also has been proven to be beneficial in reducing systemic infections and allergies due to its immunomodulatory functions. 2 The study was based upon finding correlation between maternal breast milk LF levels and stage of lactation, maternal characteristics, and macronutrients levels in breast milk. Although authors analyzed a large sample size of 111 lactating regional mothers contributing to a total of 207 breast milk samples, colostrum samples were a meagre 4%, while mature milk samples over-represented the whole sample population, contributing to more than 85% of the study findings. There also existed wide variability in timing of mature milk sample collection between week third of postpartum period to end of first year after pregnancy, with no information being provided on median and interquartile range of sample collection age. The authors have not mentioned the study duration and time gap between sample collection and analysis, as previously published studies have shown that there is a significant decline in both the macronutrients i.e., energy and fat levels which becomes particularly depleted after 3 months period of freezing the breast milk. 3 The study findings have conceded with the earlier published systematic review that had shown mean content of lactoferrin to be significantly higher in the colostrum phase with a median value of 3.03 g/L and a steady decline observed amongst transitional milk and mature milk, with values being 2.07 and 0.83 g/L, respectively. 4 Although the correlation has been seen with majority of all macronutrients except carbohydrates, the strength of correlation as seen through r value of Spearman’s correlation coefficient seems not good enough to predict a strong linear correlation. 5 Again a positive correlation has been depicted for maternal body mass index (with higher values seen with increasing BMI) and maternal parity (more in higher parity) although the clinical significance due to very low value of ‘r’ coefficient is questionable. Also the data of BMI versus LF levels seems to have significant heteroscedasticity, as the standard deviations of predicted variable (LF levels) monitored over different values of independent variable(maternal BMI) seem to show fanning effect on scatter plot, which makes it unsuitable for simple linear regression modeling. 6 It is also relevant to know certain maternal parameters such as maternal illness either preexisting maternal sickness (hypertension, diabetes, autoimmune diseases, cardiac diseases, drug intake) or those occurring during pregnancy (pregnancy induced hypertension, gestational diabetes mellitus, maternal anemia, sepsis etc.) and effect of mode of delivery. Similarly, it is also important to know details of neonatal parameters apart from gender such as gestational age, neonatal birth weight, twin birth, initial sickness, episodes of sepsis, and need of hospitalization, which have significant bearing on clinical implications of research but have not been included in their study findings by the authors.