Discussion
lean mass accretion, adiposity, FM
ADIPOSITY
Our study found that prenatal BEP led to a higher maternal and newborn FFMI without significant effects on FMI. The positive effect of prenatal BEP on maternal FFMI was found to be larger among mothers with a better nutritional status at baseline (i.e., BMI ≥21.0 kg/mOur results are in contrast to those from the MISAME-II trial conducted in the same health district between 2006 and 2008. MISAME-II found elevated cord blood leptin concentration, indicating larger newborn FM accretion [A number of trials have evaluated the effects of prenatal LNS on maternal and newborn outcomes [Various possible explanations can be forwarded for our finding that prenatal BEP in mothers and their newborns led to FFM accretion rather than FM accretion. First, the composition of the BEP supplement used could possibly influence the balance between FFM and FM tissue accretions. Diets and supplements containing animal-source proteins, especially those from dairy products, support lean mass accretion better than diets or supplements containing only plant-based protein sources [Subgroup analyses showed that prenatal BEP was more efficacious in increasing maternal FFM index in the women from food secure households or with a more adequate energy balance (i.e., baseline BMI ≥21.0 kg/mThe observed effects of prenatal BEP on newborn FFMI can be seen in relation to the subsequent modest effect of prenatal BEP on linear growth achieved at 6 months of age (0.11 z-score; 95% CI: 0.01, 0.21; A major strength of our study was the direct measurement of body composition using the deuterium dilution method, which enables robust assessment that can be implemented at scale in a rural field setting. We were also able to achieve a high adherence to both the BEP and IFA supplements through daily home visits by community-based study workers who observed supplement intake. A dietary intake survey conducted in a subsample of the study participants also ruled out any substitution effect of the BEP on usual dietary patterns [The study has several limitations that need to be addressed. About 18% of the newborn outcome data was missing mainly due to saliva samples not being collected or unreadable identification numbers on cryotubes, whereas we anticipated a 10% loss when designing the study. However, the occurrence of missing data was not specific to any of the study group and maternal and household characteristics were comparable between study groups. Therefore, we argue that the missing data are unlikely to have biased group comparisons. Maternal body composition using the deuterium dilution method was not measured at baseline. As such, we were only able to consider baseline adjustment in our models for proxy variables of body composition such as BMI and arm fat index. Lastly, having follow-up body composition measurements would have revealed whether observed effects are sustained in the long term.In conclusion, our study demonstrated that prenatal BEP supplementation has positive effects on newborn and maternal FFM accretion without significant alteration of FMI. The absence of any effects of BEP on fat mass accretion in both newborn and mother addresses the possible concern that prenatal BEP would lead to excess adiposity and associated long-term health risks.