Lack of head sparing following third-trimester caloric restriction among Tanzanian Maasai

Abstract

The reduction of food intake during pregnancy is part of many cultural and religious traditions around the world. The impact of such practices on fetal growth and development are poorly understood. Here, we examined the patterns of diet intake among Maasai pregnant women and assessed their effect on newborn morphometrics. We recruited 141 motherinfant pairs from Ngorongoro Conservation Area (NCA) in Northern Tanzania and quantified dietary intake and changes in maternal diet during pregnancy. We obtained measurements of body weight (BW) and head circumference (HC) at birth. We found that Maasai women significantly reduced their dietary intake during the third trimester, going from an average of 1601 kcal/day during the first two trimesters to 799 kcal/day in the final trimester. The greatest proportion of nutrient reduction was in carbohydrates. Overall, 40% of HC Z-scores of the NCA sample were more than 2 standard deviations below the WHO standard. Nearly a third of neonates classify as low birth weight (< 2500g). HC was smaller relative to BW in this cohort than predicted using the WHO standard. This contrasts markedly to a Tanzanian birth cohort obtained at the same time in an urban context in which only 12% of infants exhibited low weight, only two individuals had HC Z-scores < 2 and HC's relative to birth weight were larger than predicted using the WHO standards. The surprising lack of head sparing in the NCA cohort suggests that the impact of third trimester malnutrition bears further investigation in both animal models and human populations, especially as low HC is negatively associated with long term health outcomes.

The Carbohydrate Threshold in Pregnancy and Gestational Diabetes: How Low Can We Go?

“…Across studies, fetal growth tracked consistently with carbohydrate intake such that BWs are lower and incidences of SGA are higher with lower carbohydrate intake. While several studies did not control for total EI [ 30 , 31 , 35 ], the same response was observed in the large cohort study from Japan which controlled for EI [ 36 ]. The effects of a carbohydrate intake below the IOM recommendation of 175 g/d remain unclear, particularly intakes below the threshold at which women may experience ketonemia (<50 g/d outside of pregnancy) [ 39 , 62 , 63 ].…”

“…However, whether total EI also fluctuated seasonally was unclear. Among pastoralist pregnant women in Tanzania [ 35 ], reduced EI during late pregnancy is a cultural tradition observed to prevent delivery complications related to larger BW. Women were found to reduce their EI by nearly 50% and carbohydrate intake by 64% to ~100 g/d.…”

“…For example, an in vitro study of trophoblasts cultured from first trimester chorionic villi demonstrated that ketones suppress trophoblast uptake of glucose, jeopardizing glucose transfer across the placenta [ 18 ]. Evidence evaluated here showed reductions in head circumference occurred following ~50% maternal energy restriction with 100 g carbohydrate/d [ 35 ].…”

“…After elimination of duplicates, and studies that did not meet inclusion criteria, 11 reports met inclusion criteria ( Table 1 , Table 2 , Table 3 and Table 4 ). Of these, 9 reported data from observational cohort or cross-sectional studies [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ], 1 from an original RCT [ 39 ], and 1 from a secondary analysis of an RCT [ 40 ]. Figure 1 shows the distribution of carbohydrate intakes reported across these studies.…”

Intermittent Fasting, Dietary Modifications, and Exercise for the Control of Gestational Diabetes and Maternal Mood Dysregulation: A Review and a Case Report

“…Interestingly, all of these changes were not detected latterly in first generation pups during pregnancy, indicating that minor epigenetic changes induced by caloric restriction do not trigger persistent metabolic changes in the progeny [ 20 ]. It is noteworthy that a reduction of total caloric intake (799 kcal/day) by Tanzanian Maasai women during the third trimester is associated with the occurrence of low birth weight (<2500 g) in one third of the neonates [ 92 ]. Therefore, methods that involve regulation of food intake while maintaining adequate caloric intake would be safer than excessive caloric restriction.…”