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1. Childhood body mass is positively associated with cesarean birth in Y ucatec M aya subsistence farmers

   https://doi.org/10.1002/ajhb.22920  

   Veile, Amanda ; Kramer, Karen L. ( October 2016 , American Journal of Human Biology)

   The epidemiologic link between cesarean birth and childhood obesity is unresolved, partly because most studies come from industrialized settings where many post‐birth factors affect the risk for obesity. We take advantage of an unusual ethnographic situation where hospital and cesarean birth modes have recently been introduced among Yucatec Maya subsistence farmers, but young children have had minimal exposure to the nutritional transition. While we expect to find very low rates of childhood obesity, we predict that cesarean‐born children will be larger and heavier than vaginally born children.

   Weight and height were collected monthly on 108 children aged 0–5 (3576 observations total). Birth mode and birthweight were collected by maternal interview. Data were analyzed using linear mixed models that compare child growth [Maya population‐specificZ‐scores for weight‐for‐age and body mass index‐for‐age (WAZ and BMIZ)] in cesarean and vaginally born children aged 0–5 years.

   The cesarean rate was 20%, no children were obese, and 5% were overweight. Cesarean birth was a significant predictor of child WAZ and BMIZ after accounting for maternal effects, child birthweight, and sex. Children who were born by cesarean to mothers with high BMI had the highest WAZ of all children by 5 years of age, and the highest BMIZ of all children at all ages.

   Cesarean‐born Maya children had higher BMI than vaginally born children, even in the absence of many known confounding factors that contribute to childhood obesity. Child growth was most sensitive to birth mode when mothers had high BMI.

    

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2. No impact of developmental conditions on serum estradiol levels among Bangladeshi women in the UK and Bangladesh

   https://doi.org/10.1002/ajhb.23631  

   Chaney, Carlye ; Begum, Khurshida ; Núñez‐de la Mora, Alejandra ; Sievert, Lynnette L. ; Muttukrishna, Shanthi ; Harries, Victoria ; Sharmeen, Taniya ; Murphy, Lorna ; Gunu, Richard ; Chowdhury, Osul ; et al ( June 2021 , American Journal of Human Biology)

   While many aspects of female ovarian function respond to environmental stressors, estradiol (E2) appears less sensitive to stressors than progesterone, except under extreme ecological conditions. However, earlier studies relied on saliva samples, considered less sensitive than blood. Here, we investigated E2 variation among 177 Bangladeshi and UK white women, aged 35–59, using single serum samples. Bangladeshi women either grew up in Sylhet, Bangladesh (exposed to poor sanitation, limited health care, and higher pathogen loads but not poor energy availability), or in the UK.

   We collected samples on days 4–6 of the menstrual cycle in menstruating women and on any day for post‐menopausal women. Participants included: (i) Bangladeshi sedentees (n = 36), (ii) Bangladeshis who migrated to the UK as adults (n = 52), (iii) Bangladeshis who migrated as children (n = 40), and (iv) UK white women matched for neighborhood residence to the migrants (n = 49). Serum was obtained by venipuncture and analyzed using electrochemiluminescence. We collected anthropometrics and supplementary sociodemographic and reproductive data through questionnaires. We analyzed the data using multivariate regression.

   E2 levels did not differ between migrant groups after controlling for age, BMI, physical activity, psychosocial stress, parity, and time since last birth (parous women). Paralleling results from salivary E2, serum E2 did not differ among women who experienced varying developmental conditions.

   Our results reinforce the hypothesis that E2 levels are stable under challenging environmental conditions. Interpopulation variation may only arise under chronic conditions of extreme nutritional scarcity, energy expenditure, and/or high disease burdens.

    

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3. DHEAS and nutritional status among Sidama, Ngandu, and Aka children: Effects of cortisol and implications for adrenarche

   https://doi.org/10.1002/ajhb.23881  

   Helfrecht, Courtney ; Wang, Hui ; Dira, Samuel J. ; DeAvila, David ; Meehan, Courtney L. ( February 2023 , American Journal of Human Biology)

   Adrenarche, the biological event marked by rising production of dehydroepiandrosterone and its sulfate (DHEAS), may represent a sensitive period in child development, with important implications for adolescence and beyond. Nutritional status, particularly BMI and/or adiposity, has long been hypothesized as a factor in DHEAS production but findings are inconsistent, and few studies have examined this among non‐industrialized societies. In addition, cortisol has not been included in these models. We here evaluate effects of height‐ (HAZ), weight‐ (WAZ), and BMI‐ (BMIZ) for‐age on DHEAS concentrations among Sidama agropastoralist, Ngandu horticulturalist, and Aka hunter‐gatherer children.

   Heights and weights were collected from 206 children aged 2–18 years old. HAZ, WAZ, and BMIZ were calculated using CDC standards. DHEAS and cortisol assays were used to determine biomarker concentrations in hair. Generalized linear modeling was used to examine effects of nutritional status on DHEAS concentrations, as well as cortisol, controlling for age, sex, and population.

   Despite the prevalence of low HAZ and WAZ scores, the majority (77%) of children had BMIz‐scores >−2.0 SD. Nutritional status has no significant effect on DHEAS concentrations, controlling for age, sex, and population. Cortisol, however, is a significant predictor of DHEAS concentrations.

   Our findings do not support a relationship between nutritional status and DHEAS. Instead, results suggest an important role for stress and ecology in DHEAS concentrations across childhood. Specifically, effects of environment via cortisol may be influential to patterning of DHEAS. Future work should investigate local ecological stressors and their relationship to adrenarche.

    

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4. Thirty-five years later: Long-term effects of the Matlab maternal and child health/family planning program on older women’s well-being

   https://doi.org/10.1073/pnas.2101160118  

   Barham, Tania ; Champion, Brachel ; Foster, Andrew D. ; Hamadani, Jena D. ; Jochem, Warren C. ; Kagy, Gisella ; Kuhn, Randall ; Menken, Jane ; Razzaque, Abdur ; Root, Elisabeth Dowling ; et al ( July 2021 , Proceedings of the National Academy of Sciences)

   Family planning programs are believed to have substantial long-term benefits for women’s health and well-being, yet few studies have established either extent or direction of long-term effects. The Matlab, Bangladesh, maternal and child health/family planning (MCH/FP) program afforded a 12-y period of well-documented differential access to services. We evaluate its impacts on women’s lifetime fertility, adult health, and economic outcomes 35 y after program initiation. We followed 1,820 women who were of reproductive age during the differential access period (born 1938–1973) from 1978 to 2012 using prospectively collected data from the Matlab Health and Demographic Surveillance System and the 1996 and 2012 Matlab Health and Socioeconomic Surveys. We estimated intent-to-treat single-difference models comparing treatment and comparison area women. MCH/FP significantly increased contraceptive use, reduced completed fertility, lengthened birth intervals, and reduced age at last birth, but had no significant positive impacts on health or economic outcomes. Treatment area women had modestly poorer overall health (+0.07 SD) and respiratory health (+0.12 SD), and those born 1950–1961 had significantly higher body mass index (BMI) in 1996 (0.76 kg/m²) and 2012 (0.57 kg/m²); fewer were underweight in 1996, but more were overweight or obese in 2012. Overall, there was a +2.5 kg/m²secular increase in BMI. We found substantial changes in lifetime contraceptive and fertility behavior but no long-term health or economic benefits of the program. We observed modest negative health impacts that likely result from an accelerated nutritional transition among treated women, a transition that would, in an earlier context, have been beneficial.

    

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5. Household conditions modulate associations between cesarean delivery and childhood growth

   https://doi.org/10.1002/ajpa.24563  

   Veile, Amanda J. ; Kramer, Karen Leslie ; Otárola‐Castillo, Erik ( July 2022 , American Journal of Biological Anthropology)

   Cesarean delivery is associated with childhood obesity in urbanized and sanitized environments, but this is not well‐studied across broader epidemiologic settings. We examine birth mode, household conditions, and child growth in a Yucatec Maya farming community with limited sanitary infrastructure. We test the hypotheses that household infrastructure and epidemiologic conditions: (1)modulateassociations between cesarean delivery and growth, and (2) are more strongly associated with growth compared to birth mode.

   Birth mode, household characteristics (construction materials/waste disposal/water variables) and growth were examined in 106 children (0–5 years, 3554 longitudinal observations). Ahousehold modification index(HMI) was created to indicate “baseline” (more traditional) versus “modified” (more modernized) houses. Weight/height/BMI Z‐scores (WHO‐standards) were modeled with respect to HMI and birth mode using nested generalized linear mixed‐effects models. A series of interaction models were then compared.

   Four household modification variables (concrete roof and floor, latrine/septic tank, burning trash) were associated with greater growth gains and used to compose the HMI. Cesarean delivery was associated with slightly higher Z‐scores for most anthropometric outcomes. HMI modulated the association between birth mode and children's weight and height, but not BMI, trajectories. Weight and BMI Z‐scores, but not height Z‐scores, were higher at all ages under high HMI (“modified”) versus low HMI (“baseline”) conditions regardless of birth mode.

   Understudied household conditions can modulate the association between cesarean delivery and childhood growth. These findings contribute to a large body of literature linking cesarean delivery to a variety of child health outcomes including obesity.

    

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