Background Excess male morbidity and mortality is well recognised in neonatal medicine and infant health. In contrast, within global nutrition, it is commonly assumed that girls are more at risk of experiencing undernutrition. We aimed to explore evidence for any male/female differences in child undernutrition using anthropometric case definitions and the reasons for differences observed. Methods We searched: Medline, Embase, Global health, Popline and Cochrane databases with no time limits applied. Eligible studies focused on children aged 0–59 months affected by undernutrition where sex was reported. In the meta-analysis, undernutrition-specific estimates were examined separately for wasting, stunting and underweight using a random-effects model. Results 74 studies were identified: 44/74 studies were included in the meta-analysis. In 20 which examined wasting, boys had higher odds of being wasted than girls (pooled OR 1.26, 95% CI 1.13 to 1.40). 38 examined stunting: boys had higher odds of stunting than girls (pooled OR 1.29 95% CI 1.22 to 1.37). 23 explored underweight: boys had higher odds of being underweight than girls (pooled OR 1.14, 95% CI 1.02 to 1.26). There was some limited evidence that the female advantage, indicated by a lower risk of stunting and underweight, was weaker in South Asia than other parts of the world. 43/74 (58%) studies discussed possible reasons for boy/girl differences; 10/74 (14%) cited studies with similar findings with no further discussion; 21/74 (28%) had no sex difference discussion. 6/43 studies (14%) postulated biological causes, 21/43 (49%) social causes and 16/43 (37%) to a combination. Conclusion Our review indicates that undernutrition in children under 5 is more likely to affect boys than girls, though the magnitude of these differences varies and is more pronounced in some contexts than others. Future research should further explore reasons for these differences and implications for nutrition policy and practice.

Complementing a recent systematic review and meta-analysis which showed that boys are more likely to be wasted, stunted, and underweight than girls, we conducted a narrative review to explore which early life mechanisms might underlie these sex differences. We addressed different themes, including maternal and newborn characteristics, immunology and endocrinology, evolutionary biology, care practices, and anthropometric indices to explore potential sources of sex differences in child undernutrition. Our review found that the evidence on why sex differences occur is limited but that a complex interaction of social, environmental, and genetic factors likely underlies these differences throughout the life cycle. Despite their bigger size at birth and during infancy, in conditions of food deprivation, boys experience more undernutrition from as early as the foetal period. Differences appear to be more pronounced in more severe presentations of undernutrition and in more socioeconomically deprived contexts. Boys are more vulnerable to infectious disease, and differing immune and endocrine systems appear to explain some of this disadvantage. Limited evidence also suggests that different sociological factors and care practices might exert influence and have the potential to exacerbate or reverse observed differences. Further research is needed to better understand sex differences in undernutrition and the implications of these for child outcomes and prevention and treatment programming.

The study describes the patterns of concurrent wasting and stunting (WaSt) among children age 6–59 months living in the 1980s in Niakhar, a rural area of Senegal under demographic surveillance. Wasting and stunting were defined by z scores lower than −2 in weight for height and height for age. Both conditions were found to be highly prevalent, wasting more so before age 30 months, stunting more so after age 30 months. As a result, concurrent WaSt peaked around age 18 months and its prevalence (6.2%) was primarily the product of the two conditions, with an interaction term of 1.57 ( p < 10 ⁻⁶ ). The interaction was due to the correlation between both conditions (more stunting if wasted, more wasting if stunted). Before age 30 months, boys were more likely to be concurrently wasted and stunted than girls (RR = 1.61), but the sex difference disappeared after 30 months of age. The excess susceptibility of younger boys could not be explained by muscle mass or fat mass measured by arm or muscle circumference, triceps, or subscapular skinfold. Concurrent WaSt was a strong risk factor for child mortality, and its effect was the product of the independent effect of each component, with no significant interaction.

BackgroundCompleteness of vital registration remains very low in sub-Saharan Africa, especially in rural areas.ObjectivesTo investigate trends and factors in completeness of birth and death registration in Agincourt, a rural area of South Africa covering a population of about 110,000 persons, under demographic surveillance since 1992. The population belongs to the Shangaan ethnic group and hosts a sizeable community of Mozambican refugees.DesignStatistical analysis of birth and death registration over time in a 22-year perspective (1992–2014). Over this period, major efforts were made by the government of South Africa to improve vital registration. Factors associated with completeness of registration were investigated using univariate and multivariate analysis.ResultsBirth registration was very incomplete at onset (7.8% in 1992) and reached high values at end point (90.5% in 2014). Likewise, death registration was low at onset (51.4% in 1992), also reaching high values at end point (97.1% in 2014). For bi...

To the Editor—The journal's recent supplement on sex differences in susceptibility and response to infectious diseases was an excellent initiative for promoting research on a neglected topic of major interest [1–8]. If, in general, males show a higher susceptibility to many infectious diseases, the reviews displayed a number of infectious and autoimmune diseases for which females are more vulnerable. Differential vulnerability between males and females may come from exposure, infection (local or systemic), immune reaction, or a combination of these factors. Evidence came mainly from medicine, epidemiology (direct observation), and biology (animal models and in vivo observation). I address another dimension: demographic evidence.

Background: The mean age at menarche remains poorly documented in Africa. Aim: To document levels, trends, and determinants of mean age at menarche in selected African populations. Subjects and methods: The World Fertility Surveys recorded the age at menarche in 12 African countries. These surveys were conducted from 1977 to 1983 and were based on large representative samples of national populations. Demographic and Health Surveys provided trends in adult height for the same cohorts. Results: The mean age at menarche was higher in sub-Saharan Africa (14.5 years) than in North-Africa (13.5 years). Age at menarche was declining significantly in all sub-Saharan African countries, but only in one North-African country. The speed of decline in sub-Saharan Africa averaged 0.47 years for a 30-year period, comparable to the speed of decline in Europe. Sub-Saharan African countries with higher increase in female adult height also had larger declines in mean age at menarche. In multivariate analysis, trends in age at menarche were correlated with trends in adult height and child survival. Conclusion: In sub-Saharan Africa, age at menarche was undergoing a transition similar to that of European countries in the nineteenth century and was associated with improving health of young women. North-African countries were more advanced.