Many girls in Africa have insecure access to food, that is, they worry about getting enough food, and they sometimes eat less than they want, or go without food. There are two theories about how this might affect the onset of menstruation (menarche). One is that the limitations in energy and nutrition might slow development, resulting in a later menarcheal age. The other evolutionary theory is that early life stressors trigger a shift in so-called life history strategy, leading to accelerated development and an earlier menarche. In a recent article in the journal Reproductive Biology and Endocrinology, researchers from Ethiopia, Belgium and the USA presented data from the first two years of the Jimma Longitudinal Family Survey of Youth to contrast these two theories. The survey was conducted in southwest Ethiopia, sampling across rural, urban and small town areas and including boys and girls. Data about the household and the girls’ experience of food insecurity were assessed by questionnaire in the first year, and in the second year girls were asked whether and how old they were when they first menstruated. 900 girls, with an average age of 14.8 at baseline, participated in both of the first two years of the five year study.

Overall, girls who reported some degree of food insecurity (n=225/900) were similar in age, region (urban, semi-urban, rural), and nutritional status (whether they were short for age). However, they were more likely to be in a male-headed household, tended to be in middle income rather than high income households, and reported more domestic work than those reporting food security. Overall, girls with moderate to severe food insecurity were significantly less likely to have undergone menarche. The estimate of the age at menarche was one year older for Ethiopian girls who have insecure access to food.

Girls in the developing world experience menarche at an older age than those in the developed world, and, with development, other countries are experiencing the secular change of earlier age at menarche. In this study, the estimated age at menarche was younger in urban centres (14) than in semi-urban or urban areas (15), and girls in high income households had an earlier menarche, suggesting that improved food security may be part of the puzzle explaining these changes.