Antenatal Food Avoidances in Madagascar Suggest an Evolutionary Link Between Subsistence Patterns, Carbohydrate...

We aimed to test if different subsistence patterns shaped different antenatal eating behaviors in Madagascar, and to investigate if reasons given for maternal dietary restrictions disclosed actual biological pressures on pregnancy.

We conducted semi-structured interviews with 312 participants to investigate differences in avoided food types during pregnancy, reasons, and infants' weight between subsistence patterns (agriculture, agriculture-husbandry/fishery, fishery), and associations between food types and reasons (Chi-squared, Fisher's, and Kruskal-Wallis test in R and SPSS). Secondary questions investigated regional variance in food avoidance (PCA), the association between the carbohydrate content of avoided foods and the fear of difficult delivery (regression analysis), and institutional and non-institutional influences on dietary proscriptions (heatmap).

Agriculturalists avoided more plant-based foods than fishers for the fear of difficult delivery due to large infants. Infants' weights at birth did not vary significantly across subsistence modes. Dietary norms were reinforced by an interplay between institutional and non-institutional advisors.

Food avoidances during pregnancy among Malagasy agriculturalists and fishers differ in targets and reasons. Avoided foods reflect staple diets, while the fear of difficult labor due to large infant size in relation to carbohydrate-rich foods among agriculturalists overlaps with a high incidence of obstructed labor in agricultural regions. Therefore, different subsistence modes affect antenatal behavior priorities differently. Taboos and sources of advice on maternal diet are fluid systems. We highlight the urgent need to better understand the determinants of obstructed labor and the patterns of spread of antenatal practices in Madagascar.