Food taboos during pregnancy: meta-analysis on cross cultural differences suggests specific, diet-related pressures on childbirth among agriculturalists

Pregnancy is the most delicate stage of human life history as well as a common target

of food taboos across cultures. Despite puzzling evidence that many pregnant women

across the world reduce their intake of nutritious foods to accomplish cultural norms,

no study has provided statistical analysis of cross-cultural variation in food taboos

during pregnancy. Moreover, antenatal practices among forager and agriculturalists

have never been compared, despite subsistence mode being known to affect staple foods

and lifestyle directly. This gap hinders to us from understanding the overall threats

attributed to pregnancy, and their perceived nutritional causes around the world. The

present study constitutes the first cross-cultural meta-analysis on food taboos during

pregnancy. We examined thirty-two articles on dietary antenatal restrictions among

agricultural and non-agricultural societies, in order to: (i) identify cross-culturally

targeted animal, plant and miscellaneous foods; (ii) define major clusters of taboo

focus; (iii) test the hypothesis that food types and clusters of focus distribute differently

between agricultural and non-agricultural taboos; and (iv) test the hypothesis that food

types distribute differently across the clusters of taboo focus. All data were analysed

in SPSS and RStudio using chi-squared tests and Fisher’s exact tests. We detected a

gradient in taboo focus that ranged from no direct physiological interest to the fear

of varied physiological complications to a very specific concern over increased birth

weight and difficult delivery. Non-agricultural taboos were more likely to target

nondomesticated animal foods and to be justified by concerns not directly linked to the

physiological sphere, whereas agricultural taboos tended to target more cultivated and

processed products and showed a stronger association with concerns over increased

birth weight. Despite some methodological discrepancies in the existing literature on

food taboos during pregnancy, our results illustrate that such cultural traits are useful

for detecting perception of biological pressures on reproduction across cultures. Indeed,

the widespread concern over birth weight and carbohydrate rich foods overlaps with

clinical evidence that obstructed labor is a major threat to maternal life in Africa,

Asia and Eurasia. Furthermore, asymmetry in the frequency of such concern across

subsistence modes aligns with the evolutionary perspective that agriculture may have

exacerbated delivery complications. This study highlights the need for the improved

understanding of dietary behaviors during pregnancy across the world, addressing the

role of obstructed labor as a key point of convergence between clinical, evolutionary

and cultural issues in human behavior.