gms | German Medical Science

Background: The human brain undergoes critical developmental phases during the prenatal period. Maternal nutrition during pregnancy and other environmental influences have been shown to be associated with offspring neuronal structure and function, with implications for postnatal cognitive development across the life course [1]. Previous studies have used exposure to Ramadan in utero as a proxy for maternal malnutrition to investigate its effects on offspring outcomes. Even though pregnant Muslim women are allowed to be exempted from fasting during this holy month, many of them still decide to fast. So far, evidence supporting the link between Ramadan during pregnancy and children’s performance at school and in the labor market still remains limited [2]. This study investigates associations between Ramadan during pregnancy and offspring performance in the Dutch Central Final Test (CITO), which plays an important role in the admission of the majority of children to secondary schools in the country.

Methods: This project uses population-based data obtained from Statistics Netherlands (CBS). Our sample includes 174,468 migrant children aged 11 to 12, who took the CITO test between 2006 and 2021. Their migration background originates from countries where the Muslim population constitutes at least 70%. Since most of Muslim immigrants in the Netherlands fast daily during Ramadan, we used this as a proxy for Ramadan observance in pregnancy [3]. We compare standardized total test scores (ranging from 501 to 550 points, consisting of Math, Language, and Information Processing modules) of Muslim children exposed to Ramadan in utero with those of nonexposed Muslims. Following previous literature, we compared Muslims born in the 9 months after a Ramadan with Muslims for whom no Ramadan occurred during gestation in an intent-to-treat framework using OLS. We additionally controlled for gender, test year, birth month, maternal age, maternal age squared, parental income, and general academic performance (proxied by the age at which the test was taken). We further extended these analyses to the difference-in-difference (DID) framework in which 108,268 non-Muslim immigrants were included as a further control group, in order to better control for season-of-birth effects [4].

Results: Ramadan overlap during the second and third trimesters of pregnancy was associated with approximately one-third of a point lower in standardized test scores. These results are significant at 5% level, consistent in both OLS and DID models, and are mainly driven by the Language module. Our robustness checks using restricted samples of same-gender children showed that the effects are significant for female offspring only.

Conclusions: Muslim children in The Netherlands who were prenatally exposed to Ramadan are more likely to perform worse in the CITO tests than unexposed Muslim children. This study provides new evidence on the link between in-utero nutritional shocks and changes in the structure and function of the human brain, potentially influencing long-term cognitive development in offspring. Considering that Muslim births represent approximately 31% of total global births [5], millions of babies could be impacted by their mothers' fasting during Ramadan annually.

The authors declare that they have no competing interests.

The authors declare that an ethics committee vote is not required.