gms | German Medical Science

Introduction: The prenatal roots of airways diseases such as wheezing are traced back to gene-environment interactions. Primarily maternal smoking has been named as important environmental risk factor [1]. Lopuhaä et al. [2] showed that prenatal famine exposure increases risks for obstructive airways disease, and especially for wheezing when exposure occurred in mid-gestation. Explanations are based on fetal programming theory, suggesting that impaired development of organs during critical growth periods can remain latent for a long time and show its impacts only in adulthood [3]. Effects of less extreme nutritional exposures on lung functioning have thus far hardly been investigated. We aim to fill this gap by studying effects of Ramadan in utero on wheezing in adulthood.

Methods: We use data from four waves of the Indonesian Family Life Survey (waves 1-4). The Indonesian Family Life Survey is a longitudinal survey study and individuals are asked about their health status repeatedly, inter alia whether they experienced wheezing in the last 4 weeks before the interview.

A large share of the Indonesian population is Muslim (more than 89 % in our sample) and a majority of Indonesian pregnant women are thought to fast during Ramadan [4]. Prenatal Ramadan exposure has been linked to multiple other health conditions [5]. Taking the sub sample of Muslims (26,515 observations), we determine whether subjects experienced a Ramadan in utero by calculating overlap between Ramadan and the 266 days before birth. Our control group consists of Muslims without such overlap. Our analyses are logistic regressions that adjust for age, age squared, sex, birth month (Ramadan each year occurs on different dates) and IFLS wave.

Results: Our results show that wheezing prevalences are increased in those exposed to Ramadan during any phase of pregnancy. However, effects are most pronounced for those older than 45 years and particularly male Muslims. This fits with medical theory suggesting that the lung system has multiple critical growth periods and fetal programming theory proposing that impacts of in-utero exposures often only show after the reproductive age.

Discussion: Our findings confirm that the fetal origins hypothesis is also relevant for milder events during gestation. In particular, our research helps pregnant Muslim women to take informed decisions about their behavior during Ramadan. With more than 22 % of the world population adhering to the religion of Islam, our findings are relevant for a large subgroup of the population.

It is important to note that it to date remains unclear from what the effects of prenatal exposure to Ramadan stem. Besides the actual fasting, Ramadan implicates changed sleeping hours, activity levels during the day and the abstinence from medication during daylight hours. Those factors may all affect the in-utero environment.

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Der Beitrag wurde bereits vorgestellt: The Power of Programming 2016 - October 13-15, 2016 in Munich