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Sex differences in birth size and intergenerational effects of intrauterine exposure to Ramadan in Saudi Arabia
S H Alwasel1, Z Abotalib, J S Aljarallah
1Fetal Programming of Disease' Research Chair, Zoology Department, College of Science, King Saud University, Saudi Arabia.
Insights
Newborn sex differences in body proportions exist in Saudi Arabia. Fetal growth is affected by maternal Ramadan fasting, with boys showing longer length and girls having shorter gestation.
Area of Science:
- Human anatomy and physiology
- Reproductive health
- Perinatal development
Background:
- Sex-based differences in body proportions are observed at birth in European populations.
- Understanding these differences in other regions, like Saudi Arabia, is crucial for perinatal health.
- The impact of maternal lifestyle factors, such as religious fasting during Ramadan, on fetal development requires investigation.
Purpose of the Study:
- To investigate sex differences in newborn body size and proportions in Saudi Arabia.
- To determine if fetal growth is influenced by maternal fasting during the holy month of Ramadan.
- To explore potential sex-specific responses to maternal nutritional and metabolic changes during pregnancy.
Main Methods:
- A cross-sectional study involving 967 newborn babies (479 boys, 488 girls) in Unizah, Saudi Arabia.
- Measurement of key anthropometric parameters including head circumference, birth weight, and chest circumference.
- Statistical analysis to identify predictors of sex and to compare growth parameters based on maternal Ramadan exposure during gestation.
Main Results:
- Large head circumference was the strongest predictor of male sex.
- Female sex was associated with smaller head circumference, lower birth weight, and larger chest circumference.
- Mothers of boys were heavier with higher BMI; mothers of girls were taller.
- Boys born to mothers fasting during mid-gestation were longer; girls had shorter gestation periods compared to controls.
Conclusions:
- Findings suggest boys prioritize somatic and brain growth over visceral development, aligning with theories of differential resource allocation.
- Boys may be more responsive to immediate maternal diet, while girls' growth is influenced by long-term maternal nutrition and metabolism.
- This study provides novel evidence that maternal lifestyle changes during Ramadan can impact fetal development across generations.
Objectives:
In Europe, boys and girls have different body proportions at birth. We examined newborn babies in Saudi Arabia to determine the sex differences and whether fetal growth differed if the mother was in utero during Ramadan.
Methods:
We examined body size at birth among 967 babies (479 boys and 488 girls) born in Unizah, a small city in Saudi Arabia.
Results:
Large head circumference was the strongest single predictor of male sex. In a simultaneous regression, female sex was predicted by small head circumference (P < 0.001), low birth weight (P = 0.002), and large chest circumference (P = 0.008). The mothers of boys were heavier in pregnancy than the mothers of girls and had a higher body mass index, 31.7 kg/m(2) compared to 30.2 (P < 0.001). The mothers of girls, however, were taller than the mothers of boys, 158.6 cm compared to 157.4 (P = 0.001). Compared to babies whose mothers were not in utero during Ramadan boys whose mothers were in mid gestation during Ramadan were 1.2 cm longer (P = 0.005) while girls had a 0.4 week shorter gestation period (P = 0.04).
Conclusion:
Our findings are consistent with other evidence that boys are more ready than girls to trade off visceral development in utero to protect somatic and brain growth. They also support the hypothesis that boys are more responsive to their mother's current diet than girls, who respond more to their mother's life time nutrition and metabolism. They provide the first evidence that changes in the life style of pregnant women during Ramadan affect more than one generation.
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