New findings uncovered that women born during summer months were more likely to be healthy as adults in comparison to babies born in other seasons. The findings suggest that more sunlight, which contributes to higher vitamin D for pregnant mothers in their second trimester, could potentially be the reason.
Birth month was also found to contribute to a baby’s weight at birth and when puberty begins in females – both aspects affect long-term health.
Researchers at the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge conducted their study on whether birth month affected birth weight, puberty onset and adult height. Summertime babies were found to be slightly heavier, taller and experienced puberty slightly later compared to winter babies.
Study lead, Dr. John Perry, said, “When you were conceived and born occurs largely ‘at random’ – it’s not affected by social class, your parents’ ages or their health – so looking for patterns with birth month is a powerful study design to identify influences of the environment before birth.”
Data from 450,000 men and women from the UK was compared. Results found those born in July or August were heavier at birth and taller as adults. Females born in the summer were also found to start puberty later – an indication of better adult health.
Dr. Perry added, “This is the first time puberty timing has been robustly linked to seasonality. We were surprised, and pleased, to see how similar the patterns were on birth weight and puberty timing. Our results show that birth month has a measurable effect on development and health, but more work is needed to understand the mechanisms behind this effect.”
Researchers suggest sunlight exposure and vitamin D may play a role in the differences between summertime babies and winter babies.
Dr. Perry concluded, “We don’t know the mechanisms that cause these season of birth patterns on birth weight, height, and puberty timing. We need to understand these mechanisms before our findings can be translated into health benefits. We think that vitamin D exposure is important and our findings will hopefully encourage other research on the long-term effects of early life vitamin D on puberty timing and health.”
The findings were published in Heliyon.