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Babies born in summer have higher birth weight, taller adult height

In the United Kingdom and Ireland, birth month was found to be associated with birth weight, age of puberty onset and adult height, according to recently published data.  

“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,” John Perry, PhD, MRC Epidemiology Unit at the University Of Cambridge School Of Clinical Medicine, said in a press release.

To assess the correlation between birth month and birth weight, age of puberty onset, adult height and BMI, Perry and colleagues analyzed data on roughly 450,000 participants from the U.K. Biobank study.

Results demonstrated that babies who were born in June, July and August were more likely to weigh more at birth and have taller adult heights, compared with babies born during other months. Similar patterns were observed with total hours of sunshine during the second trimester.

Among women, those born in June, July or August were more likely to begin puberty at an older age.

No correlation was seen between birth month and adult BMI.

The researchers noted that these results, along with those from previous studies may indicate the importance of in utero exposure to vitamin D and other exposures, but more research is necessary.

“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 benefit. We think that vitamin D exposure is important and our findings will hopefully encourage other research on the long-term health effects of early life vitamin D on puberty timing and health,” Perry said in a press release. – by Casey Hower

Disclosures: The researchers report no relevant financial disclosures.