TUESDAY, 20 OCTOBER 2015The study, lead by Dr. Perry from the Medical Research Council (MRC) Epidemiology Unit, used a long-term data-set from the UK Biobank Study, a major national health resource, to analyse how different traits relate to the month when a baby is born. Using information from 500,000 people the group found that individuals born between June and August had a larger weight at birth and developed into taller adults than those born in other months.
Babies born in December showed the exact opposite pattern. Furthermore, they also found a relationship between the birth month and the likelihood of studying beyond the age of 16. This effect was particularly strong between August and September: Babies born in the later were much more likely to study beyond the age 16 than babies born in the former. These correlations (non-causal relationships) remained significant even when statistically controlling for important factors, like socio-economic rank, smoking and educational attainment of the parents.
What could be driving this effect remains unknown, but one possibility is that it depends on how much vitamin D the mother gets during pregnancy. Mothers giving birth in the summer receive more sunlight (and hence a higher vitamin D exposure) in the second trimester of their pregnancies, at least in the UK, where the data came from. However, this idea remains to be properly tested by future work.
Written by Ornela De Gasperin.