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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Season of birth may relate to physical fitness in children

A recent study published in International Journal of Sports Medicine has found that children born in November and October were more athletic than children born in other months.

Seasonality plays an important role in vitamin D synthesis via sun exposure. Sun exposure is greatest in the summer, which means it is easier to produce vitamin D from sunlight during this time of year.

Researchers from Essex University recruited 8,550 children between 10 and 16 years of age. They wanted to determine if month of birth affects athleticism.

The children were tested on three different aspects of physical fitness: endurance, hand grip strength, and lower body power.

The results revealed that athletic performance varied significantly according to the children’s month of birth.

Children born in November were overall more fit with the greatest endurance and lower body power and a high degree of hand grip strength.

The results also found that those born in April and June were the least physically fit. The study found that children born in November could run 10% faster, jump 12% higher, and have 15% more power than those born in April.

The researchers proposed that the observed difference in athletic ability may be due to seasonal differences in vitamin D levels. If a child is born in late summer or autumn, it is suggested that the mother (thus, her child too) receives more vitamin D at the end of her pregnancy through the summer months.


Sandercock, et al. Athletic Performance and Birth Month: Is the Relative Age Effect More than just Selection Bias? International Journal of Sports Medicine, 2014

2 Responses to Season of birth may relate to physical fitness in children

  1. That kids born in Oct, Nov are more into sports was found about 20 years ago.
    It is due to being the oldest/strongest when chosen for sports teams in Sept, when school starts.
    Think about it.
    Who will be strongest 13 year old player when school starts in Sept.
    a kid who is 13.9 years old (birthday in Oct/Nov)
    or a kid who is 13.1 years old (birthday in August)

  2. Anh Phan says:

    If the pregnant mother stay inside the house during summer, is there a possibility that the kid born healthy? There are many factor affect the health of the kids. I think vitamin D play an important role for my health, I was born November, I was very active, I loved the sun , as a kid I ran freely outside without sunscreen, I think because of that, I grew much taller than my other sisters, rarely got sick, skin heal very fast. However, some kids also have irreversible sun damage, maybe because these kids already have malnutrition problem, their body lack antioxidant to fight the damage of UV light. We should consider these factors.