Pregnant women with relatively low amounts of vitamin D in their diets tend to give birth to smaller infants, a new study suggests.
Canadian researchers found that pregnant women who drank little milk or had a lower vitamin D intake tended to have smaller babies than women with higher intakes.
Fortified milk is a primary source of vitamin D in Western diets, and the nutrient may be the main reason why women's milk consumption was linked to birthweight, according to the researchers.
"Absence of vitamin D seems to be what's driving this," study co-author Dr Kristine G. Koski, of McGill University in Montreal, told Reuters Health.
What's more, the study suggests, vitamin D deficiency is not required to potentially affect fetal growth.
Although vitamin D intake was lower among women who avoided milk, it was still, on average, within the recommended range. This suggests that pregnant women need more than the current "adequate" intake level for vitamin D - 5 micrograms for adults age 50 and younger, Koski said.