In septentrional countries without vitamin D supplementation of milk a
nd dairy products, many pregnant women are vitamin D deficient. Conseq
uently vitamin D deficiency is present in many newborn infants, which
may lead to neonatal hypocalcemia and vitamin D deficient rickets. A p
revention of vitamin D deficiency is therefore a necessity in pregnant
women through a vitamin D supplementation. This can be done either by
a daily supplementation of 400 IU during all pregnancy, or a daily su
pplementation of 1 000 IU during the third trimester, or by giving a u
nique dose of 100 000 to 200 000 IU during the seventh month of pregna
ncy.