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Abstract
Vitamin D is a secosteroid with an endocrine mechanism of action which is sequentially synthesized in humans in the skin, liver and kidneys. The active hormone, 1α,25-dihydrocholecalciferol [1,25(OH)^sub 2^D^sub 3^], is often considered only in terms of its role in controlling calcium and phosphorus homeostasis. However, cumulative evidence points to the presence of vitamin D receptors in many tissues. The present article summarizes key points regarding the participation of vitamin D in pregnancy and breastfeeding. During pregnancy, sufficient vitamin D concentrations are needed not only to address the growing demand for calcium on the part of the fetus, but also to participate in fetal growth, development of the nervous system, lung maturation and fetal immune system function. Hypovitaminosis D has been related to the development of diabetes, preeclampsia and fetal neurological disorders. During pregnancy and lactation, calcium from the maternal skeleton is mobilized, with a rise in bone turnover and a reduction in bone mass. It is advisable for pregnant and nursing women to maintain adequate levels of vitamin D, through small doses of solar exposure to facilitate natural formation of the hormone or by ingesting appropriate vitamin supplements. Further studies are needed to clarify the many gaps in knowledge and elucidate the role of vitamin D in the context of reproduction. Confirmation of experimental observations relating to the risks of hypovitaminosis D would have important public health implications.
Keywords: Vitamin D, hypovitaminosis D, pregnancy, breastfeeding, fetal growth, bone turnover, adequate levels of vitamin D
Introduction
In the mid-XVII century, descriptions appeared in Holland and England of a disease called rickets, English disease, Morbus puerili Anglorum or Glisson's disease [1,2], which was found to be widely prevalent among the populations of large contaminated cities with scant natural sunlight. In the XIX century, the Polish professor Sniadecki confirmed the high frequency of rickets in crowded urban areas, and stressed the potent effect of sunlight in healing the disease although the results of his research had no impact upon the international scientific community of the time. In 1919, Edward Mellamby casually noticed that the dogs used in his studies, which had never been exposed to sunlight, developed skeletal alterations similar to those seen in children with rickets, and that such alterations could be avoided...