Impact of Vitamin D Supplementation on Lactation Associated Bone Loss

Studies have shown that lactation is associated with a loss of bone density from four to seven percent at the spine and hip among women who lactate for six months. Decline in bone density with lactation occurs rapidly. Although bone density increases after weaning, there is controversy on whether or not it is completely restored. Epidemiological studies find no significant negative impact of lactation on bone mass or fractures, and in fact there is evidence that lactation has a positive effect on bone mass. We think that interventions that attenuate this physiologic loss of bone that is associated with lactation and accelerate restoration of bone mass after weaning may result in improved long term bone mass and diminished fracture risk.

Adequate vitamin D stores are necessary for skeletal health. Vitamin D deficiency is pronounced in women of child bearing age as well as pregnant women in the United States. This study will provide important information about whether vitamin D supplementation may positively impact the normal physiologic loss of bone mass that is observed during lactation. Recruitment will begin while subjects are pregnant in order to expedite entry into the study in the immediate post-partum period. If subjects are deemed eligible during pregnancy, contact information to include name, address, expected delivery date and two contact phone numbers will be obtained. Subjects will be contacted two weeks prior to expected delivery date and then again at expected delivery date. Subjects will be followed for a total of 18 months.

Inclusion Criteria: Fully lactating mothers age 18 and up Within 1 month after delivery Plan to breast feed for at least 6 months Exclusion Criteria: Known metabolic bone disease Chronic renal insufficiency Chronic corticosteroid use Eating disorder Estrogen containing hormonal contraception use Daily use of >400IU Vitamin D supplementation Delivery of Multiples Delivery of a singleton with a birth weight of <2500 grams Preterm delivery of baby History of kidney stones