Congenital rickets associated with magnesium sulfate infusion for tocolysis.

The records of five neonates born to mothers treated with intravenously administered magnesium sulfate for tocolysis were retrospectively reviewed to assess the presence of radiographic, clinical, and biochemical abnormalities. Two infants had radiographic bony abnormalities; one had frank rachitic changes and dental enamel hypoplasia. One of these patients, as well as an additional infant, had transient hypocalcemia. We hypothesize that prolonged infusion of magnesium sulfate, especially when initiated during the second trimester, may lead to fetal parathyroid gland suppression with consequent abnormalities resembling rickets.