A new effect of intravenous iron treatment in pregnancy: contraction in nonstress test and timing of labor.

In pregnant women with iron deficiency anemia who were beyond 35 weeks, temporary regular contractions may be observed in the nonstress test following intravenous iron replacement. We think that this effect may lead to early term birth in pregnant women with a history of cesarean section. It needs to be confirmed by further prospective studies and animal studies.