Similar relations were observed in women from rural Nepal, in whom anemia with iron deficiency in the first or second trimester was associated with a 1.87-fold higher risk of preterm birth, but anemia alone was not. (21). In an analysis of 3728 deliveries in Singapore, 571 women who were anemic at the time of delivery had a higher incidence of preterm delivery than did those who were not anemic, but no other differences in either pregnancy complications or neonatal outcomes were observed (29). Thus, the results of several studies are consistent with an association between maternal iron deficiency anemia in early pregnancy and a greater risk of preterm delivery. The apparent loss of this association in the third trimester is probably because a higher hemoglobin concentration at this time may reflect poor plasma volume expansion and an inability to discriminate between low hemoglobin caused by iron deficiency from that caused by plasma volume expansion.