Impact of iron‐containing micronutrient supplementation on high hemoglobin concentration during pregnancy

Abstract

ObjectiveWe aimed to examine the impact of prenatal iron‐containing micronutrient supplementation on high hemoglobin (Hb) level during the second trimester and postpartum.MethodsWe conducted a randomized controlled trial among nulliparous Chinese pregnant women with Hb ≥100g/L. Women were enrolled before 20 weeks gestation and randomized to receive daily folic acid (FA), iron + folic acid (IFA), or iron, folic acid, + 13 other micronutrient (MN). Hb was measured at enrollment, 24–28 weeks gestation, and 4–8 weeks postpartum. High Hb was defined as Hb≥132g/L. Of 18,775 women randomized, 13,992 remained in the analysis after excluding 4102 women with baseline Hb ≥132g/L and 681 women without subsequent Hb tests.ResultsBaseline characteristics and adherence did not differ by groups. The rate of high Hb during 24–28 weeks gestation for FA, IFA, and MN group was 5.9%, 5.8%, and 6.4%, respectively; corresponding rate during 4–8 weeks postpartum was 11.9%, 12.3%, and 13.1%, respectively. Compared to FA, the relative risk (95% CI) of high Hb during 24–28 weeks was 0.96 (0.82, 1.13) for IFA and 1.09 (0.93, 1.28) for MN; corresponding relative risk at 4–8 weeks postpartum was 1.03 (0.93, 1.15) and 1.10 (0.99, 1.22).ConclusionCompared with FA, IFA or MN supplementation was not associated with high Hb concentration during pregnancy or postpartum.The study is funded by a cooperative agreement between PUHSC and CDC.Grant Funding Source: Centers for Disease Control and Prevention