Impact of high maternal hemoglobin at first antenatal visit on pregnancy outcomes: a cohort study

To determine whether high maternal hemoglobin (Hb) at first antenatal visit is associated with adverse pregnancy outcomes.

A retrospective cohort study was conducted in 920 singleton pregnancies who started their antenatal booking in the first trimester (125 g/L) were matched 1:1 with those who had normal Hb values (110-124 g/L) according to age group and parity. Adverse pregnancy outcomes including preeclampsia, gestational diabetes mellitus (GDM), preterm delivery, low birth weight (LBW), and small for gestational age (SGA) infants between both groups were compared.

Complete obstetric records of 426 and 448 women who had high and normal Hb levels, respectively, were studied. By uni- and multivariable analyses, women with high Hb levels had significantly higher rates of preeclampsia and GDM than those with normal Hb levels; their adjusted relative risks were 3.8 (95% confidence interval [CI]; 2.0, 7.1) and 3.3 (95% CI; 1.8, 6.0), respectively. Rates of preterm delivery, low birth weight, and small for gestational age infants between the two groups were not significantly different.

Our findings suggest that high Hb in the first trimester is associated with subsequent preeclampsia and GDM.