Changes in Maternal Hemoglobin Concentration and Risk of Low Birth Weight and Small-for-Gestational-Age in the United...

Maternal hemoglobin (Hb) concentration and changes in Hb across trimesters have been linked to low birth weight (LBW) and small-for-gestational-age (SGA). However, these associations have shown inconsistent results and have not been investigated in pregnant women in the United Arab Emirates (UAE). We investigated the association between changes in Hb concentration during the first and second trimesters and birth weight, LBW, and SGA among pregnant women in the UAE.

We utilized data from the Mutaba'ah Study. Change in Hb was computed as the difference between the first and second trimester Hb concentrations. LBW and SGA were defined as birth weight below 2500 grams and birth weight below the 10th percentile, respectively. Multivariable regression models were used to investigate the association between changes in maternal Hb and birth weight, LBW and SGA.

A total of 1500 pregnant women were included. The mean maternal age was 32 years (SD 6). Overall, Hb concentration declined from the first to the second trimesters by a median of -9 g/L (IQR: -14, -3). LBW and SGA were observed among 6% and 10% of the newborns, respectively. Pregnant women who experienced the least reduction or an increase in Hb concentration had a higher risk of both LBW (adjusted odds ratio [aOR]: 3.43, 95% confidence interval [CI]: 1.77 to 6.96) and SGA (aOR: 2.08, 95% CI: 1.28 to 3.40) compared to those with the greatest reduction in Hb concentration.

Minimal reductions in Hb levels from the first to the second trimester were associated with LBW and SGA. The average Hb levels during the second trimester were inversely associated with birth weight and SGA. Monitoring variations in maternal Hb early in pregnancy may enhance the early identification of pregnancies at risk.