(337) Early Response to Treatment of Iron Deficiency Anemia and Association with Perinatal Outcomes

We aimed to determine if initial response to iron therapy was associated with reduced risk of stillbirth and other adverse outcomes in pregnant singletons with moderate iron deficiency anemia (IDA). Iron therapy will first restore hemoglobin and then replete iron stores (ferritin). There is limited data on how repletion of iron/Hb relates to perinatal outcomes.

Study Design:

This is a secondary analysis of a multi-center randomized controlled trial in India comparing single dose intravenous (IV) iron to oral iron for moderate IDA (Hb 7.0-9.9g/dL) at 14-17 weeks gestation. The primary outcome for this analysis was stillbirth. The predictors of interest were maternal hemoglobin and ferritin at 20-24 weeks gestation, after randomization/treatment (14-17 weeks). Secondary outcomes were low birthweight (LBW), small for gestational age infants (SGA), and early preterm birth (PTB)< 34 weeks. Poisson regression with robust standard errors was used to evaluate the relationship between each outcome and the predictors, adjusting for age, BMI, parity, and study site. Two-sided alpha=0.05 used for all analyses.

Results:

4252 participants were included; 1421, 1424, and 1407 randomized to IV ferric derisomaltose, ferric carboxymaltose, and oral iron respectively. There was a progressively reduced risk of stillbirth (p< 0.0001), early PTB (p=0.0009), LBW (p=0.0016), and SGA (p=0.0072) as Hb approached normal range (11.0g/dL) after treatment (Figure). A U-shaped relation was observed with very high Hb trending towards increased risk of adverse outcomes. There was a similar trend between low ferritin and risk of LBW, (p=0.058).

Conclusion:

In pregnancies with moderate IDA, early improvement (20-24 weeks gestation) of hemoglobin to a normal range is associated with reduced rates of stillbirth, LBW, SGA, and early PTB. Very high Hb (≥13) likely reflects pathophysiology of hemoconcentration relating to placental insufficiency, as has been previously reported, rather than over-correction of anemia. Our findings highlight the importance of early identification and early, adequate treatment of IDA in pregnancy