Iron status markers during pregnancy. No relationship between levels at the beginning of the second trimester, prior to delivery and post partum

Abstract

Objective: To evaluate whether levels of iron status markers (haemoglobin, serum transferrin saturation, serum ferritin) in pregnant women, measured in the beginning of the second trimester, could be used to predict levels later in pregnancy, pre partum and post partum.

Design: Randomized, double-blind, placebo-controlled parallel study.

Setting: The Birth Clinic at the Department of Obstetrics, Herning Hospital, Herning, Denmark.

Subjects: One hundred and twenty healthy pregnant women between 14 and 18 weeks of gestation.

Interventions: Sixty-three women were allocated to treatment with tablets containing 66 mg ferrous iron (as fumarate) daily, and 57 women to treatment with placebo.

Main outcome measures: Haemoglobin, serum transferrin saturation, and serum ferritin were measured every 4th week during gestation, prior to delivery, and 1 and 8 weeks post partum.

Results: Correlation matrices during pregnancy and post partum were calculated for each iron status marker separately in iron-treated and placebo-treated women. Haemoglobin, transferrin saturation and serum ferritin values at inclusion displayed steadily declining correlation coefficients with values obtained later in pregnancy. There were no clinically relevant correlations to values obtained 8 weeks or less prior to delivery, and no correlations to values post partum. Serum ferritin values at inclusion could not be used to predict values later in pregnancy or post partum.

Conclusion: Haemoglobin, transferrin saturation and serum ferritin values measured in the beginning of the second trimester appear to be unsuitable as guidelines for an individual iron prophylaxis in pregnant women.