RESEARCH – February 2021

Anaemia and iron supplement usage in pregnancy: association with pregnancy complications

Authors: Karina Luik, Kristiina Rull

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Objectives. The aim of the study was to assess the prevalence of anaemia and anaemia-related complications during the pregnancy and to address the association between iron supplementation and pregnancy complications.

Methods. A prospective cohort study „Happy Pregnancy recruited 2334 pregnant women at their first antenatal visit to the Women’s Clinic, Tartu University Hospital, in 2013–2015. Data about the course and outcome of pregnancy was obtained from medical records and data about iron supplemention was obtained from three questionnaires filled in by the pregnant women in each trimester. Anaemia was defined by haemoglobin level <110 g/l in the first and third trimesters, and <105 g/l in the second trimester.

Results. The prevalence of anaemia was 4.2% in the first, 9.9% in the second, and 31.9% in the third trimester. Anaemia occurred more frequently among women with a restricted diet, lower body mass index, younger age and twin pregnancy. Anaemia in the first trimester increased the risk for pregnancy loss (OR 3.1 [95% CI 1.3–7.5]), in the second trimester, for preterm delivery (OR 2.3 [1.4–3.9]), in the third trimester, for preeclampsia (OR 2.3 [1.3–4.0]), birth of a newborn small for gestational age (OR 1.6 [1.3–2.5]), postpartum haemorrhage (OR 1.8 [1.4–2.4]), and blood transfusion after delivery (OR 3.8 [2.1–6.6]). Iron supplements were used by 3.3%, 11.3% and 25.9% of the pregnant women in the first, second and third trimester, respectively. Among the women with anaemia, iron replacement therapy in the third trimester reduced the risk of preeclampsia (1.1%, versus 6.2%, OR 0.2 [0.01–0.6]) and the rate of caesarean section (14.7 % versus 22.4%, OR 0.6 [0.4–0.9]). Among women without anaemia, iron replacement therapy had no effect on any pregnancy complication.

Conclusions. Anaemia in pregnancy increases the risk for pregnancy loss, preterm birth, preeclampsia, birth of a newborn small for gestational age, and postpartum haemorrhage. Iron supplements reduce the risk for preeclampsia and the rate of cesarean section only among pregnant women with anaemia.