Iron status, anemia, and birth outcomes among pregnant women in urban Bloemfontein, South Africa: the NuEMI study

Abstract

Background: Despite routine iron supplementation for pregnant women in South Africa, anaemia and iron deficiency (ID) in pregnancy remain a public health concern.

Objective: To determine the associations between iron status and birth outcomes of pregnant women attending antenatal clinic at a regional hospital in Bloemfontein.

Methods: In this cross-sectional study of 427 pregnant women, blood was taken to analyze biomarkers of anaemia (haemoglobin), iron status (ferritin and soluble transferrin receptor) and inflammation (C-reactive protein and α-1-acid glycoprotein). A questionnaire was used to collect information about birth outcomes (birth weight and gestational age at birth), HIV exposure, sociodemographics, iron supplement intake, and maternal dietary iron intake using a validated quantified food frequency questionnaire.

Results: The median (Q₁, Q₃) weeks of gestation of participants was 32 (26, 36) at enrolment. Anaemia, iron deficiency (ID), ID anaemia (IDA) and ID erythropoiesis (IDE) were present in 42%, 31%, 19% and 9.8% of participants, respectively. Median (Q₁, Q₃) dietary and supplemental iron intake during pregnancy was 16.8 (12.7, 20.5) mg/d and 65 (65, 65) mg/d, respectively. The median (max-min) total iron intake (diet and supplements) was 81 (8.8-101.8) mg/d, with 88% of participants having a daily intake above the tolerable upper intake level of 45 mg/d. No significant associations of anaemia and iron status with low birth weight and prematurity were observed. However, infants born to participants in the third hemoglobin (Hb) quartile (Hb > 11.3-12.2 g/dL) had a shorter gestation by 1 week than those in the fourth Hb quartile (Hb > 12.2 g/dL) (p = 0.009). Compared to pregnant women without HIV, women with HIV had increased odds of being anaemic (OR:2.14, 95%CI: 1.41, 3.247), having ID (OR:2.19, 95%CI: 1.42, 3.37), IDA (OR:2.23, 95%CI: 1.36, 3.67), IDE (OR:2.22, 95%CI: 1.16, 4.22) and delivering prematurely (OR:2.39, 95%CI: 1.01, 5.64).

Conclusion: In conclusion, anaemia, ID, and IDA were prevalent in this sample of pregnant women, despite the reported intake of prescribed iron supplements, with HIV-infected participants more likely to be iron deficient and anaemic. Research focusing on the best formulation and dosage of iron supplementation to enhance iron absorption and status, and compliance to supplementation is recommended, especially for those living with HIV infection.

Keywords: Anaemia; Birth outcomes; Iron deficiency; Iron deficiency anaemia; Iron deficiency erythropoiesis; Iron supplementation; Pregnancy.