Vitamin A intake and status, and associations with iron status, anaemia, and birth outcomes of pregnant women in the Free State Province, South Africa: The NuEMI study

Abstract

Vitamin A deficiency (VAD) is common among pregnant women (PW) and has been associated with anaemia and adverse birth outcomes. However, in the Free State Province of South Africa, evidence regarding this is limited. Hence, this cross-sectional study investigated the vitA intake and status of PW in Bloemfontein and its association with anaemia, iron status and birth outcomes. Blood was taken from 427 PW to assess status of vitA (retinol-binding protein 4 (RBP4)), iron (ferritin, soluble transferrin receptor), and anaemia (haemoglobin (Hb)). Sociodemographic, HIV, birth outcomes (birth weight and gestational age), and dietary vitA intake data were obtained using a questionnaire in an interview and medical records. Descriptive statistics and linear regression were used to describe variables and association between vitA and iron status and birth outcomes. Median vitA intake was 1007µgRAE/d, with 19% of participants' intake below the EAR of 550µg/d. Median (IQR) RBP4 concentration was 1.51 (0.78) µmol/L. Insufficient vitA and VAD prevalence was 12.2% and 1.2%, respectively. VitA intake was positively associated with RBP4 (β=0.068; 95%CI: 0.020, 0.116; p=0.006). RBP4 was positively associated with Hb (β=0.363; 95%CI: 0.186, 0.539; p <0.001) and ferritin (β=0.359; 95%CI: 0.139, 0.579; p=0.001) but negatively with sTfR (β=-0.125; 95%CI: -0.246, -0.005, p=0.041). No significant association between plasma RBP4 and birth weight, as well as preterm birth was observed. There was a low prevalence of VAD in the study population. Nonetheless, the positive association between RBP4 and Hb, and ferritin highlights the importance of optimal vitA status in preventing maternal anaemia in pregnancy.