Anaemia at mid-pregnancy is associated with prehypertension in late pregnancy among urban women.

Background: Antenatal iron deficiency and anaemia are associated with gestational hypertension and diabetes mellitus, but so are elevated iron stores and haemoglobin. In South Africa, pregnant women receive routine iron supplementation regardless of iron status.

Aim: This study aimed to assess associations of antenatal iron status and anaemia with blood pressure in pregnant women in urban South Africa. Secondary to this, associations with heart rate, fasting glucose and glucose tolerance were also investigated.

Setting: Johannesburg, South Africa.

Methods: A total of 250 pregnant women, aged 27 (24-32) years, were recruited using consecutive sampling. The authors measured biomarkers of iron status and anaemia at < 18 and ± 22 weeks', blood pressure and heart rate at ± 36 weeks', and fasting glucose and glucose tolerance between 24 and 28 weeks' gestation. Associations were determined using multivariable regression models adjusted for confounders.

Results: The odds of prehypertension in late pregnancy among women with anaemia at ± 22 weeks' gestation were three times higher than among women without anaemia (odds ratio [OR]: 3.01, 95% confidence interval [CI]: 1.22, 7.42). Participants with anaemia at ± 22 weeks' gestation had 2.15 times higher odds of having elevated mean arterial pressure than women without anaemia (OR: 2.15, 95% CI: 1.01, 4.60).

Conclusion: Anaemia at mid-pregnancy could be a predictor of hypertensive disorders in pregnancy. The cause of antenatal anaemia may need further investigation apart from iron deficiency. The effective management of anaemia in pregnant women living in urban South Africa remains a challenge.

Contribution: This study provides evidence about the health impact of pregnant women regarding antenatal supplementation practices in South Africa.