Association between Blood Lead Levels and Anaemia in a Pregnant Population in the Kintampo Area of Ghana: A Prospective Cohort Study

Background: Maternal anaemia and lead exposure both pose substantial risks in pregnancy, but their relationship has not been consistently explored. We assessed trimester-specific blood lead levels (BLLs) and their association with anaemia in pregnant women in the Kintampo area of Ghana. Methods: In this prospective cohort study nested within the PRISMA Maternal and Newborn Health Study in Ghana, 300 pregnant women were enrolled at <14 weeks' gestation and followed until delivery. Trimester-specific venous blood was collected and analysed for haemoglobin levels using Sysmex XN 330 auto analyser (Sysmex Corporation, Japan) and BLL using inductively coupled plasma-mass spectrometry (ICP-MS). Anaemia was defined as 11.0g/dL for first (T1) and third (T3) trimesters and 10.5g/dL for second (T2) trimester according to the World Health Organisation's (WHO's) trimester-specific haemoglobin thresholds and elevated BLL as ≥3.5 µg/dL by the Centers for Disease Control and Prevention (CDC). Multiple logistic regression, adjusted for maternal age, parity, education, malaria parasitaemia, body mass index, gestational age and occupation, examined the BLL and anaemia association. A population-averaged Generalized Estimating Equations (GEE) model was used to assess the association between elevated BLL and anaemia across trimesters. Results: The mean age of participants was 27.7±5.8 years (range 18-44years). Geometric mean BLL increased significantly across trimesters from 1.0 to 1.3 to 1.5 µg/dL (p=0.003) for T1, T2 and T3 respectively. The prevalence of elevated BLL (≥3.5 µg/dL) was 10.7%, 7.6%, and 15.2% for T1, T2, and T3 respectively. Anaemia prevalence increased significantly with increasing trimester from 34.7.0% to 59.3% to 76.0% (p<0.001) for T1, T2 and T3 respectively. In the population-averaged GEE model, elevated BLL was associated with increased odds of anaemia across trimesters, though this did not reach statistical significance (OR = 1.29, 95% CI: 0.77–2.17, p = 0.327). Conclusion: Anaemia prevalence in pregnancy is high in the Kintampo area and increases with advancing gestation. No significant association was observed between BLL and anaemia. These findings reinforce anaemia as a priority for urgent interventions in pregnancy through pathways independent of lead exposure. However, occupational lead surveillance and control remain important policy considerations.