Persistent impact of antenatal maternal anaemia on child brain structure at 6–7 years of age: a South African child health study

Background: This study aimed to determine whether associations of antenatal maternal anaemia with smaller corpus callosum, caudate nucleus, and putamen volumes previously described in children at age 2–3 years persisted to age 6–7 years in the Drakenstein Child Health Study (DCHS). Methods: This neuroimaging sub-study was nested within the DCHS, a South African population-based birth cohort. Pregnant women were enrolled (2012–2015) and mother–child dyads were followed prospectively. A sub-group of children had magnetic resonance imaging at 6–7 years of age (2018–2022). Mothers had haemoglobin measurements during pregnancy and a proportion of children were tested postnatally. Maternal anaemia (haemoglobin < 11 g/dL) and child anaemia were classified using WHO and local guidelines. Linear modeling was used to investigate associations between antenatal maternal anaemia status, maternal haemoglobin concentrations, and regional child brain volumes. Models included potential confounders and were conducted with and without child anaemia to assess the relative roles of antenatal versus postnatal anaemia. Results: Overall, 157 children (Mean [SD] age of 75.54 [4.77] months; 84 [53.50%] male) were born to mothers with antenatal haemoglobin data. The prevalence of maternal anaemia during pregnancy was 31.85% (50/157). In adjusted models, maternal anaemia status was associated with smaller volumes of the total corpus callosum (adjusted percentage difference, − 6.77%; p = 0.003), left caudate nucleus (adjusted percentage difference, − 5.98%, p = 0.005), and right caudate nucleus (adjusted percentage difference, − 6.12%; p = 0.003). Continuous maternal haemoglobin was positively associated with total corpus callosum (β = 0.239 [CI 0.10 to 0.38]; p < 0.001) and caudate nucleus (β = 0.165 [CI 0.02 to 0.31]; p = 0.027) volumes. In a sub-group (n = 89) with child haemoglobin data (Mean [SD] age of 76.06 [4.84]), the prevalence of antenatal maternal anaemia and postnatal child anaemia was 38.20% (34/89) and 47.19% (42/89), respectively. There was no association between maternal and child anaemia (χ² = 0.799; p = 0.372), and child anaemia did not contribute to regional brain volume differences associated with maternal anaemia. Conclusions: Associations between maternal anaemia and regional child brain volumes previously reported at 2–3 years of age were consistent and persisted to 6–7 years of age. Findings support the importance of optimising antenatal maternal health and reinforce these brain regions as a future research focus.