Anaemia and Maternal Iron Intakes in Pregnancy and Child Asthma: An Observational Analysis From a Longitudinal Cohort

ABSTRACT Background and Aims Evidence supporting the association between anaemia and lower iron intakes during pregnancy with an increased risk of childhood asthma remains unclear. This study aimed to investigate whether (i) lower haemoglobin or anaemia in late pregnancy and (ii) lower mean dietary iron intake in pregnancy were associated with a higher risk of childhood asthma. We hypothesised that lower maternal haemoglobin concentrations or anaemia, and lower mean dietary iron intakes, during pregnancy are associated with an increased risk of childhood asthma. Methods This is a longitudinal study of mother‐child dyads (n = 474) who participated in the ROLO (Randomised cOntrol trial of a LOw glycaemic index diet in pregnancy to prevent macrosomia) trial between 2007 and 2022. Healthy women were recruited in early pregnancy and randomised to receive low glycaemic index dietary advice or routine care. Haemoglobin concentrations were measured in late pregnancy and anaemia was defined as < 11 g/dL. Maternal iron intakes were estimated from 3‐day food diaries during pregnancy. Mothers reported whether their children had current doctor‐diagnosed asthma at 5 and 9–11 years of age. Multivariable logistic regression models examined the associations of haemoglobin concentrations or anaemia in late pregnancy, and mean dietary iron intakes during pregnancy, with asthma outcomes. Results In late pregnancy, the median (IQR) haemoglobin concentration was 11.7 (11.0, 12.2) g/dL and 21% (n = 95) of women were anaemic. The median (IQR) dietary iron intake in pregnancy was lower than recommended at 10.9 (9.3, 13.1) mg/day. The prevalence of current‐doctor diagnosed asthma at 5 and 9–11 years of age was 7% and 7.7%, respectively. Maternal haemoglobin concentrations or anaemia in late pregnancy, and mean maternal dietary iron intakes during pregnancy, were not associated with childhood asthma at either age. Conclusion Maternal anaemia and low dietary iron intake were not associated with childhood asthma in this longitudinal study.