Maternal anemia and neurodevelopmental disorders in children
Some experts, but not all, believe that iron deficiency during pregnancy may adversely impact fetal neurodevelopment and result in childhood behavior issues. All experts agree that more research is needed to understand if maternal anemia causes mental health issues in newborns. In one meta-analysis, among 20 studies of the association of maternal iron deficiency and newborn neurodevelopment, approximately half the studies reported that low maternal ferritin levels were associated with lower childhood performance on standardized tests of cognitive, motor, verbal, and memory function.19 Another systematic review concluded that the evidence linking maternal iron deficiency and child neurodevelopment is equivocal.20
In a study of 532,232 nonadoptive children born in Sweden from 1987 to 2010, maternal anemia was associated with an increased risk of autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and intellectual disability (ID).21 In Sweden maternal hemoglobin concentration is measured at 10, 25, and 37 weeks of gestation, permitting comparisons of anemia diagnosed early and late in pregnancy with neurodevelopmental outcomes. The association between anemia and neurodevelopmental disorders was greatest if anemia was diagnosed within the first 30 weeks of pregnancy. Compared with mothers without anemia, maternal anemia diagnosed within the first 30 weeks of pregnancy was associated with higher childhood rates of ASD (4.9% vs 3.5%), ADHD (9.3% vs 7.1%), and ID (3.1% vs 1.3%).21 The differences persisted in analyses that controlled for socioeconomic, maternal, and pregnancy-related factors. In a matched sibling comparison, the diagnosis of maternal anemia within the first 30 weeks of gestation was associated with an increased risk of ASD (OR, 2.25; 95% CI, 1.24-4.11) and ID (OR, 2.59; 95% CI, 1.08-6.22) but not ADHD.21 Other studies have also reported a relationship between maternal anemia and intellectual disability.22,23
Measurement of hemoglobin will identify anemia, but hemoglobin measurement is not sufficiently sensitive to identify most cases of iron deficiency. Measuring ferritin can help to identify cases of iron deficiency before the onset of anemia, permitting early treatment of the nutrient deficiency. In pregnancy, iron deficiency is the prelude to developing anemia. Waiting until anemia occurs to diagnose and treat iron deficiency is suboptimal and may miss a critical window of fetal development that is dependent on maternal iron stores. During pregnancy, ferritin levels decrease as much as 80% between the first and third trimesters, as the fetus utilizes maternal iron stores for its growth.24 We recommend the measurement of ferritin and hemoglobin at the first prenatal visit and again at 24 to 28 weeks’ gestation to optimize early detection and treatment of iron deficiency and reduce the frequency of anemia prior to birth. ●