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    Original Investigation
    September 18, 2019

    Association of Prenatal Maternal Anemia With Neurodevelopmental Disorders

    Author Affiliations
    • 1Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
    • 2Centre for Epidemiology and Community Medicine, Stockholm County Council, Stockholm, Sweden
    • 3Department of Epidemiology and Biostatistics, Drexel University Dornsife School of Public Health, Philadelphia, Pennsylvania
    • 4A. J. Drexel Autism Institute, Philadelphia, Pennsylvania
    • 5Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
    JAMA Psychiatry. Published online September 18, 2019. doi:https://doi.org/10.1001/jamapsychiatry.2019.2309
    Key Points

    Question  Is maternal anemia during pregnancy associated with risk of 3 commonly co-occurring neurodevelopmental disorders: autism spectrum disorder, attention-deficit/hyperactivity disorder, and intellectual disability?

    Findings  In this cohort study of 532 232 nonadoptive Swedish children and their 299 768 mothers, anemia diagnosed earlier in pregnancy (≤30 weeks) was significantly associated with increased offspring risk of autism spectrum disorder, attention-deficit/hyperactivity disorder, and intellectual disability. These associations were not apparent for anemia diagnosed later in pregnancy.

    Meaning  The findings suggest that maternal anemia occurring during early pregnancy is associated with increased risk for autism spectrum disorder, attention-deficit/hyperactivity disorder, and in particular, intellectual disability, emphasizing the importance of early screening for iron status and nutritional counseling in antenatal care.


    Importance  Given the critical role that iron plays in neurodevelopment, an association between prenatal iron deficiency and later risk of neurodevelopmental disorders, such as autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and intellectual disability (ID), is plausible.

    Objective  To test the a priori hypothesis that anemia diagnosed in mothers during pregnancy is associated with an increased risk of ASD, ADHD, and ID in offspring and that the magnitude of the risk varies with regard to the timing of anemia in pregnancy.

    Design, Setting, and Participants  This cohort study used health and population register data from the Stockholm Youth Cohort to evaluate 532 232 nonadoptive children born from January 1, 1987, to December 31, 2010, in Sweden, with follow-up in health registers until December 31, 2016. Data analysis was performed from January 15, 2018, to June 20, 2018.

    Exposures  Registered diagnoses of anemia during pregnancy. Gestational timing of the first recorded anemia diagnosis (≤30 weeks or >30 weeks) was considered to assess potential critical windows of development.

    Main Outcomes and Measures  Registered diagnoses of ASD, ADHD, or ID or co-occurring combinations of these disorders.

    Results  The cohort included 532 232 individuals (272 884 [51.3%] male) between 6 and 29 years of age at the end of follow-up (mean [SD] age, 17.6 [7.1] years) and their 299 768 mothers. The prevalence of ASD, ADHD, and ID was higher among children born to mothers diagnosed with anemia within the first 30 weeks of pregnancy (4.9% ASD, 9.3% ADHD, and 3.1% ID) compared with mothers with anemia diagnosed later in pregnancy (3.8% ASD, 7.2% ADHD, and 1.1% ID) or mothers not diagnosed with anemia (3.5% ASD, 7.1% ADHD, and 1.3% ID). Anemia diagnosed during the first 30 weeks of pregnancy but not later was associated with increased risk of diagnosis of ASD (odds ratio [OR], 1.44; 95% CI, 1.13-1.84), ADHD (OR, 1.37; 95% CI, 1.14-1.64), and ID (OR, 2.20; 95% CI, 1.61-3.01) in offspring in models that included socioeconomic, maternal, and pregnancy-related factors. Early anemia diagnosis was similarly associated with risk of ASD (OR, 2.25; 95% CI, 1.24-4.11) and ID (OR, 2.59; 95% CI, 1.08-6.22) in a matched sibling comparison. Considering mutually exclusive diagnostic groups, we observed the strongest association between anemia and ID without co-occurring ASD (OR, 2.72; 95% CI, 1.84-4.01). Associations of these disorders with anemia diagnosed later in pregnancy were greatly diminished.

    Conclusions and Relevance  In contrast to maternal anemia diagnosed toward the end of pregnancy, anemia diagnosed earlier in pregnancy was associated with increased risk of the development of ASD, ADHD, and particularly ID in offspring. Given that iron deficiency and anemia are common among women of childbearing age, our findings emphasize the importance of early screening for iron status and nutritional counseling in antenatal care.