A group of Spanish researchers investigated the relationships between maternal iron deficiency and maternal obesity on children’s neurodevelopment.

Requirements for fetal and maternal iron are high, and iron deficiency (ID) is a common pregnancy-related condition. Research has shown that iron plays a key role in neurodevelopment among prenatal and perinatal infants. While low-birth-weight babies and other groups, such as babies born to diabetic mothers, may be at risk of iron deficiency, the relationship between maternal iron deficiency and iron deficiency in offspring has not been well studied. Babies born to overweight or obese mothers or mothers with gestational diabetes (GD) may also be at risk for sub-optimal neurodevelopment, and obesity is a risk factor for maternal iron deficiency. Previous research has suggested that babies born to obese mothers may have reduced iron stores, suggesting a potential mechanism through which obesity influences neurodevelopment.

A group of Spanish researchers has been studying the influence of weight and gestational diabetes on prenatal and postnatal neurodevelopment compared to healthy weight controls in a prospective observational study. They have observed an association between obesity and maternal iron deficiency, and they have also found differences in neurodevelopment in babies born to overweight mothers. They conducted a study recently published in the British Journal of Nutrition to investigate the independent associations of maternal iron deficiency and weight with neurodevelopment at 18 months of age.

Recruiting Mothers with Gestational Diabetes

The researchers recruited 331 pregnant women between 2008 and 2012 at two hospitals in Granada, Spain. Of these, 166 women were either overweight or obese, and the remainder had a normal pre-gestational body mass index (BMI). The researchers actively recruited mothers with gestational diabetes in all three BMI categories; 46 mothers in the overweight group and 33 in the normal weight group had diabetes. The mothers who were included in the study participated in routine medical care during data collection.

Assessing Maternal Iron Status

The researchers collected sociodemographic data and data on iron supplementation. Maternal iron status was assessed at 34 weeks of gestation and at delivery. Infant neurodevelopment was assessed at 18 months using the Bayley Scales of Infant Development. The scales measure five domains that include cognitive skills, receptive language, expressive language, fine motor development, and gross motor development. Between birth and 18 months, 109 participants dropped out of the study, leaving 194 children with Bayley assessments. Data on iron status at 34 weeks of gestation and at delivery was not available for all mothers with children who had Bayley scores.

First, the researchers compared the 18-month Bayley scores of offspring whose mothers were iron deficient at 34 weeks and at delivery with the scores of offspring whose mothers were non-iron deficient. The results showed that composite motor scores were significantly lower among offspring whose mothers were iron deficient at 34 weeks. In addition, mothers with iron deficiency at delivery had offspring with lower cognitive scores and lower receptive, expressive and composite language scores at 18 months. The researchers accounted for gestational diabetes and weight in all analyses, and associations remained.

Next, the researchers examined the effect of BMI on Bayley scores after accounting for maternal iron status and other potential confounding influences (e.g., sex, gestational age at birth, and maternal educational level). They compared the scores of offspring born to overweight or obese mothers to the scores of offspring of normal weight mothers. Gross motor scores were lower in the overweight/obese group compared to the normal weight group.

Maternal Iron Deficiency Negatively Impacts Neurodevelopment

Overall, the results of this study suggest that maternal iron deficiency late in pregnancy negatively impacts neurodevelopment, including language, motor, and cognitive development at 18 months of age. Additionally, maternal overweight or obesity was associated with impairments in gross motor development based on Bayley scores at 18 months.

Maternal iron deficiency and obesity together may increase the risk of poor neurodevelopment in offspring. While the study was limited by its observational design, the researchers controlled for other factors that have been associated with poor neurodevelopment in previous research, and they collected both mother and infant data.  Because maternal iron deficiency is a common condition, further research is needed to determine more precise requirements for iron at different stages of neurodevelopment and to support prevention and intervention trials to mitigate the risks associated with iron deficiency and obesity.

Written by Suzanne M. Robertson, Ph.D.

Reference: Berglund, S. K., Torres-Espínola, F. J., García-Valdés, L., Segura, M. T., Martínez-Zaldívar, C., Padilla, C., … & Campoy, C. (2017). The impacts of maternal iron deficiency and being overweight during pregnancy on neurodevelopment of the offspring. British Journal of Nutrition, 1-8.

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