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Maternal overweight, obesity associated with increased rate of cerebral palsy

Swedish women with overweight or obesity during pregnancy had a significantly increased risk for delivering a full-term child with cerebral palsy; this risk was partially mediated by asphyxia-related neonatal complications, according to research published in JAMA.

“Despite advances in obstetric and neonatal care, cerebral palsy prevalence increased from 1998 through 2006 in children born at full term,” Eduardo Villamor, MD, DrPH, of the department of epidemiology at the University of Michigan School of Public Health, and colleagues wrote.

“Maternal overweight and obesity are associated with increased risks of preterm delivery, asphyxia-related neonatal complications, and congenital malformations, which in turn are associated with increased risks of cerebral palsy,” they added. “It is uncertain whether risk of cerebral palsy in offspring increases with maternal overweight and obesity severity and what could be possible mechanisms.”

Villamor and colleagues conducted a population-based retrospective cohort study to determine the associations between early pregnancy BMI and rates of cerebral palsy in offspring. They also sought to identify mediators of these associations. The analysis included 1,423,929 singleton children (mean gestational age, 39.8 weeks; 51.4% male) born in Sweden from 1997 to 2011. The children were followed through 2012 for a cerebral palsy diagnosis based on national registry data. The researchers categorized BMI as underweight (< 18.5 kg/m²), normal weight (18.5 to 24.9 kg/m²), overweight (25 to 29.9 kg/m²), obesity grade 1 (30 to 34.9 kg/m²), obesity grade 2 (35 to 39.9 kg/m²) or obesity grade 3 ( 40 kg/m²).

Over a median of 7.8 years of follow-up, 3,029 children were diagnosed with cerebral palsy (risk, 2.13 per 1,000 live births; rate, 2.63/10,000 child-years). A total of 2.4% of mothers were underweight, 61.8% were normal weight, 24.8% were overweight, 7.8% were obesity grade 1, 2.4% were obesity grade 2 and 0.8% were obesity grade 3. The researchers identified 64 cases of cerebral palsy for offspring of mothers in the underweight category, 1,487 cases in the normal weight category, 728 cases in the overweight category, 239 cases in the obesity grade 1 category, 88 cases in the obesity grade 2 category and 38 in the obesity grade 3 category, with rates per 10,000 child-years of 2.58, 2.35, 2.92, 3.15, 4.0 and 5.19, respectively. Adjusted HRs of cerebral palsy were 1.22 (95% CI, 1.11-1.33) for overweight, 1.28 (95% CI, 1.11-1.47) for obesity grade 1, 1.54 (95% CI, 1.24-1.93) for obesity grade 2, and 2.02 (95% CI, 1.46-2.79) for obesity grade 3, in comparison to children born to mothers of in the normal weight category.

The researchers noted that these findings were statistically significant for full-term infants (71% of all children with cerebral palsy), but not preterm infants. Asphyxia-related neonatal morbidity mediated approximately 45% of the linkage between maternal BMI and rates of cerebral palsy in full-term children, according to Villamor and colleagues.

While the study contained many strengths, there were also some limitations, including potential selection bias due to missing BMI data or important covariates for 10% of women, misclassification of some cerebral palsy subtypes and using a relatively homogenous population, they wrote.

“Although the effect of maternal obesity on cerebral palsy may seem small compared with other risk factors, the association is of public health relevance due to the large proportion of women with overweight or obesity worldwide,” Villamor and colleagues concluded. “The number of women with a BMI of 35 kg/m² or more globally doubled from approximately 50 to 100 million from 2000 through 2010. In the United States, approximately half of all pregnant women have overweight or obesity at the first prenatal visit. Considering the high prevalence of obesity and the continued rise of its most severe forms, the finding that maternal overweight and obesity are related to rates of cerebral palsy in a dose-response manner may have serious public health implications.” – by Alaina Tedesco

Disclosure: The researchers report receiving supported from a grant from the Swedish Research Council for Health, Working Life, and Welfare and an unrestricted grant from Karolinska Institutet.