Maternal Obesity May Increase Child's Risk for Cerebral Palsy

Nicola M. Parry, DVM

March 07, 2017

Among Swedish women, being overweight or obese in early pregnancy is associated with a greater risk of giving birth to a child with cerebral palsy, a new study shows.

Eduardo Villamor, MD, DrPH, from the University of Michigan, Ann Arbor, and colleagues published the results of their study online March 7 in JAMA.

"In this nationwide Swedish study, maternal overweight and increasing grades of obesity were associated with increasing rates of cerebral palsy," the authors write.

"The association was restricted to children born at full term and was partly mediated through asphyxia-related neonatal complications."

Despite improvements in perinatal care, an increasing prevalence of cerebral palsy has been reported from 1998 through 2006 among children born at full term. Whereas maternal obesity is a significant risk factor for obstetric complications and asphyxia-related neonatal morbidities, it has been unclear if it is a risk factor for cerebral palsy in the offspring.

Dr Villamor and colleagues therefore investigated the relationship between maternal obesity in early pregnancy and risk for cerebral palsy in the offspring, as well as possible mechanisms for any such association.

They performed a nationwide retrospective cohort study of 1,423,929 singleton births by using data recorded in the Swedish Medical Birth Register from 1997 through 2011. They also used national registries to follow the children for a cerebral palsy diagnosis through 2012.

Overall, 3029 of the children were diagnosed with cerebral palsy over a median 7.8 years of follow-up.

The authors also found that maternal overweight (body mass index [BMI] of 25 to 29.9) and increasing grades of obesity (BMI 30 or greater) in early pregnancy were associated with increasing rates of cerebral palsy in the offspring. This association was statistically significant only for children born at full term, who accounted for 71% of all children with cerebral palsy, the authors say.

Compared with children born to mothers of normal weight, the adjusted hazard ratios (aHRs) for cerebral palsy were 1.22 (95% confidence interval [CI], 1.11 - 1.33) for mothers who were overweight, 1.28 (95% CI, 1.11 - 1.47) for those with grade 1 obesity, 1.54 (95% CI, 1.24 - 1.93) for those with grade 2 obesity, and 2.02 (95% CI, 1.46 - 2.79) for those with grade 3 obesity.

The authors' analyses also showed that birth asphyxia–related neonatal complications mediated approximately 45% of the association between maternal BMI and rates of cerebral palsy in full-term children. Other mediating factors included low Apgar score (30%), instrumental delivery (17%), and nervous system malformations (13%).

Although the effect of maternal obesity on cerebral palsy risk may seem small compared with other risk factors, the authors highlight its relevance by emphasizing the rising obesity rates. In the United States alone, approximately half of all pregnant women attending their first prenatal appointment are overweight or obese, they say.

"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," Dr Villamor and colleagues conclude.

This study was funded by a grant from the Swedish Research Council for Health, Working Life, and Welfare and an unrestricted grant from Karolinska Institutet. One author has reported being a board member for Itrim and receiving grant funding from the National Institutes of Health for research comparing bariatric surgery and nonsurgical treatment for weight loss. The remaining authors have disclosed no relevant financial relationships.

JAMA. Published online March 7, 2017. Abstract

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