Women who are obese, have diabetes or high blood pressure during pregnancy are significantly more likely to have a child with autism or developmental delays compared to healthy pregnant women of normal weight, according to a new study.
Researchers found that women who were obese during pregnancy were about 67 percent more likely to have autistic children and twice more likely to have other developmental delays compared to normal-weight women.
The U.S. Centers for Disease Control reported last month that women have a one in 88 chance of having an autistic child, but the latest findings suggest that obesity during pregnancy would boost that to a 1 in 53 chance, according to the study authors.
The study, which examines the relationship between high glucose levels during pregnancy and fetus brain development, consisted of 1,004 children aged 2 to 5 years enrolled in the Childhood Autism Risks from Genetics and the Environment study from 2003 to 2010. There were 517 children with autism spectrum disorders, 172 with other developmental disorders and 315 who were development normally.
University of California Davis researchers found that 21.5 percent of mothers of autistic children and 23.8 percent of mothers of children with developmental delays were obese, compared to only 14.3 percent of typically developing children.
Researchers also found that mothers with diabetes were 2.3 times more likely to give birth to a child with developmental delays, and while diabetic mothers were also slightly more likely to give birth to autistic children. The findings showed that 9.3 percent of mothers of autistic children and 11.6 percent of mothers of children with developmental delays had diabetes during pregnancy, while 6.4 percent of mother of normal developing children were autistic. Children with diabetic mothers also scored lower on language and communication tests compared to other children.
Researchers noted that more than 60 percent of women of child-bearing age in the U.S. are overweight, 34 percent are obese, and about 16 percent have a combination of symptoms like high blood pressure, insulin resistance and increased heart disease risk.
"Over a third of U.S. women in their childbearing years are obese and nearly one-tenth have gestational or type II diabetes during pregnancy. Our finding that these maternal conditions may be linked with neurodevelopmental problems in children raises concerns and therefore may have serious public-health implications," Paula Krakowiak, a biostatician at the MIND Institute at the University of California Davis, said in a statement.
Overall 29 percent of the children with autism, 35 percent of the children with another developmental disorder had mother with a metabolic condition during pregnancy, such as diabetes, high blood pressure and obesity, compared to only 19 percent of children in the control group.
While researchers did not prove that the rising autism rate was caused by the nation’s increasing obesity rate, they said that there were apparent parallel increases between the two factors.
"That was definitely one area that I took note of too. I knew obesity rates and diabetes rates were rising, and autism rates were too," Krakowiak told Reuters
Hannah Gardener, an epidemiologist in the Department of Neurology at the University of Miami, told Reuters while a lot is unknown about autism, the latest research will provide scientists more understanding between the link between obesity and the disorder.
Researchers suggest that that because obesity is a significant risk factor for diabetes and hypertension, like the two metabolic conditions, is characterized by increased insulin resistance and chronic inflammation.
Elevated insulin production which requires greater oxygen use may deplete oxygen supply for the fetus or cause fetal iron deficiency, and both these conditions can adversely affect fetal brain development, according to the study authors.
Maternal inflammation, caused by metabolic conditions, can also adversely affect development because proteins involved in cell signaling that are produced by cells of the immune system can cross the placenta and disturb fetal brain development.
Experts say that the latest findings should be enough to encourage expecting mothers to get healthy.
"Even though this association is far from being proven, there is plenty of evidence that obesity and insulin resistance can have health consequence for mothers and fetuses," Gardener told Reuters.
The findings were published on Monday in the journal Pediatrics.