ANN ARBOR, Mich. -

Babies have their own time table, and not all of them arrive as planned. 

New research suggests speeding up that process could come with an unexpected risk.

"We found that moms who were either induced or augmented were more likely to have children who later presented with autism," said Marie Lynn Miranda, senior author of the study and dean of the University of Michigan School of Natural Resources and Environment.

The findings are based on a large, retrospective analysis by researchers at the University of Michigan and Duke Medicine.

The researchers looked at looked at records of all births in North Carolina over an eight-year period and matched 625,042 births with corresponding public school records, which indicated whether children were diagnosed with autism.

They found a 35 percent higher risk of autism in boys whose mothers' labor was induced or augmented.

That's concerning since the Centers for Disease Control and Prevention reports the number of women that are induced each year in the U.S. rose from less than 10 percent to more than 22 percent between 1990 and 2006. 

Inducing labor did not seem to raise the risk of autism for girls, but augmenting labor did. 

"In general, we see higher rates of autism in male children than in female children and we don't really know why," said Miranda.  

One out of every 88 children in the U.S. is diagnosed with an autism spectrum disorder and that number is rising. 

"We don't really know why that disease has been rising over time, and we don't know all the causes of autism, in fact, we don't know many of the causes of autism," said Miranda.  "I really want to emphasize that this is a study that found an association, we didn't find cause and effect at this point." 

Researchers said more extensive studies are needed. 

Experts stressed inducing is often medically necessary for the health of the mom or the baby.  Miranda said, right now, this research won't change that. 

"Your obstetrician is going to have the best information on whether in your particular case induction or augmentation is the right thing to do, so I would follow your obstetrician's advice," said Miranda.