While some of that spike may be due to better methods for detecting the disorder, experts say there could be environmental factors at play.
A new study of one thousand mothers and their children finds that women who are obese during pregnancy are sixty percent more likely to have a child with autism -- and two times more likely to have a child with a developmental delay.
Having Type 2 diabetes, a condition often linked to obesity, also increases the risk.
The researchers say conditions that cause a spike in insulin can starve the mothers tissues of oxygen which lowers the oxygen supply to their unborn child and potentially affecting its brain development.
The study found children without autism whose mothers were obese or diabetic during pregnancy also had deficits in problem solving and language though not as severe as those diagnosed with a developmental disorder.