Sarah Jessica Parker did it. So did Gwyneth Paltrow. Pregnancy inspired them to get healthier.

In a nutshell, they focused on regimens like the Mediterranean diet — whole grains, no processed foods (fish and lean meats for Ms. Parker; Ms. Paltrow is a strict vegan), low-carb veggies, and lots of fruit.

Clearly, they know how important it is for moms-to-be to be healthy in order to have healthy kids.

Recently, researchers from Johns Hopkins came to the same conclusion. They found that the offspring of mothers who were obese and had diabetes before they conceived or developed gestational diabetes were four times more likely to be diagnosed with autism spectrum disorder than children of normal-weight, diabetes-free moms.

Finally, one reasonable theory about why this developmental handicap is so widespread today.

Here are the facts:

• Cases of autism among U.S. kids have increased from 1 in 150 in 2000 to 1 in 68 in 2010. That's up 119.4 percent.

•In 1983, 24 percent of newly pregnant women were overweight or obese. In 2015, it was 45 percent — almost a 100 percent increase.

• From 1987 to 2007 the incidence of gestational diabetes increased 100 percent.

This doesn't mean thin, nondiabetic women can't have offspring with this condition, it just means obesity and diabetes increase the risk fourfold.