Around 1900, the average weight of a 5 foot, 3 inch American woman ages 25 to 29 was 132 pounds.

Today, according to a new report, 50 percent of moms-to-be (average height 5 foot, 4 inches) are overweight (25.6 percent) or obese (24.8 percent) before becoming pregnant.

That can cause troubles such as gestational diabetes and pre-eclampsia during pregnancy; a tougher delivery; and diabetes, depression, and heart woes after giving birth.

It can also increase a child's risk of premature diabetes, obesity, and other health challenges down the road.

And now there's another wrinkle: Researchers found that if Mom eats a high-fat diet while pregnant, baby's gut biome ends up with a lack of Bacteroides microbes, which are essential for extracting energy from carbohydrates and nurture other important gut bacteria.

The result? A baby can end up with a compromised immune system and compromised metabolic health.

So moms-to-be, make sure you take prenatal vitamins with DHA-omega-3.

They reduce the risk of autism spectrum disorder by 40 percent and spine malformation and childhood cancer by over 60 percent.

And keep close tabs on your unhealthy fat intake: Eliminate all trans fats and most saturated fat; stick with skinless poultry and fish.

Limit fat intake to no more than about 25 percent of daily calories; if you're eating 1,800 calories a day, that means 350 should come from healthy fats, just a bit less than 3 tablespoon of olive oil.