AMERICAN WOMEN are heavier than ever before, which means many are entering pregnancy overweight or obese. More than cosmetic, gaining too much weight during pregnancy can put mother and baby's health at risk.

That's why the Institute of Medicine last week released new guidelines - for the first time in 20 years - on how much a woman should gain during pregnancy. The guidelines were developed by the World Health Organization and adopted by the National Heart, Lung, and Blood Institute.

Simply put, women who are obese (as classified by their Body Mass Index, or BMI*) should gain 11 to 20 pounds; overweight women, 15-25 pounds; normal-weight women, 25-35 pounds; and underweight women, 28-40 pounds.

That's for your entire pregnancy - not the first trimester!

The new recommendations are mostly the same as they were in 1990, except that a classification has been made for obese women. And they could not have come a moment to soon.

From the heart, I am sick and tired of seeing family and friends suffer needlessly from the health consequences of carrying too much weight before, during and after pregnancy. I know three women who during their recent pregnancies ended up with serious health problems such as gestational diabetes, preeclampsia and, in one case, even a heart attack.

The two things these women had in common was that they were either overweight or obese when they got pregnant, and each gained too much weight during her pregnancy.

My friend Tyeshia, who gained 25 pounds in her first trimester, insisted on a daily date at McDonald's for a large vanilla shake. She claimed she needed it for the "calcium" - though I informed her that the shakes had more empty calories than calcium.

Sorry, if I'm a killjoy. But there's nothing but chemicals and empty calories - a whopping 1,110 calories - in McDonald's 32-ounce triple vanilla shake. It also has 193 carbs, 26 grams of fat and 145 grams of sugar. Good stuff for a growing fetus and a pregnant mom, right?

You know the answer to that is a big, fat NO!

By consuming that shake, she was taking in almost four times the amount of extra calories a pregnant woman needs every day. That's right, a woman of normal weight needs only about an extra 300 calories a day to support a pregnancy.

What does an extra "quality" 300 calories look like?

One piece of whole wheat toast with one tablespoon of peanut butter, plus an 8-ounce glass of low-fat milk. Or, three glasses of skim milk would also meet the requirement.

The bottom line is that too many women look at pregnancy as a time to pig out. Not only do you need just an extra 300 calories, but those calories need to be from quality, wholesome foods.

Tyeshia found out the hard way when she was diagnosed with gestational diabetes, the only thing that liberated her from her glorious misperceptions about pregnancy and weight gain.

Unfortunately, gestational diabetes doesn't just affect the mother's health. A fetus exposed to gestational diabetes is at increased risk of complications that include macrosomia (large baby), birth trauma, hypoglycemia (low-blood sugar), jaundice and, though rare, even death.

Thankfully, in Tyeshia's case, everything worked out; she and her baby are now healthy. But she learned an important lesson and no longer takes her good health for granted.

If this column hit a raw nerve with you, it was meant to. We Americans like to pay lip service to health issues, but we really don't like wrestling with our national weight problem. We dig our heads in the sand and wait for the next quick fix, instead of rolling up our sleeves to do the real work we know is required.

What is more precious than good health? Nothing trumps it - not cash, not cars, not clothes or bling. At the minimum, let's give good health to our babies.

* Don't know your BMI? Here's an online calculator from the National Institutes of Health: www.nhlbisupport.com/bmi. *

Kimberly Garrison is a certified personal trainer and owner of One on One Ultimate Fitness in Philadelphia (www.1on1ultimatefitness.com). E-mail her at kimberly@1on1ultimatefitness.com. Her column appears each Thursday in Yo!