Several of my close friends are, or were, recently pregnant. What I found most curious is how they suddenly became dietitians or nutritionists in their own right, just from being preggers.

I’m convinced that for every pregnant woman, a "new moms' tale" (think "old wives' tale," but younger, hipper, and more widely circulated on the Internet) is born. In addition to the idea that carrying a baby low means it's a boy, or that castor oil induces contractions, most of my friends’ newfound nutrition knowledge is, well, mostly false.

Here are some myths that my girlfriends have come up with recently, and how I set the record straight.

Myth: "I can eat what I want when I'm expecting; it’s the one time I really don’t want to worry about my diet."

Fact: You're no longer "eating for two," as the old statement goes. In fact, calorie requirements don’t even go up in the first trimester. In the second and third trimesters, women need an average of 350 extra calories a day. For most moms-to-be, that should be 2,200 to 2,900 healthy, nutritious calories—not a complete free-for-all.

Myth: "There’s no way to get all the calcium I need naturally while pregnant."

Fact: You need the same amount of calcium during pregnancy and when breast-feeding as you do when you’re not pregnant—1,000 milligrams per day. In fact, when pregnant, your body becomes superefficient at absorbing the mineral. However, since most of us are deficient in calcium before we get pregnant, it is recommended that we take a multivitamin that contains iron, folic acid, calcium, and vitamin D in addition to getting it from food sources. If you can't (or don't) drink milk, get most of your calcium from these nondairy food sources.

Myth: "My doctor says I’m right on target for a 30-pound weight gain."

Fact: The rules regarding pregnancy and weight gain have changed significantly in the past few years because so many women never lose their pregnancy weight gain, putting themselves at risk for obesity. The friend who offered up this piece of knowledge was a little chubby (BMI of 26) before getting pregnant, so her optimal weight gain is actually less than under- or normal-weight women. She should gain, on average, about 20 pounds, not 30. Here are suggestions from the Institute of Medicine guidelines to give you a better idea.

Your BMI
Recommended weight gain

Up to 19.8 28 to 40 lbs.
19.8 to 26 25 to 35 lbs.
26 to 29 15 to 25 lbs.
Greater than 29 At least 15 lbs.
If you're having twins... 35 to 45 lbs.

Next page: Herbal remedies and pregnancy

Myth: "My acupuncturist gave me some great herbs to keep me 'regular' while pregnant."

Fact: Taking herbal remedies or medications while pregnant is generally not recommended, unless your doctor or dietitian gives you the OK.

Myth: "I’d never take the chance of having caffeine while pregnant."

Fact: Research shows that modest amounts of caffeine do not negatively affect pregnancy outcomes. The recommendation is to limit caffeine to no more than 300 milligrams per day. If you can’t live without an a.m. skinny latte, don’t fret. Of course, if you don’t need caffeine, there’s no reason to start up a caffeine habit while pregnant.

Myth: "To be safe, I'm going to avoid exercise when pregnant."

Fact: Exercise is good for most pregnant women. Research shows that exercise can reduce the risk of gestational diabetes by 50% and the risk of dangerous hypertension by 40%. (See illustrations of stretching and strengthening exercises suited for pregnancy.)

Myth: "I'm avoiding all seafood while I'm pregnant, due to toxic mercury levels."

Fact: That’s too bad, I told my gal pal who offered up this gem. Actually, seafood is one of the best sources of lean protein and contains iron, zinc, and many other nutrients important for pregnant women. The recommendations for pregnant women have flip-flopped in recent years, but most agree that it's safe to eat 12 ounces per week of popular options such as shrimp, scallops, salmon, pollack, perch, trout, and light tuna; it may actually be healthy for the brain development of your baby. (Albacore tuna and other higher-mercury fish should be limited to 6 ounces or less per week.)

By Julie Upton, RD

(PHOTO: GETTY IMAGES)