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.

Next page: Herbal remedies and pregnancy