I feel tired, pale and dizzy in my second trimester. What's going on?

Q: I'm 19 weeks along and feeling especially tired. I also look paler than usual, and I get dizzy a lot. What's going on?

A: You could have iron-deficiency anemia. This condition affects up to one-third of all pregnant women and is usually harmless, according to Joanna Stone, M.D., associate professor of obstetrics, gynecology and reproductive medicine at Mount Sinai Medical Center in New York. Anemia is caused by an abnormally low concentration of red blood cells. These cells help carry hemoglobin, which in turn transports oxygen throughout the body; this explains why people who are anemic tend to feel fatigued and light-headed. It's normal for hemoglobin levels to drop somewhat during pregnancy, especially during the second trimester, says Stone, a co-author of Pregnancy for Dummies. (Normal levels are 12–14 in nonpregnant women; during pregnancy, it's 11.) Anemia typically doesn't become a real concern until hemoglobin levels drop to six or below. "Levels that low are rare but are linked to a higher incidence of prematurity, miscarriage, low birth weight and intrauterine growth restriction," Stone adds. Most doctors give women a blood test at their first prenatal visit to establish a baseline hemoglobin level; the test is typically repeated at the 20th and 28th weeks or if a woman is feeling particularly fatigued or run-down. It's also routine to give additional iron in the form of prenatal vitamins. If you do become anemic, your doctor will likely prescribe iron supplements as well.