Periodontal exam
What it is: A routine cleaning and examination of your gums by your dentist to keep your teeth and gums healthy and free of infection and disease
What it measures: The connection between teeth and gums and inflammation around your gums
Why you need it: Women who have gum disease have up to a sevenfold higher risk of premature birth. There's also a chance you could simply be more prone to gum disease if you're pregnant or on the Pill. "Hormone changes seem to cause your gums to become more inflamed, although we're not really sure why," says Kimberly Harms, a dentist and a consumer adviser for the American Dental Association.
How often should you have it? Twice a year, but some pregnant women may need to see their doctors every three to four months. "If your gums are bleeding frequently, it's a red flag that you need to go in sooner," says Harms.

Thyroid stimulating hormone (TSH) test
What it is: A blood test that screens for an underactive (hypothyroid) and an overactive (hyperthyroid) thyroid
What it measures: Whether your thyroid hormone levels are normal
Why you need it: "Pregnancy and the postpartum period tend to bring on these conditions," says Dana Simpler, M.D., an internist at Mercy Medical Center, in Baltimore. Still, mild forms of thyroid disease may affect from 5 to 10 percent of all women. It gets worse: More than half of all these cases may remain undiagnosed. Feeling tired, being forgetful, and gaining weight  -- classic symptoms of being a new mom  -- are all signs of hypothyroidism. The opposite condition, hyperthyroidism, usually shows itself with a racing heart, trouble sleeping, or weight loss, which might be dismissed as anxiety or stress.
If you're trying to have another baby, this is a crucial test, since a thyroid disorder can stop you from ovulating and increase your risk of miscarriage or premature delivery. If you're diagnosed with hypothyroidism, you'll be put on a synthetic hormone supplement for life; hyperthyroidism is usually treated with radioactive iodine to reduce thyroid hormone production.
How often should you have it? Once a year.

Complete blood count (CBC)
What it is: A blood test that evaluates how well your bone marrow and immune system are working
What it measures: White blood cells (high levels mean an infection), hemoglobin (low levels indicate anemia), and platelets (low levels signify your blood may have trouble clotting)
Why you need it: You're more likely to have heavy periods after having children, which can make you susceptible to anemia. "Just the other week, I saw a mom who'd been tired and short of breath for months," says Shari Midoneck, M.D., an internist at the Iris Cantor Women's Health Center, in New York City. "We ran blood tests, and she was severely anemic. I put her on iron supplements immediately, and after a week she said she couldn't believe how much better she felt."
How often should you have it? Every year.