We all know about the importance of prenatal medical care in assuring the health of a pregnant woman and her baby. But many experts now recommend that women start seeing an obstetrician before they become pregnant for something called pre-pregnancy or preconception care.

It may seem excessive -- after all, why start worrying before you're pregnant? But a doctor can really help even at an early stage. He or she can run tests to make sure that you and your partner don't have any hidden illnesses that could affect your pregnancy or your chances of becoming pregnant. Your doctor can also give you advice about exercise , eating, and lifestyle. Some studies show that preconception care can increase your chances of becoming pregnant and reduce the risks of miscarriage or birth defects .

Getting Your Checkup

Your doctor will want to start by getting a full medical history from both you and your partner. He or she will also want to run a number of tests -- such as blood tests and a Pap smear -- to make sure that neither of you have any medical conditions that could affect pregnancy or your chances of conceiving. Your doctor might test for illnesses such as:

• Rubella, or German measles
• Chickenpox
• HIV
• Hepatitis B
• Herpes
• Other STDs (such as chlamydia, syphilis, and gonorrhea)
• Thyroid problems (with a TSH test)
• Other conditions, such as toxoplasmosis, parvovirus B19 (also called fifth disease), and cytomegalovirus

Your doctor may want to run tests to evaluate your fertility, such as:

• Postcoital test . A small sample of your cervical fluid is taken shortly after you have sex during ovulation; your doctor examines both the fluid and the condition of the sperm in it.
• Sperm analysis. A sample of sperm is taken from your partner to determine his sperm count and sperm motility (how active the sperm are).

Finally, depending on your ethnicity, your doctor may recommend genetic tests for:

• Sickle cell anemia
• Thalassemia (an inherited form of anemia)
• Jewish genetic diseases, such as Tay-Sachs disease

If it's time for you to update your vaccines, it's important to do so before you are pregnant. Certain vaccinations, such as the MMR (measles-mumps-rubella), varicella (the virus that causes chickenpox), or hepatitis A vaccines increase the risk of birth defects. Experts advise that you wait at least 28 days after receiving some of these vaccinations before trying to conceive.

Managing Diseases

If you have an existing medical condition, such as epilepsy, hypertension, asthma, or diabetes, it's especially important to seek out medical care before getting pregnant. Not only is it crucial to keep these illnesses under control during your pregnancy for both your and your baby's sake, but some common medications used to treat these conditions -- such as hypertension drugs -- can have an adverse affect on your pregnancy. If this is true of a medication that you're currently using, your doctor may be able to suggest a substitute.

Other Considerations

Your doctor will probably recommend some other things if you're trying to conceive, for instance:

• Take 0.4 mg of folic acid every day. Folic acid, which naturally occurs in leafy green vegetables and artificially in fortified flour and rice products, has been shown to lower the risk of certain birth defects. Experts recommend that in addition to a good diet, you should take a multivitamin with folic acid daily for three months before pregnancy and at least three months into pregnancy. If you've had a previous pregnancy in which the fetus had birth defects of the brain and spinal cord, your doctor will probably recommend a higher dose of 4 mg of folic acid daily.
• Avoid drugs and alcohol. Not only should you stop taking any illicit drugs, but you should also talk with your doctor about whether you should continue taking any other medications or herbal supplements.
• Stop smoking. Smoking can make it harder to get pregnant, and it poses risks to the fetus.
• Eat well and exercise. Being over- or underweight can increase risks during pregnancy. Your doctor may also recommend that you avoid certain kinds of fish, such as swordfish, king mackerel, and shark because they may contain mercury that can cause problems in pregnancy.
• Go to the dentist. Inconclusive research shows that gum disease -- an infection of the gums caused by plaque -- may increase the risk of delivering preterm or low-birth-weight weight babies.  It's important for women trying to conceive to treat gum disease if they have it and, if they don't, to practice good oral hygiene to prevent it from developing.
• Think about the changes that having a baby will bring before you get pregnant. Having a child will affect everything in your life -- your career, your finances, and your relationship with your spouse or partner, among other things. Nine months can be a pretty short time to figure all of that out, so your doctor may be able to give some advice that will help get you ready. Your doctor may also suggest preconception classes at a local hospital if they're available.