Definitely. The earliest weeks of pregnancy (when you may not even know you're expecting) are full of critical moments when your baby's brain and other organs start to take shape. And being as healthy as you can before getting pregnant will help your baby have the best possible start in life.
You should visit your healthcare provider at least three months before you start trying to conceive to let her know your plans. She'll most likely ask about your medical and family history, the medications you take, any past pregnancies you may have had, and your diet and lifestyle. She'll also perform a complete examination including a breast exam and Pap smear. She should also check to make sure your vaccinations are up to date and will recommend that you start taking prenatal vitamins if you haven't already (they're packed with essential vitamins and minerals, especially folic acid, that minimize the risk of birth defects).
If you have any existing health conditions like asthma, high-blood pressure, diabetes, or sexually transmitted diseases, this checkup is especially important since it will give your doctor an opportunity to address any potential problems that could affect your pregnancy -- and develop a game plan to manage them while you're expecting. If you have a family history or ethnic background that increases your risk for having a baby with certain genetic disorders, your doctor may suggest you and your partner seek genetic testing before trying to get pregnant.
Remember, it's essential that you are completely open and honest with your doctor, even if your medical history includes hard-to-talk-about experiences like an abortion or drug use. Everything you discuss with her is confidential, and the information you provide will only increase the chances that you'll have a healthy baby.