Preconception counseling
At least three months before trying to get pregnant, women should see either a doctor or midwife, Graves advises. It's called preconception counseling, and it helps women know the steps they must take to ensure a healthy pregnancy. "A doctor can help make sure everything is in order," she tells WebMD.

If you have chronic medical problems like obesity, diabetes, high blood pressure, or asthma, you must get them under control before you become pregnant. If you need to lose weight, this is the best time to do it—not after you become pregnant.

Depression is another problem that can affect your pregnancy. If you are depressed when you become pregnant, you are more likely to use tobacco, alcohol and illegal drugs, which can harm your baby. You may also have difficulty bonding with your baby and experience postpartum depression, which is higher in women with a history of depressive illness.

To get help, talk to your friends, your partner, your family—and if that isn't enough, consider therapy and possibly antidepressants. While recent research shows antidepressants may pose small risks to the fetus, many doctors believe a depressed mother isn't healthy for a fetus or a baby—and encourage women to take antidepressants during pregnancy if they need them. Your doctor can help you decide what's best for you.

It's also important to share with your doctor your family history, including incidence of twins, mental retardation, blindness, deafness, cystic fibrosis, congenital birth defects, Tay-Sachs disease, sickle trait/sickle cell, and thalassemia.