Many women don't know they are pregnant until several weeks after they have conceived. These early weeks are key for the baby growing inside you. During those early weeks, your health and nutrition can affect your baby's growth. Good health and health care before you become pregnant— also called preconception care—will help you throughout your pregnancy.
If you are planning to become pregnant, make an appointment with your doctor. Your doctor will try to identify things that may pose risks to you or your baby. You may be asked questions about your diet and lifestyle, medical history, use of birth control, past pregnancies, medications, and any diseases that may run in your family. Be open and honest when you respond to these questions. Your answers will help find out if you need to make any changes to prepare for pregnancy. You also can plan for any special care that may be needed during pregnancy.

Excess weight can cause high blood pressure or diabetes. It also puts a strain on the heart. This strain becomes even greater during pregnancy, when your heart has to work harder to supply blood to you and your baby. Women who are obese have a greater chance of problems during pregnancy, which poses risks for the baby as well as the mother. They also are at increased risk for a condition called macrosomia, in which a fetus grows too large and may have trouble fitting through the birth canal.
Being underweight can also lead to trouble getting pregnant. It also may increase your chances of giving birth to a low birth weight baby. These babies are not easier to deliver and often have problems during labor and after birth.

Infections passed through sexual contact—sexually transmitted diseases (STDs)—also are harmful during pregnancy. Many types of STDs may affect your ability to become pregnant. They also may infect and harm your baby. If you think you or your partner may have an STD, get tested and treated right away. Your partner also may need to be treated. Neither of you should have sex until you have both finished treatment. Infection with human immunodeficiency virus (HIV) can cause harm to mother and baby. Early treatment may help prevent the infection from being passed to the fetus. Because of this, your doctor will offer HIV testing, even if you have no symptoms.