A normal pregnancy lasts about 40 weeks. The first trimester lasts from your last period through the 12th week of pregnancy. The second trimester lasts from the 13th week through the 23rd week. The third trimester lasts from the 24th week until your baby is born. If you know the date of your last period, your healthcare provider can estimate your due date. You may give birth to your baby any time from 37 weeks to 2 weeks after your due date.

What is prenatal care?

Prenatal care is a series of visits with your healthcare provider throughout your pregnancy. Prenatal care can help prevent problems during pregnancy and childbirth. At each prenatal visit, your healthcare provider will weigh you and check your blood pressure. He or she will also check your baby's heartbeat and growth. You may need the following at some visits:

  • A pelvic exam allows your healthcare provider to see your cervix (the bottom part of your uterus). Your provider will use a speculum to open your vagina. He or she will check the size and shape of your uterus. At your first prenatal visit, you may also have a Pap smear. This is a test to check your cervix for abnormal cells.
  • Blood tests may be done to check for any of the following:
    • Gestational diabetes or anemia (low iron level)
    • Blood type or Rh factor, or certain birth defects
    • Immunity to certain diseases, such as chickenpox or rubella
    • An infection, such as a sexually transmitted infection, HIV, or hepatitis B
  • Hepatitis B may need to be prevented or treated. Hepatitis B is inflammation of the liver caused by the hepatitis B virus (HBV). HBV can spread from a mother to her baby during delivery. You will be checked for HBV as early as possible in the first trimester of each pregnancy. You need the test even if you received the hepatitis B vaccine or were tested before. You may need to have an HBV infection treated before you give birth.
  • Urine tests may also be done to check for sugar and protein. These can be signs of gestational diabetes or preeclampsia. Urine tests may also be done to check for signs of infection.
  • A gestational diabetes screen may be done. Your healthcare provider may order either a 1-step or 2-step oral glucose tolerance test (OGTT).
    • 1-step OGTT: Your blood sugar level will be tested after you have not eaten for 8 hours (fasting). You will then be given a glucose drink. Your level will be tested again 1 hour and 2 hours after you finish the drink.
    • 2-step OGTT: You do not have to fast for the first part of the test. You will have the glucose drink at any time of day. Your blood sugar level will be checked 1 hour later. If your blood sugar is higher than a certain level, another test will be ordered. You will fast and your blood sugar level will be tested. You will have the glucose drink. Your blood will be tested again 1 hour, 2 hours, and 3 hours after you finish the glucose drink.

A fetal ultrasound shows pictures of your baby inside your uterus. The pictures are used to check your baby's development, movement, and position.

  • Genetic disorder screening tests may be offered to you. These tests check your baby's risk for genetic disorders such as Down syndrome. A screening test may include blood tests and an ultrasound. Blood tests may be used to check your DNA or your partner's DNA. Genetic tests are not always accurate or complete. Your baby may be born with a genetic disorder that did not show up in the tests. Talk to your healthcare provider about any concerns you have with genetic testing.

What can I do to have a healthy pregnancy?

Eat a variety of healthy foods. Healthy foods include fruits, vegetables, whole-grain breads, low-fat dairy foods, beans, lean meats, and fish. Drink liquids as directed. Ask how much liquid to drink each day and which liquids are best for you. Limit caffeine to less than 200 milligrams each day. Limit your intake of fish to 2 servings each week. Choose fish low in mercury such as canned light tuna, shrimp, crab, salmon, cod, or tilapia. Do not eat fish high in mercury such as swordfish, tilefish, king mackerel, and shark.