Trimester means "3 months." A normal pregnancy lasts about 9 months and has 3 trimesters.
The first trimester starts when your baby is conceived. It continues through week 14 of your pregnancy. Your health care provider may talk about your pregnancy in weeks, rather than in months or trimesters.
Your first prenatal visit
You should schedule your first prenatal visit soon after you learn that you are pregnant. Your doctor or midwife will:
Draw your blood
Perform a full pelvic exam
Do a Pap smear and cultures to look for infections or problems
Your doctor or midwife will listen for your baby's heartbeat, but may not be able to hear it. Most often, the heartbeat cannot be heard until at least 6 to 7 weeks.
During this first visit, your doctor or midwife will ask you questions about:
Your overall health
Any health problems you have
Medicines, herbs, or vitamins you take
Whether or not you exercise
Whether you smoke or drink alcohol
Whether you or your partner have genetic disorders or health problems that run in your family
You will have many visits to talk about a birthing plan. You can also discuss it with your doctor or midwife at your first visit.
The first visit will also be a good time to talk about:
Eating healthy, exercising, and making lifestyle changes while you are pregnant
What to do about vaginal bleeding during early pregnancy
You will also be given prenatal vitamins with iron if you are not already taking them.
Follow-up prenatal visits
In your first trimester, you will have a prenatal visit every month. The visits may be quick, but they are still important. It is OK to bring your partner or labor coach with you.
During your visits, your doctor or midwife will:
Check your blood pressure
Check for fetal heart sounds
Take a urine sample to test for sugar or protein in your urine. If either of these is found, it could mean that you have gestational diabetes or high blood pressure caused by pregnancy.
At the end of each visit, your doctor or midwife will tell you what changes to expect before your next visit. Tell your doctor if you have any problems or concerns. It is OK to talk about them even if you do not feel that they are important or related to your pregnancy.
At your first visit, your doctor or midwife will draw blood for a group of tests known as the prenatal panel. These tests are done to find problems or infections early in the pregnancy.
This panel of tests includes, but is not limited to:
A complete blood count (CBC)
Blood typing (including Rh screen)
Rubella viral antigen screen (this shows how immune you are to the disease Rubella)
Hepatitis panel (this shows if you are positive for hepatitis A, B, or C)
HIV test (this test shows if you are positive for the virus that causes AIDS)
Cystic fibrosis screen (this test shows if you are a carrier for cystic fibrosis)
A urine analysis and culture
An ultrasound is a simple, painless procedure. A wand that uses sound waves will be placed on your belly. The sound waves will let your doctor or midwife see the baby.
You should have an ultrasound done in the first trimester to get an idea of your due date.
All women are offered genetic testing to screen for birth defects and genetic problems, such as Down syndrome or brain and spinal column defects.
If your doctor thinks that you need any of these tests, talk about which ones will be best for you.
Be sure to ask about what the results could mean for you and your baby.
A genetic counselor can help you understand your risks and tests results.
There are many options now for genetic testing. Some of these tests carry some risks to your baby, while others do not.
Women who may be at higher risk for these genetic problems include:
Women who have had a fetus with genetic problems in earlier pregnancies
Women, age 35 or older
Women with a strong family history of inherited birth defects
In one test, your health care provider can use an ultrasound to measure the back of the baby's neck. This is called nuchal translucency.
A blood test is also done.
Together, these two measures will tell if the baby is at risk for having Down syndrome.
If a test called a quadruple screen is done in the second trimester, the results of both tests are more accurate than doing either test alone. This is called integrated screening.
A newer test, called cell free DNA testing, looks for small pieces of your baby's genes in a sample of blood from the mother. This test is newer, but offers a lot of promise for accuracy without risks of miscarriage.
You have increased discharge or a discharge with odor
You have a fever, chills, or pain when passing urine
You have any questions or concerns about your health or your pregnancy
Gregory KD, Niebyl JR, Johnson TRB. Preconception and prenatal care: part of the continuum. In: Gabbe SG, Niebyl JR, Simpson JL, et al, eds. Obstetrics: Normal and Problem Pregnancies. 6th ed. Philadelphia, PA: Saunders Elsevier; 2012:chap 6.
Williams DE, Pridjian G. Obstetrics, In: Rakel RE, ed. Textbook of Family Medicine. 8th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 21.
Cynthia D. White, MD, Fellow American College of Obstetricians and Gynecologists, Group Health Cooperative, Bellevue, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.