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Pregnancy: The Third Trimester

The Third Trimester: What You Need to Know

  • As you begin the third trimester, your health care provider or midwife may change the schedule of your prenatal visits from monthly to every two weeks.

  • It’s a good idea to start taking childbirth classes in preparation for your baby’s birth, especially if this is your first pregnancy.

  • By the end of the third trimester, the fetus is about 19 to 21 inches long and weighs, on average, 6 to 9 pounds.

Prenatal Visits During the Third Trimester

During your second and third trimester prenatal visits, your health care provider or midwife may check the following, depending on your current medical condition and the health of your fetus:

  • Any current symptoms or discomforts

  • Your weight

  • Your blood pressure

  • Urine test. This is to find albumin, a protein that may indicate pre-eclampsia or toxemia, and glucose, which may indicate hyperglycemia.

  • Position, growth and development of your fetus

  • Height of the fundus (top of the uterus)

  • Fetal heartbeat

As you begin the third trimester, your health care provider or midwife will change the schedule of your prenatal visits from monthly to every two weeks. Your prenatal visits may be scheduled once every week in the last month. This schedule will depend on your medical condition, the growth and development of the fetus, and your health care provider or midwife’s preference.

Toward the later weeks of the pregnancy (starting at approximately the 38th week), a pelvic exam may be done to determine the dilation and effacement of the cervix. Your health care provider or midwife will also ask about any contractions and discuss labor and delivery procedures.

The Third Trimester: What to Expect

The third trimester marks the home stretch, as you prepare for the delivery of your baby. The fetus is continuing to grow in weight and size, and the body systems finish maturing. You may feel more uncomfortable now as you continue to gain weight and begin to have false labor contractions (called Braxton-Hicks contractions).

During the third trimester, it is a good idea to start taking childbirth classes in preparation for the big day. This is especially true in the case of first pregnancies.

Johns Hopkins Hospital Designated as Baby-Friendly

Mother holding happy baby

The Baby-Friendly Hospital Initiative, a global program launched by the World Health Organization and the United Nations Children’s Fund, has designated The Johns Hopkins Hospital as Baby-Friendly. This designation is given to hospitals and birthing centers that offer an optimal level of care for infant feeding and mother-baby bonding.

Learn more.

The Third Trimester: Changes to Your Body

Illustration demonstrating physical variations in carrying an unborn baby.
Click Image to Enlarge

In the third trimester, some women become increasingly uncomfortable as their due date nears. As the fetus grows in size and crowds the abdominal cavity, some mothers-to-be have difficulty taking deep breaths or getting comfortable at night for sleep, while others are free from any discomfort as they anxiously await the arrival of their new son or daughter.

The following is a list of changes and symptoms that you may experience during the third trimester:

  • Your fetus radiates body heat, causing you to feel hot from increased skin temperature.

  • The increased urinary frequency returns due to increased pressure being placed on the bladder.

  • Blood pressure may decrease as the fetus presses on the main vein that returns blood to the heart.

  • Swelling of the ankles, hands and face may happen (called edema), as you continue to retain fluids.

  • Hair may begin to grow on your arms, legs and face due to increased hormone stimulation of hair follicles. Hair may also feel coarser.

  • Leg cramps may happen more often.

  • Braxton-Hicks contractions (false labor) may begin to happen at irregular intervals in preparation for childbirth.

  • Stretch marks may appear on the stomach, breast, thighs and buttocks.

  • Colostrum (a fluid in the breasts that nourishes the baby until the breast milk becomes available) may begin to leak from your nipples.

  • Dry, itchy skin may persist, particularly on the stomach, as the skin continues to grow and stretch.

  • Your libido (sexual drive) may decrease.

  • Skin pigmentation may become more apparent, especially dark patches of skin on the face.

  • Constipation, heartburn and indigestion may continue.

  • You will have increased white-colored vaginal discharge (leukorrhea), which may contain more mucus.

  • Backaches may persist and increase in intensity.

  • Hemorrhoids may persist and increase in severity.

  • Varicose veins in the legs may persist and increase in severity.

The Third Trimester: Fetal Development

Fetal growth from weeks eight through 40 is depicted visually in this chart.
Click Image to Enlarge

During the third trimester, your fetus continues to grow in size and weight. The lungs are still maturing, and the fetus begins to position itself head down. By the end of the third trimester, the fetus is about 19 to 21 inches long and weighs, on average, 6 to 9 pounds. Fetal development during the third trimester includes:

  • The fetus can see and hear.

  • The brain continues to develop.

  • The kidneys and lungs continue to mature.

  • By the 36th week, the head may “engage” (drop into the pelvic area), a process called lightening.

  • The bones of the skull remain soft to make it easier to pass through the birth canal.

  • For many babies, the irises of the eyes are slate blue. The permanent eye color will not appear until several days or weeks after birth.

  • The fetus can suck its thumb and has the ability to cry.

  • By 38 to 40 weeks, the fetus’ lanugo (fine, soft hair on the body and limbs) has disappeared almost completely.

  • By 38 to 40 weeks, the lungs have matured completely.

  • The baby is covered in vernix caseosa (or simply called vernix), a creamy, protective coating on the skin.

  • The head will usually turn downward during the last couple of weeks of pregnancy.

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