Women's Health Matters

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Third trimester

Stages of pregnancy | First trimester | Second trimester | Third trimester

By the third trimester, both you and your partner are anticipating the birth of your child. You may be becoming impatient with your body and feeling vulnerable and dependent on others. During the last part of the third trimester, many women experience a burst of energy and start “nesting” – setting up and preparing their home for a child. Both you and your partner may be feeling excited, as well as somewhat anxious, about the quickly approaching arrival of your baby. You may continue to have vivid dreams about your child, especially if it is your first pregnancy.

Your growing and changing body may make some lovemaking positions uncomfortable; this may be a time to try some new positions. Or you may find that the back pain and other discomforts that many women experience towards the end of the pregnancy make you less interested in sex.

Physically, the third trimester tends to be more uncomfortable. You may experience some of the following:

  • backache
  • leg cramps
  • heartburn
  • a dark line, called linea nigra, which runs vertically from your belly button to your pubic bone
  • shortness of breath
  • the need to urinate frequently
  • the loss of bladder control when you sneeze or cough
  • Braxton-Hicks contractions (painless contractions of the uterus)

At 38 weeks, the top of your uterus will have reached your breastbone and you may begin to experience early signs of labour.

During this period, the most dramatic change in the fetus is its continued growth. By the seventh month, it weighs about two and a half pounds, and is approximately 15 inches long. By the eighth month, the fetus weighs about 5 pounds and is 16 to 18 inches long. During the last month of pregnancy the fetus weighs seven or eight pounds and may be more than 20 inches long. In addition:

  • the fetus’ skin wrinkles become less pronounced as body fat accumulates and begins to smooth out the body
  • eyes open and close
  • fetus responds to light
  • lanugo disappears
  • fetus stores iron and builds skeleton

The head (or whatever part will be born first) settles into the pelvic canal between 37 and 40 weeks. This is called engagement or lightening. You will likely notice that the fetus' position has changed, which can cause you to feel increased pressure on your bladder.

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  • A publication of:
  • Women's College Hospital