Definition Pregnancy is the process of childbearing. Measured from the start of a woman's last normal menstrual period or LNMP, it usually lasts about 40 weeks or roughly 9 months.
The third trimester of pregnancy generally spans weeks 28 through 40, though healthy babies may be born a bit sooner or later. Although most women undergo many of the same physical changes during this time, no two pregnancies are alike.
What is the information for this topic? During the third trimester, continuing growth and development in mother and foetus cause many changes to occur.
Women may notice:
movements of the foetus can be felt more strongly
abdominal pain that may or may not be true labour pains
shortness of breath because the uterus is pushing against the diaphragm. The diaphragm is a flat, strong muscle that aids in breathing. Towards the end of the third trimester, the baby may drop down into a lower position. This will make it easier for the mother to breathe.
a need to urinate more often when the baby drops down into a lower position in the pelvis
yellow, watery fluid leaking from her nipples, known as colustrum
her navel sticking out
As the body readies for birth, a woman's cervix begins to thin out and open.
During the third trimester, certain discomforts and mood changes may occur:
fatigue or extra energy, or alternate periods of both
increasingly heavy white vaginal discharge
more mild lower abdominal pains with uterine tightening and then relaxing
increasing clumsiness as shape and balance changes
anxiety, impatience, and restlessness
irritability and unusual sensitivity
In the foetus:
as the foetus gets bigger, it has less room to kick and stretch, so the movements felt by the mother may decrease
fine body hair disappears
most bones harden, but bones of the head stay soft and flexible for birth
as the time for birth approaches, the foetus usually moves down into the pelvis and settles into a good position
At 40 weeks, the foetus is considered full term. It is about 20 inches long and weighs 6 to 9 pounds.
The most common health risks and concerns in the third trimester of pregnancy are:
premature labour beginning before the 37th week of pregnancy. If the labour cannot be stopped, the baby may be born too early. This can cause many problems with the baby's health and development.
During the third trimester of pregnancy, monitoring is more frequent. In the seventh and eighth months, it may include:
mother's weight and blood pressure
urine test for sugar and protein
foetal heartbeat
height of the uterus
size and position of the foetus
Any worrisome symptoms or concerns should be reported to the doctor. After the 32nd week, the doctor may suggest monitoring every two weeks.
Monitoring occurs weekly after about the 36th week as the ninth month begins. It may include all of the above as well as examination of the cervix and discussion about the signs and symptoms of labour.
Author: Dr. Karen Wolfe, MBBS, MA Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
