3rd Trimester - 6 to 9 months
The Mother’s Physical Symptoms
During this stage of pregnancy, the uterus rises up to the base of the sternum and occupies much of the pelvis and abdomen.
Many women experience heartburn and are better eating little and often, avoiding rich or spicy foods. Constipation and hemorrhoids are another common problem as high progesterone levels slow down peristalsis, however eating foods rich in fiber will help. The baby may press on the bladder, causing frequent urination.
As weight is gained and more fluid is retained, edema in the ankles and legs is likely and varicose veins or dilated capillaries often appear. Lower back ache will tend to become noticeable if it hasn’t in earlier weeks. Most women are slower in their actions, feel warmer and become tired and breathless more easily. Blood pressure may rise.
The Mother’s Emotions
While some women remain active right up to the end of their pregnancy, many women feel the need to gradually decrease their activity as the date of childbirth approaches. Physical changes can bring increasing discomfort, making vigorous activity difficult.
Sleeplessness is a common problem in later pregnancy due to physical discomfort and this can be accompanied by increased anxiety about the health of the baby or the impending birth. Many women feel impatient and can’t wait for the pregnancy to be over.
Sometimes a strong “nesting instinct” makes the mother clean and tidy everything possible in preparation for the birth.
The Developing Baby
During this trimester, the baby will grow and develop to weigh an average of 3.5kg and be up to 50cm in length by the end of the pregnancy. All the organs will mature although the lungs are the last to do so and babies born prematurely may still need help with breathing.
The head engages into the pelvis at about week 36 and birth can occur at any time afterwards. This also makes the mother more comfortable, reducing pressure from the upper abdominal organs such as the stomach and making breathing easier.