Third Trimester

The third trimester, like the second is characterized by intensive fetal growth. The baby is completely developed and the rest of gestation is devoted to growth and weight gain. The trimester is marked with further essential brain and lung development.

The baby: the baby continues to gain weight and grow. He is able to open and close his eyes and suck his thumb. By the ninth month the baby is settling into the delivery position with his arms and legs pulled in and his head at the opening of the birth canal. As the baby grows, the frequency and strength of the fetal movements increase. This typically occurs around the 32nd week.

The mother: the mother should expect to gain about 10 pounds during this trimester. Her size will increase quickly as the baby does. Fatigue will likely become an issue in this trimester. The extra weight the mother is carrying is not only hard work for her body but it is uncomfortable, which makes sleeping difficult. Walking can also be difficult as the additional weight she has put on shifts her center of gravity over her feet. Around week 34, or half way through the trimester, the mother may begin to experience Braxton Hicks contractions. This is the mother's body practicing for labor. If the contractions get stronger and stronger over time this is a sign that the mother is actually giving birth. Braxton Hicks contractions generally maintain the same level of strength. By the end of the mother's pregnancy she should have gained on average somewhere between 25 and 30 pounds. Of this weight only 7. 4 pounds are attributable to maternal reserves and fat gained. The remainder of the weight is distributed approximately as such: fetus - 7. 5 pounds; placenta and membranes - 1. 4 pounds; amniotic fluid - 1. 8 pounds; increase in size of uterus - 2. 1 pounds; blood volume - 2. 8 pounds; increase in breast size - 0. 9 pounds; and fluid absorption in skin and tissue - 3. 7 pounds. By the third trimester stretch marks should appear on the breasts, thighs, and abdomen. They will shrink after labor and some will disappear. In some dark haired and dark complexioned women a dark line will appear on the abdomen between the navel and pubic bone. This rapidly disappears after birth. It is also common for brown patches to appear on the face and neck. These patches are called chloasma and they typically disappear after birth. In many Caucasian women, red spots will appear on the skin, particularly the face, neck and back. These are related to the increase in estrogen levels and usually appear prior to the third trimester.

Month 7

The baby begins more rapid growth and larger fat deposits collect. He stretches and kicks more rapidly. The baby's bones harden and his hearing is fully developed. The baby will not respond to external stimuli such as light, pain and sound. The amniotic fluid that surrounds the baby begins to diminish as he increases in size and swallows some of it. If the baby is born prematurely after this month, there is a good chance that he will survive.

Month 8

The baby continues to develop and mature as he stores body fat. Greater amounts of movement will be noticed and kicks will be stronger. The baby's brain is now developing rapidly as are the internal organs and systems. The lungs are not likely fully developed.

Month 9

The last month of gestation is devoted to the final stages of growth and development. All of the baby's reflexes are now fully developed. Although the baby's movement will have slowed greatly by now due to the restricted amount of space he has in the womb. If he has not already, the baby will position himself for birth, with his head in the mother's pelvis at the opening of the birth canal. The baby is likely to arrive sometime during this month. Labor could begin as early as the first week of the month (week 37) and could be as late as two weeks over due.

Common Third Trimester Medical Exams:

Typically during the 28th week of pregnancy (the first week of the third trimester), many of the exams that were performed in the first trimester are repeated to ensure that no complications have arisen and the mother's health as well as the baby's is not in jeopardy.

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