Once a woman has reached the pregnancy stages, last trimester, she becomes increasingly eager for the birth. The fetus has accomplished most of its development. All the facial features are obvious. The fingers and toes are well-formed. In fact, it is even possible for the fetus to suck its thumb at this stage.

Much of what happens during this last trimester strengthens what already exists. For example, the lungs have now been completely formed and the fetus could begin breathing air if it had to. The additional few weeks of the pregnancy will allow those tiny lungs to develop and strengthen even more, limiting the possibility of early breathing problems.

The brain of the fetus is also developing. The basic components of the brain now exist, but it is smooth and doesnt have the wrinkles that are generally associated with brain development. The last several weeks of the pregnancy stages, last trimester allow the brain time to grow, curving in upon itself, thus developing the familiar wrinkles.

The bones of the fetus are all developed and present, but they are still pliable, which will make the birth process easier. After the delivery, some of the bones will harden and fuse. The fact that the bones are present means that the bone marrow can produce red blood cells. Again, the fetus could survive if delivered early, but extra weeks of development will allow the bone marrow to refine its capability and produce more red blood cells.

The fetus is almost ready to survive on its own. In the pregnancy stages, last trimester, during week 30, the fetus could be delivered, though it would be considered premature. In most cases, some form of medical help would be needed to allow the newborn to grow large enough that the physician will allow the mother to take the infant home. By week 38 of the pregnancy stages, last trimester, the fetus could be delivered and not need medical help to survive, but most physicians would rather wait for week 40 before the baby is delivered. These last two weeks allow the fetus to gain additional weight.

During the pregnancy stages, last trimester, the fetus doesnt have much room to move. Much of the movement is by the hands and feet, but generally, the fetus is making a shift to prepare itself to exit the birth canal. It is gaining weight more quickly than it is gaining length. Mothers will notice that the fetus will respond to sudden, loud noises. It will also respond to soothing sounds, such as the mothers voice.

As the fetus positions itself for birth, it will sink into the pelvic area. This will cause pressure on the bladder and the expectant mother will find herself making frequent trips to the bathroom. She may also experience false labor pains. Ideally, the expectant mother will have asked her physician plenty of questions and she will be prepared for the birth of her baby.