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Part 2-Labor and Delivery

The weeks and months have passed, and your due date is rapidly approaching. The event that you have waited, planned, and hoped for is almost here. It seems that everywhere you go people have stories to share about their own birth experiences. Some sound sublime and others sound, well, just awful. Why do some women have such great labors and others such miserable ones? What can you do to ensure the best possible labor and delivery?

Someone once described labor as dependent on the three Ps-pelvis, passenger, and power-and that's not far from the truth. These three factors, individually and in combination, determine the length of your labor and whether you ultimately might need a Caesarean section.

The first P stands for the pelvis. What is meant here is the bony pelvis, the bone structure that supports the lower body and through which the baby's head must pass during labor. The mother's soft tissues will stretch during labor and delivery, but the pelvic opening, being bone, will not. Not surprisingly, women with a small pelvic opening will find it difficult, if not impossible, to deliver a large baby.

Of course, most women have a pelvic opening that is more than adequate to deliver an average baby. Your doctor or midwife will most likely do an internal exam a few weeks before your delivery date to assess your pelvis. The important thing is not the absolute size of the pelvic opening, but rather its relative size compared to the size of the baby's head.

The second P refers to the passenger (your baby). While it will be more difficult to deliver a larger baby than a smaller one, it's not the baby's weight that counts; it's the size and the position of the fetal head that are most important. Obviously, a bigger fetus will have a bigger head, but there are ways for the fetus to position his or her head that will make it easier to pass through the pelvis.

During the course of labor, while the cervix is dilating, the pressure of the uterine contractions encourages the fetus to assume the position in which the smallest possible diameter of the head is "presenting," or coming first. Not all babies cooperate, however, and if yours decides to go through the pelvis facing up or turned sideways rather than down toward your back, your labor will be longer and more difficult. It is much easier to deliver a baby whose head is tucked down on his or her chest rather than one attempting to come out face first (fortunately, this is a very uncommon position).

Even if the fetal head is large (compared to the mother's pelvis), or is in a less than ideal position, all is not lost. That's because the fetal head is capable of changing shape during labor. The bones of the fetal skull are not fastened to each other the way they are in the adult skull. The bones are free to move in relation to each other, allowing the fetal head to conform to the size and shape of the pelvic opening. This process is known as molding. Molding takes time, which is why a baby born after a long labor has a "cone head." The head actually gets longer and thinner to fit through the pelvic opening! It will return to normal shape in 24-48 hours, without any harm to the baby.

The final P stands for power-that is, the power of the uterine contractions. Not all contractions are alike; some are stronger than others. Usually, as labor progresses, the contractions become longer and stronger. However, some women never have strong enough contractions to get the job done, that is, to cause the cervix to dilate the necessary 10 cm. and to push the baby out. If your practitioner suspects that your contractions are not strong enough, she or he can strengthen them by giving you Pitocin, a synthetic version of the hormone oxytocin, which causes contractions.

If you need Pitocin, you will probably realize it at the same time that your practitioner does. Perhaps you've been in labor for many hours without dilation of your cervix, or maybe you made great progress until a certain point but then, despite additional hours of labor, nothing changes. Pitocin may then get you back on track by causing the contractions to become stronger and more effective.

However, there's no guarantee that Pitocin will cause continued progress. The uterus is an amazing organ, and it appears to be able to sense if the fetus is too large to deliver. In such cases, the cervix will not dilate any further, even with Pitocin. Then, it is clear that a C-section needs to be done.

What can you do to improve the course of your labor? Well, not much. The size of your pelvis was determined long ago, and you don't have any control over the size of the baby or the position it decides to assume. There are, however, a number of things you can do to ensure that your contractions are as strong and effective as they can be. The following seven chapters discuss the process of labor and delivery in detail, from the first contraction to delivery of the placenta, placing special emphasis on the things that you can do to encourage a smooth and efficient labor.