Understanding the Incompetent Cervix

Premature delivery is one of the most expensive complications of human existence. Besides the devastating emotional costs and physical suffering, there are the astronomical financial burdens put on families and society for the lifespans of babies affected.

Causes of Premature Delivery

Before we go into detail on the incompetent cervix, however, let's get a cursory primer on some other causes of premature delivery out of the way. Infection inside the womb (amnionitis) can cause uterine irritability which can in turn cause contractions, usually a benefit to an unborn baby exposed to such an infection, but with the trade-off of premature delivery. Trauma such as car accidents or falls can do the same, especially if there is injury to the placenta that provokes bleeding. The placenta itself is a common cause of premature delivery, with premature separation (called abruptio placentae, or abruption) decreasing the amount of surface area responsible for oxygen exchange from mother to baby. Besides unknown causes, cigarette smoking or cocaine use can cause abruptions.

But premature delivery can often be a result of disability to actually hold in the baby. The cervix is that circular, muscular, and fibrous opening that holds tight until contractions cause enough force to push the baby's head against it as a dilating wedge. When it finally gives way and opens, this is what is called real labor. But if there is a weakness in its structural integrity, it can fall open without the usual forces necessary. This is an incompetent cervix.

The Weakened Cervix

Actual labor at term is a complex mechanism that just happens to fall into place like so many tumblers in a lock. We are designed with a clock that ideally lines up the chemical and physiological tumblers only after a baby is mature enough to survive. But if the cervix is weak, gravity alone may be enough to allow even a premature baby's weight to cause it to dilate. The gate is open, so to speak, and the baby can follow uninhibited into the outside world. The earlier before term this happens, the worse off for the baby.

In the 1950s an estrogen called DES was used to try to prevent miscarriage. Not only did it not work, but it also caused congenital abnormalities in the developing female babies the mothers were carrying. These abnormalities were alterations in their daughters' reproductive tracts, ranging everywhere to weakening of the cervix all the way to cancer.

By the late 1990s, most of the children of these mothers had their windows of risk open and close, so that's a moot point. But the very problems that haunt a lot of today's handicapped generation are due to the cervical weakening of these DES-affected women who came to childbearing age. With congenital weakening in these patients, premature babies were born, many with the complications of prematurity that are at this time exacting a heavy price in money and heartache.

With the early diagnosis of precancerous lesions of the cervix, more and more young women and adolescents are having their cervices altered by freezing or burning away these lesions. Although this typically doesn't set one up for a weakened cervix, it can. Tragically, obstetricians often don't know there's a problem until a pregnancy so troubled forces a patient to undergo surgery to keep the cervix closed with or without continued bed rest.