A life-threatening type of pregnancy in which an embryo grows outside the uterus now accounts for nearly 1 out of every 50 pregnancies and is increasing among women who postponed having children and among poor, minority women.
In 1987, the last year for which complete information is available, a record 88,000 women were hospitalized for these ectopic pregnancies, nearly 10,000 more than the previous high in 1985, according to the federal Centers for Disease Control.
Although the death rate from ectopic pregnancies has declined dramatically because of earlier diagnosis and better treatment, they still accounted for 12 percent of all maternal deaths in 1987, said Dr. Kees P. Nederlof of the centers' division of reproductive health.
The increase in the rate of ectopic pregnancies is primarily due to the unchecked spread of chlamydia, a sexually transmitted disease, health experts said.
The infection can leave scar tissue on the lining of the Fallopian tubes, either totally or partially blocking them. Totally blocked tubes result in infertility. Partially blocked tubes may prevent a fertilized egg from traversing into the uterus.
The embryo can rupture the tube and cause life-threatening bleeding if it is not removed.
About 4 million Americans are infected with chlamydia each year, said the CDC.
"The disaster with chlamydia is that most women who are infected have neither signs nor symptoms," said Dr. Julius Schachter, professorof epidemiology and laboratory medicine at the University of California, San Francisco.
The underlying problem, says Luis Cibils, professor of obstetrics and gynecology at the University of Chicago, is that it is extremely difficult to control sexually transmitted diseases and that some of them, especially chlamydia and gonorrhea, specifically infect the Fallopian tubes, causing a condition called pelvic inflammatory disease.
"The only way to stop the increasing rate of ectopic pregnancies is to prevent sexually transmitted diseases, and we are losing that battle," he said.
More than 12 million cases of sexually transmitted disease occur each year, according to the CDC. In addition to chlamydia, there are 1.4 million cases of gonorrhea and 130,000 cases of syphilis.
Chlamydia is a cross between a virus and a bacteria. It is difficult to diagnose because it requires expensive and time-consuming cell cultures, but it is easy to treat since it can be killed by antibiotics.