Ectopic - or tubal - pregnancies can be dangerous for mothers, leading to rupture of the fallopian tube and possible hemorrhage, and they appear to be on the rise, according to a new study.
An ectopic pregnancy occurs when egg and sperm unite outside of the uterus, most commonly within a fallopian tube. Although some experts thought the problem was becoming less common, the study suggests otherwise.
"Using the case definition strategies that the CDC used for national surveillance we did not see the decline in rates that some other, largely inpatient-based, sources have reported, but, rather, slightly increasing rates," said Britton Trabert, Ph.D., a research fellow at the National Cancer Institute.
The study looked at female inpatients and outpatients, ages 15 to 44 years, enrolled in Group Health Cooperative over a 15-year period. Group Health Cooperative is a managed care system that serves residents of the state of Washington and of western Idaho.
The new study, which appears online and in the May issue of the American Journal of Preventive Medicine, looked at 2,114 cases of ectopic pregnancy. Of these, 726 occurred in inpatients and 1,388 in outpatients. Trabert conducted the study as part of her doctoral dissertation at the University of Washington.
The study did not focus on the reasons for any of the trends, which included an increase from 19.2 to 26.2 tubal pregnancies per 1,000 pregnancies over the 1993 to 2007 timeframe. "There are a number of factors that have contributed to this apparent increase in ectopic pregnancies," said Debbie Kirkpatrick M.D., a vice chair for clinical affairs in the obstetrics and gynecology department at Indiana University.
Among these, increased sensitivity of pregnancy tests over the 15 years of the study could contribute to an apparent increase in ectopic pregnancies, since women would discover pregnancies that might have gone undetected previously. Another likely factor is the increased incidence of sexually transmitted diseases, "which damage fallopian tubes and increase the risk of ectopic pregnancy," Kirkpatrick said.
Kirkpatrick, who has no affiliation with the study, described how medical advances might also play a part in the rise: "Delayed childbearing leads to more assisted reproductive technologies, which lead to a higher risk of ectopic pregnancy," she said.
Intrauterine devices (IUDs) and tubal sterilization rates have also gained popularity as birth control strategies over the 15 years. "If either fails, there is an increased rate of ectopic pregnancy," Kirkpatrick said. Likewise, the move toward medical rather than surgical treatment for ectopic pregnancies leaves the damaged fallopian tube in place, which increases the risk of future fertilizations occurring in the tube.
She and the study authors agree that the shift from inpatient, surgical treatment for ectopic pregnancies to outpatient, medical treatment has made quantifying the rate of occurrences more challenging for researchers.