NEW YORK, Mar 9: Infertility due to abnormalities of the fallopian tube or uterus raises the risk that in vitro fertilization or other assisted reproductive techniques (ART) will result in an ''ectopic'' pregnancy, one in which the fertilized egg attaches itself outside the normal uterus location, new research shows.
Ectopic pregnancies typically occur in the fallopian tubes, thus they're sometimes called ''tubal pregnancies.'' Outside of the uterus, the fetus is unable to grow properly and may actually rupture the fallopian tube, an event that can be fatal for the mother. Early ectopic pregnancies are often treated with drugs to dissolve the fertilized egg, whereas later on, surgical removal of the abnormal pregnancy is often required.
To investigate factors associated with ectopic pregnancy risk with ART, Dr Laura A. Schieve, from the Centers for Disease Control and Prevention in Atlanta, and her associates analyzed outcomes reported to the CDC's ART Registry between 1999 and 2001.
Of the 94,118 pregnancies included in the registry, 2.1 per cent were ectopic. The investigators note that the rate is 2.0 per cent in the general population.
Tubal and uterine abnormalities raised the risk of ectopic pregnancy by 38 to 168 per cent, the report in the journal Obstetrics and Gynecology indicates.
Transfer of a fertilized egg into the fallopian tubes, an ART procedure known as ''ZIFT,'' increased the risk of ectopic pregnancy by 75 per cent. The risk also rose when three or more embryos were implanted into the mother.
''Maternal age, prior spontaneous abortions, use of (other types of ART) were not significant predictors of ectopic pregnancy,'' the authors note.
''As new technologies in ART become available, their potential impact on ectopic pregnancy should be investigated,'' Schieve and her associates conclude.