The Facts
An ectopic pregnancy occurs when a fertilized egg implants itself outside
of the uterus. Ectopic pregnancies usually occur in a fallopian tube (called
a tubal pregnancy). Occasionally, the egg may lodge itself in the ovary,
and more rarely, in the cervical canal or the abdominal or pelvic cavities.
The fertilized egg doesn't usually grow into a recognizable embryo and can't
be transplanted into the uterus.
In a normal pregnancy, the egg is fertilized in the fallopian tube. Little
hairs in the fallopian tube move the egg down to the uterus, where it implants
itself. If there's scar tissue in the fallopian tube, or it's blocked for some
other reason, the fetus will begin to grow outside of the uterus. A woman who
has an ectopic pregnancy must have the pregnancy removed because it can't develop
properly outside of the uterus and it is dangerous for a woman's health.
Although they're becoming more common in recent years, ectopic pregnancies
are generally rare.
Causes
If you've had an infection in the pelvic region (e.g., pelvic inflammatory
disease) or pelvic surgery, or were born with a medical condition that narrowed
your fallopian tubes, you have a greater chance of having an ectopic pregnancy.
A previous ectopic pregnancy can also increase your risk of a second ectopic
pregnancy. An unsuccessful tubal ligation, a sterilization procedure in which
the fallopian tubes are cut or blocked, can contribute to the risk of an ectopic
pregnancy.
Ectopic pregnancies have also been linked to the use progesterone-only birth
control pills, and the morning-after pill. Women who use IUDs, especially those
containing progesterone, have a higher risk of having an ectopic pregnancy if
they do become pregnant despite using the IUD. Women who were exposed to a medication
called diethylstilbestrol* (a synthetic estrogen) in their mother's womb are
also at greater risk of ectopic pregnancy.
