By Amy Norton, Medical Tribune News Service
A common vaginal infection may increase pregnant women's risk
for having an early miscarriage, British researchers have found.
Bacterial vaginosis (BV) during pregnancy has already been
linked to premature delivery and low birth weight in infants. Some
studies have suggested the infection raises the risk for
miscarriage in the third trimester of pregnancy, according to
researchers reporting in the July 24 issue of the British Medical
Journal.
In their own study of 770 women, the investigators from Leeds
General Infirmary in Leeds found that women who became pregnant
while infected with BV were twice as likely as non-infected women
to have a miscarriage in the first trimester.
At the beginning of the study, all of the women were attempting
to conceive through in-vitro fertilization (IVF). Nearly 25 percent
of them had BV.
Among 237 women overall who succeeded in becoming pregnant, 24
percent miscarried in the first trimester. Of women with the
infection, 36 percent suffered an early miscarriage; among women
with normal vaginal bacteria levels, the miscarriage rate was 18.5
percent; among those with intermediate bacterial levels, 23 percent
miscarried.
Dr. Janet Wilson and colleagues found that even after accounting
for other miscarriage risk factors, such as older age, smoking and
previous miscarriages, BV remained linked to higher risk.
How BV might affect miscarriage is unclear. The infection occurs
when several different types of microbes outnumber bacteria that
are normally present in the vagina. BV is characterized by vaginal
discharge and irritation, but it often causes no symptoms. Studies
have shown that anywhere from 13 percent to 31 percent of pregnant
women have the infection.
Some research has suggested that the infection can lead to
pelvic inflammatory disease, which is a major cause of infertility
in women. Wilson's team speculated that the women with bacterial
vaginosis in their study may have had inflammation in the uterus, a
condition called endometritis.
``Inflammation in the uterus can make it hard for the embryo to
grow,'' Wilson said. If this is the route by which BV affects
miscarriage risk, Wilson added, then the link probably also exists
among women who conceive naturally.
She and her colleagues examined women undergoing IVF because it
allowed them to follow the early stages of pregnancy right from
conception. ``It was an ideal group to study,'' Wilson said.
One finding of the study, however, might not translate to
natural conception. Subjects with bacterial vaginosis had no
greater difficulty conceiving than did women with normal bacteria
levels -- 32 percent of infected women and 30 percent of
non-infected women conceived. But because of BV's link to
infertility, conception rates may be lower among infected women
trying to conceive naturally, Wilson noted.
``This study,'' she said, ``shows that BV causes problems at
every stage of pregnancy, not just later on.''
Because of BV's established link to premature birth, the Centers
for Disease Control and Prevention in Atlanta advises that all
pregnant women with a history of premature delivery be tested for
the infection.
British authorities maintain the same recommendation, Wilson
said. If these women are found to have BV, they receive antibiotics
to treat the condition.
It might be a good idea, Wilson said, for all women planning a
pregnancy to be screened for the infection.
