Early Pregnancy Bleeding Less Risky Than Thought

Miscarriage percent far lower, new study says

TUESDAY, Feb. 11, 2003 (HealthDayNews) -- As many as 30 percent of women experience bleeding during the first three months of pregnancy, yet until recently little was known about how the symptom affects pregnancy outcome.

Now, new research suggests that while women with first trimester bleeding are more likely to have a miscarriage than women who don't bleed, the risk is much lower than had been thought. Although previous research had pinpointed the risk of miscarriage after bleeding at up to 30 percent, the new study shows the risk is actually less than 5 percent.

"If you have bleeding and a viable pregnancy at the time of ultrasound, your chances of going to term are very good," says lead author Dr. Joshua Weiss of Columbia University in New York City.

Nonetheless, early bleeding should be a red flag to physicians that patients should be closely monitored and screened for pregnancy complications, Weiss adds.

That's because the study, based on data collected from 13,752 women treated at 15 medical institutions, also showed that women with first-trimester bleeding are more likely to experience complications such as premature delivery and hypertensive disorders. And it found that pregnancy outcomes worsen when vaginal bleeding is heaviest.

Women with heavy bleeding were between two times and four times more likely to experience a host of complications that included premature labor, early membrane rupture and separation of the placenta from the uterus.

"When a patient has heavy bleeding, physicians should consider a cervical length scan as well as a fetal growth scan at 28 to 36 weeks," Weiss says.

A number of factors cause vaginal bleeding during the first trimester of pregnancy, including cervical infection, spontaneous abortion or implantation of the fertilized egg outside the uterus.

The study is important, in part, because early bleeding is so alarming to women and yet so little information is currently available to explain what the symptom means for their pregnancy.

"When you have a patient that has bleeding, there's really not a whole lot of data to counsel them with. We hoped to find out: What are the outcomes? What are the complications?" Weiss explains.

"We had thought that when women present to you with bleeding in the first trimester, at least a third would miscarry," adds Dr. Ashi Daftary, medical director of maternal-fetal medicine at Magee-Womens Hospital at the University of Pittsburgh.

The study's more conservative estimate of miscarriage rates may influence the prognosis that doctors convey to their patients, Daftary says.

"This study shows that there's clearly an increase in miscarriage, but the overall risk is relatively low. And once you clear the first trimester, the overall risk is only less than 5 percent," he says.

Daftary notes, however, that one limitation of the study design is that it examined the experience of women close to the end of the first trimester, when vaginal bleeding is usually less problematic. Women who bleed very early in their pregnancy face a much higher risk of miscarriage, with as many as 20 percent losing their pregnancy, he adds.

"The information you'd really like to have is on the women who present even earlier, because they're a very different population of women at higher risk," he says.

The findings were presented at the annual meeting of the Society for Maternal-Fetal Medicine in San Francisco, which ended over the weekend.

More information

For more on early pregnancy bleeding, visit the University of Michigan. For information on high-risk pregnancies, see this.

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