Low Level of Amniotic Fluid No Reason to Induce Labor

The condition doesn't jeopardize fetal health, study says

FRIDAY, Feb. 7, 2003 (HealthDayNews) -- A low level of amniotic fluid in the last trimester of a pregnancy, often thought to be sufficient cause to induce delivery, is not reason enough to do so.

Johns Hopkins researchers who studied the health of more than 250 babies born at 37 weeks of gestation say they found that babies whose mothers had low levels of amniotic fluid were of normal size. And the babies had no greater risk for health problems than babies whose mothers had normal levels of amniotic fluid.

"This study indicates that we don't want to intervene because of a Amniotic Fluid Index (AFI) of less than five if everything else is normal," says study author Dr. Ernest M. Graham, an assistant professor of gynecology and obstetrics at Johns Hopkins University.

Graham presented the results of his study on Feb. 7 at the annual meeting of the Society for Maternal-Fetal Medicine in San Francisco.

Amniotic fluid is a clear, slightly yellowish liquid that surrounds the fetus during pregnancy; it is contained in the amniotic sac. Normal levels of fluid indicate proper functioning of the developing fetus, while low levels can be associated with incomplete lung development and poor fetal growth. Measured by depths in centimeters, normal amounts range from five to 25 centimeters; below that is considered low.

The American College of Obstetrics and Gynecology recommends the Amniotic Fluid Index should be only one measure of assessing fetal health. Heart monitors and sonograms are others.

However, doctors often induce delivery -- especially at 37 weeks -- based largely on a low AFI, says Dr. Siobhan Dolan, assistant medical director of the March of Dimes.

Normal gestation lasts approximately 37 to 40 weeks, according to the March of Dimes, which last week launched a $75 million campaign to address the high incidence of premature babies born before 37 weeks.

"In general, there's a tendency, at 37 weeks, to deliver the baby," Dolan says. "But this is a good study because it gives people reassurance to manage the pregnancy with careful monitoring and observation. You don't have to go immediately to the labor room."

For the study, Graham and his colleagues studied 262 women who gave birth at Johns Hopkins Hospital from 1999 to 2002, comparing the babies' health at birth. One hundred thirty-one women had had a low AFI during their third trimester, a condition called oligohydramnios. The other 131 women had normal amounts of amniotic fluid at the end of their pregnancies.

Women with low AFI levels had their labor induced sooner due to their condition, but were less likely to have Caesarean sections, Graham says. The babies born to these women were normal size, and were at no increased risk for respiratory problems, immature intestines or brain disorders, he says.

"We've always thought that AFI was correlated with blood flow in the fetus, that a low AFI meant there wasn't a good blood flow, but we found that AFI is a very poor indicator of that," Graham says. The finding should give doctors pause before using AFI test results as a reason to induce delivery, he adds.

"If a low AFI is the only thing determining an early intervention in a pregnancy, that is not a reason to do so," he says.

More information

An explanation of the fetal monitoring tests used during pregnancy, including AFI readings, can be found at the University of Michigan Health System. The March of Dimes describes what amniotic fluid is and why it is important to the development of the fetus.

Related Stories

No stories found.
logo
www.healthday.com