Posted May 19, 2009
By Thomas H. Maugh II
Los Angeles Times
Taking folic acid supplements for a year before conception reduces the risk of premature birth by at least 50 percent, researchers reported last week.
Shorter courses of the supplement were not as effective, according to a study of nearly 35,000 women that was reported in the journal PLoS Medicine.
“We have known for a long time that folic acid will reduce the risk of neural tube defects” and other birth defects, but the discovery that it also can reduce the risk of pre-term birth “is very significant,” said Dr. Diane Ashton, deputy medical director of the March of Dimes Birth Defects Foundation, who was not involved with the study.
The finding, she added, reinforces the recommendation that “all women of childbearing age should take multivitamin supplements.”
Only 35 percent to 40 percent of women in that age group do take supplements, according to surveys by the March of Dimes and other groups.
Pre-term births account for about 12 percent of all deliveries in the United States and are associated with vision impairment, mental retardation and cerebral palsy in children, as well as diabetes and cardiovascular disease later in life. The earlier the delivery, the higher the risk of complications.
The new study was conducted because earlier research had shown that women who delivered prematurely tended to have lower-than- normal levels of folate in their blood. Previous small trials of folic acid supplements to prevent premature birth had mixed results.
Dr. Radek Bukowski and colleagues at the University of Texas Medical Branch at Galveston were able to screen a much larger number of women by piggybacking their research onto a National Institutes of Health study testing methods of screening for Down syndrome.
“It was such a large data set, with so much information, that we were able to answer this question as well,” Bukowski said.
The women were questioned during the first trimester of pregnancy about their health behaviors, including use of supplements. Time of conception was documented accurately by ultrasound examination.
The researchers found that for women who had been taking folate for at least a year before conception, the risk of birth between 28 and 32 weeks of gestation was reduced by 50 percent. (Full-term delivery occurs at 38 to 40 weeks.) The risk of birth between 20 and 28 weeks was reduced by 70 percent.
The latter reduction was particularly noteworthy, Ashton said, because delivery before 28 weeks has accounted for about 2 percent of pre-term births for decades and researchers had found no way to reduce the percentage.
“A 70 percent reduction is very significant,” she said.
The supplementation appeared to have no effect on the risk of pre- term birth after 32 weeks, the researchers found. Although beginning supplementation around the time of conception reduced the risk of neural tube defects, it did little to reduce pre-term births.
The United States has required flour and other grain-based products to be fortified with folic acid since 1998.
Additionally, health authorities recommend that women of childbearing age – regardless of whether they intend to become pregnant – supplement their diets with 400 micrograms of folic acid every day. There has been recent debate about whether higher doses would be more beneficial.
Some critics say higher doses could mask other dietary deficiencies.
The latest study, Bukowski said, suggests that “dose is not as important as duration.”
the danger
Pre-term births account for about 12 percent of all deliveries in the United States and are associated with vision impairment, mental retardation and cerebral palsy in children, as well as diabetes and cardiovascular disease later in life. The earlier the delivery, the higher the risk of complications.
Date: May 17, 2009
