TUESDAY, Oct. 18 (HealthDay News) -- Hurricane Katrina's devastating effects six years ago appear to have extended beyond the Gulf Coast, with miscarriages and premature births among fertility patients rising markedly across the United States in the months after the disaster.

Researchers tracked outcomes for nearly 105,000 single-baby pregnancies among women who had undergone assisted reproductive technology (typically in vitro fertilization) across the country before and after the storm hit in August 2005.

The team found that pregnancies begun in the 18 months before the calamity were 87 percent less likely to end in a first-trimester miscarriage, compared to ART-assisted pregnancies initiated after the storm.

Pregnancies that began in the months and weeks before Katrina were also significantly less likely to result in extreme prematurity -- babies born before 26 weeks of gestation -- than conceptions occurring after the event.

After adjusting for other contributors to poor pregnancy outcomes, including patient age, infertility diagnosis and sperm source, the researchers also found that fertility patients across the United States were 63 percent less likely to suffer a miscarriage within the first four months of a pregnancy if their pregnancies had begun before Hurricane Katrina rather than after.

Stress may be the key here, experts said.

"We in the infertility field have always been concerned about the effects of stress or grief on reproductive success," said Dr. Mary Wood-Molo, medical director of the Center of Advanced Reproductive Care at Rush University Medical Center in Chicago, who was not involved in the study. "On some level I'm not surprised by this . . . with media exposure that continued to focus on the crisis and aftermath, it became more of a national crisis than a local crisis."

The findings, from data compiled by the Society for Assisted Reproductive Technology, are scheduled to be presented Oct. 19 at the annual meeting of the American Society for Reproductive Medicine in Orlando, Fla. Studies presented at scientific meetings are preliminary and have not undergone peer review.

Study authors were surprised that the pregnancy loss rate among those analyzed was the same across the country, not just in the areas affected by the storm.

Adding to the puzzle was the fact that the pregnancy failure rate remained the same pre- and post-Katrina in those counties directly affected by the hurricane.

Study lead author Sangita Jindal said that finding likely stems from other factors. "In the Gulf area, there was already an elevated preterm delivery rate and Katrina didn't affect that," noted Jindal, an assistant professor of obstetrics/gynecology and women's health at Montefiore Medical Center and Albert Einstein College of Medicine in Hartsdale, N.Y. "I'm not sure what causes that compared to the rest of the country, but perhaps there are population disparities."

Wood-Molo and Jindal agreed that infertility patients endure so much stress trying to become pregnant and carry babies to term that the additional stressor of a natural disaster can make them more susceptible to poor outcomes.

"These women may or may not have underlying metabolic or physical issues related to their infertility," Jindal said, "so as a population they may be more sensitive . . . and may not be as robust. So when they get pregnant, it's a little more tenuous."

More information

There's more on infertility treatment at the U.S. Centers for Disease Control and Prevention.