SAN FRANCISCO, July 12 (UPI) -- Preterm birth of a second child is significantly more likely if a woman's first child was born early, according to research.
Researchers at the University of California San Francisco found that if a woman's first child is born early between 37 and 38 weeks of gestation, it increases the chance by two or three times for her second child to be born preterm, before 37 weeks of gestation.
Previous research has shown premature birth is more likely among women with hypertension or diabetes, as well as black women, women who have become pregnant less than six months after a previous pregnancy or who have used illicit drugs while pregnant.
Even with other known risk factors considered, researchers say it can be difficult to identify women at greater risk for early-term or preterm birth but that statistics in the new study show an increased likelihood for certain women to go into labor early, suggesting some should be flagged as at risk even absent those factors.
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"Delaying labor by just two weeks could make a major difference in neurologic outcomes and adult health," Dr. Larry Rand, an associate professor of obstetrics, gynecology and reproductive sciences at the University of California San Francisco, said in a press release.
For the study, published in the journal Obstetrics and Gynecology, researchers reviewed medical records for 163,889 women who delivered their first and second single pregnancy children between 2005 and 2011.
Of all first pregnancies in the study, 5.7 percent of women gave birth preterm, which would make them considered to be at high risk for another preterm birth, though researchers report 22 percent gave birth early-term, defined as 37 or 38 weeks, and would not receive extra care and attention to prevent a second early birth.
The researchers say expanding the number of women targeted for intervention could reduce the risk of early birth, with closer monitoring of the cervix and early contractions for signs of labor, with progesterone or other medical treatment used to slow or stop labor.
"We are on the edge of a new era in prematurity prevention and improving associated outcomes -- there are new blood tests that can help improve identifying who's at risk for prematurity," Rand said. "When coupled with important risk factors, like maternal conditions and previous pregnancy duration, not only do we get a more precise picture of risk, but also a more informed sense of what interventions could be most powerful to mitigate those risks."
