THURSDAY, June 5, 2014 (HealthDay News) -- Women who wait less than 18 months after having a child to get pregnant again are more likely to have a shorter pregnancy and a preterm birth, according to a new U.S. study.
The study authors recommended that women be educated about the importance of "birth spacing" to help reduce rates of premature births and the associated health problems.
"This study has potential clinical impact on reducing the overall rate of preterm births across the world through counseling women on the importance of adequate birth spacing, especially focusing on women known to be at inherently high risk for preterm birth," said study co-author Emily DeFranco, an assistant professor of maternal-fetal medicine at the University of Cincinnati College of Medicine.
For the study, the researchers examined Ohio Department of Health records for nearly 455,000 births to see how birth spacing -- the amount of time between giving birth to one child before becoming pregnant again -- affected the duration of pregnancy.
The women in the study had two or more pregnancies within six years. Those with a short amount of time between birth and another pregnancy were divided into two groups: those who waited less than 12 months before becoming pregnant again and those who waited 12 to 18 months. These women were then compared to women who waited 18 months or more between pregnancies.
The study found that women with shorter times between pregnancies were more likely to give birth before reaching 39 weeks' gestation than women who waited longer. Overall, women who waited at least 18 months between pregnancies had the lowest rates of premature birth.
Of the women who had less than 12 months between pregnancies, just over 53 percent delivered before 39 weeks' gestation. These women were also more than twice as likely as women who waited 18 months or more between pregnancies to deliver before 37 weeks' gestation.
The study authors said they also found that black women more often had shorter intervals between pregnancies than other women. Premature deliveries were also more common among black women who waited less than 12 months between pregnancies. However, overall, black women had higher rates of premature deliveries -- even when there was 18 months or more between pregnancies. The researchers concluded that a woman's race might be a predictor of premature birth, regardless of birth spacing.
The study was published June 4 in BJOG: An International Journal of Obstetrics and Gynaecology.
"We know that inadequate birth spacing is associated with more adverse pregnancy outcomes, including preterm birth, in many countries like the U.S.," John Thorp, BJOG's deputy-editor-in-chief, said in a journal news release. "This large population-based study further strengthens this and puts more emphasis on the importance of optimal birth spacing, of 18 months or more, especially among women with additional risk factors for preterm birth."
According to the U.S. Centers for Disease Control and Prevention, preterm birth -- before 37 weeks' gestation -- affects nearly 500,000 babies every year. That's one of every eight infants born in the United States. Some problems that a baby born too early may face include: breathing and feeding difficulties, cerebral palsy, developmental delays, and hearing and vision problems.
For more on preterm births, visit the U.S. Centers for Disease Control and Prevention.
SOURCE: BJOG: An International Journal of Obstetrics and Gynaecology, news release, June 4, 2014
-- Mary Elizabeth Dallas
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