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Waiting 18 Months Between Pregnancies Reduces Risk of Preterm Birth

A recent study finds that getting pregnant less than 18 months after giving birth increases the risk of preterm delivery.

"The most significant [birth] risks are associated with the shortest birth intervals," says Dr. Emily DeFranco, lead researcher and professor at University of Cincinnati.

DeFranco looked at 454,716 Ohio Department of Health birth records of moms who had given birth at least twice within six years. She concluded that women who conceived again within a year of giving birth were two times as likely to deliver prematurely, which is before 39 weeks' gestation. Waiting 18 months after giving birth to conceive greatly reduced that risk. DeFranco's findings were published in the "International Journal of Obstetrics and Gynaecology."

"Preterm birth increases the risk of newborn death within the first four weeks of life, is associated with learning delays and affects the development of lungs and organs," says Dr. Francis Chang, an OB/GYN at Good Samaritan Hospital in Los Angeles. "If you can prevent these risks from happening, obviously that's better."

And when it comes to time in utero, every day counts. Dr. Chang says there's a difference in time spent in the NICU even for a baby born at 38 weeks and 6 days versus a baby born at 39 weeks.

One in eight babies in the United States is born before 37 weeks of pregnancy, according to the Centers for Disease Control and Prevention.

Dr. Chang acknowledges that couples must weigh several factors when deciding to get pregnant again.

"This is another piece of data in the decision pool," he says. "For example, 40-year-old parents are thinking about declining fertility. Getting pregnant in the first place can be difficult. It's all about counseling on an individual basis. But the risk of preterm delivery must be part of the equation."

Other factors in addition to birth spacing also influence a woman's risk of preterm delivery, such as smoking, age and income. To understand your risk, go to the March of Dimes website.