Continuing a pregnancy to at least 39 weeks can cut a newborn's risk of death, even if the mother has carried the pregnancy to term, according to a new study.

In 2006, the infant death rate was 1.9 deaths for every 1,000 live births for babies born at 40 weeks of pregnancy. The death rate increased to 3.9 deaths per 1,000 when a baby was born just a few weeks earlier at 37 weeks of pregnancy, according to the study.

The study shows that even though the death risk is small, it more than doubles for infants born at 37 weeks of pregnancy when compared to babies born at 40 weeks, for all races and ethnicities. The study's results are based off of an analysis of 46,329,018 live births from 1995 to 2006.

Preterm birth is defined as less than 37 completed weeks of pregnancy. Among infants not considered born preterm (at 37 weeks of pregnancy or more), infant death rates were highest for infants born at 37 weeks of pregnancy and declined for each additional week until 40 weeks, which had the lowest infant death rates.

While there are times when medical reasons require a baby to be delivered early , an early elective delivery is usually harmful to a baby and should never be scheduled before 39 or 40 weeks of pregnancy, said researchers from the March of Dimes, the National Institutes of Health and the U.S. Food and Drug Administration.

The study will be published in the June issue of the journal Obstetrics & Gynecology.

Pass it on: Carrying a baby to at least 39 weeks of pregnancy is associated with a lower infant death rate than having a baby at 37 weeks of pregnancy.

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