It's well known that babies born prematurely are at increased risk of slowed brain development, but according to a new study, published in the journal Pediatrics on Monday, babies born even a few weeks early are at a similar risk. (Photo: Creative Commons)

It's well known that babies born prematurely are at increased risk of slowed brain development, but according to a new study, published in the journal Pediatrics on Monday, babies born even a few weeks early are at a similar risk.

A "normal" birth term is between 37 and 41 weeks, researchers said, but babies born towards the lower end of that range scored lower on math and reading tests when they were 8 years old than babies born later. They stress, however, that the difference is small but noticeable.

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"Certainly the vast majority of 37-weekers and 41-weekers would end up developing typically," Kimberly Noble, the lead author on the study from Columbia University Medical Center and New York-Presbyterian Hospital, told Reuters.

However, until more research is done, "we would urge caution to both parents and physicians when considering early elective delivery," she said.

Noble and her team compared birth records and scores from standardized tests of almost 130,000 New York City students and found those born at 41 weeks scored approximately one point higher, out of 50, than those born at 37 weeks. This translates to a 1.5 point IQ difference, researchers said.

"That would not be a difference that would likely be noticeable from one child to the next," she said. "Where it is more noticeable is on the lower end of the (test score) distribution."

Children born at 37 weeks were also 23 percent more likely to have a moderate reading impairment and 19 percent more likely to have a math impairment, researchers said.

While expectant mothers should not worry if their child is born at 37 weeks rather than 40, researchers said the key is to not force the baby to come out earlier than it is prepared to, such as the case in planned C-sections.

"The main thing is when you're coming to the discussion about delivery and if you have a decision about the timing of that delivery, to really make sure that you're as far along in pregnancy as you can get without getting out of the range of normal," Marie McCormick, a maternal and child health researcher from the Harvard School of Public Health in Boston, told Reuters.