While a woman can't be a little bit pregnant, expectant mothers now can be a little bit due.

That's because medical societies overseeing such matters redefined a full-term pregnancy as a series of stages instead of the previous single definition. The previous definition might have been misleading people into thinking that early-term inductions are OK, when they're not. Research shows that babies are healthiest when born in the two weeks beginning at 39 weeks of pregnancy.

So, the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine created four stages of a term pregnancy, a declaration that should make it easier for hospitals to enforce labor-induction standards designed to improve health. The four stages are early term, full term, late term and post-term.

"This terminology change makes it clear to both patients and doctors that newborn outcomes are not uniform even after 37 weeks," says Jeffrey Ecker, M.D., chair of the college's Committee on Obstetric Practice, in a news release. "Each week of gestation up to 39 weeks is important for a fetus to fully develop before delivery and have a healthy start."

For that reason, Ecker says that planned deliveries before 39 weeks' gestation should occur only when there is significant health risks to the baby or fetus.

The change will be good news for my wife, who works as a certified nurse midwife and has long been an advocate of allowing pregnancies to go to full term when possible.

ACOG and systems such as Touro Infirmary already have made strides in reducing elective inductions before the 39-week milestone has been hit. Nearly two-thirds of hospitals with labor and delivery units instituted policies to eliminate elective deliveries before 39 weeks of gestation, according to survey results presented in May.

The new definitions give hospitals and physicians the support needed to convince pregnant women to shoot for the two-week period that is healthiest for the baby. And use of the phrase "early term" for births in the period from 37 weeks to 38 weeks and 6 days of gestation rightly implies that the preference would be to go a little longer with the pregnancy.

While expectant mothers are often eager to welcome the baby into the world, the new classifications should discourage unnecessary labor inductions and give providers and researchers better data to improve outcomes. That sounds like a strong move in the right direction, even if it does complicate the answer to the question, "When are you due?"

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