When you’re feeling like a rhino—a rhino with a watermelon sitting on her lady parts—it seems like you’ve been pregnant forever. That’s why it’s always bugged us that the definition of full-term pregnancy is 9 months. With 40 weeks or more spent growing a person, and a little over 4 weeks to a month, we’d like the full credit of 280-plus days, please.

Now the American College of Obstetricians and Gynecologists (ACOG), along with the Society for Maternal-Fetal Medicine, is changing what’s considered full-term. While 37 weeks has been considered full-term up until now, 39 to 40 weeks is the new definition (37 to 38 weeks will now be considered early term). Late term is now 41 to 42 weeks, and the poor unfortunate souls still pregnant past 42 weeks will be classified as postterm.

In recent years, there’s been an effort by the March of Dimes to change the thinking around the idea that your baby’s fully developed by 37 weeks, an assumption that leads to some early non-medical inductions. In fact, we now know that baby’s brains are still growing in the last weeks of pregnancy. Also, babies delivered later feed better and have an easier time regulating body temperature. Inductions also bring an increased risk of c-section, so if medically advisable and barring complications, it’s best to wait for labor to happen on its own.

“[This] is a welcome guideline that eliminates confusion about how long an uncomplicated, healthy pregnancy should last” says March of Dimes Chief Medical Officer Dr. Edward R.B. McCabe. “This new definition acknowledges that the risk of adverse health consequences for babies changes at each stage of pregnancy. Babies born at 39 to 40 completed weeks of pregnancy have the best chance of a healthy start in life.”



Mom of two Sasha Emmons is a writer and editor. Follow her on Twitter and Google+.

A version of this story originally appeared on iVillage.



