How many weeks is a “full-term pregnancy”?
In October 2013, the American College of Obstetricians/Gynecologists (ACOG) issued an updated definition for term pregnancies. The updated definitions are significant because they change when pregnancies are classified as “full term.”
Prior to the new definition, a pregnancy was deemed full term from three weeks before to two weeks after a woman’s due date; that is, a full term pregnancy ranged from 37-42 weeks. It was thought that babies born in this window all performed equally well and had the same level of risk for complications.
Based on newer global data, however, we now know that this isn’t the case. Babies born between 39 and 41 weeks have the least amount of complications, whereas babies born earlier and later than that have some increased risks. This is what has led ACOG to adjust their terminology.
Pregnancies should now be defined as follows:
- Early term: 37 weeks through 38 weeks
- Full term: 39 weeks through 40 weeks
- Late term: 41 weeks
- Postterm: 42 weeks and late
The goal of the new definitions is to help patients and doctors understand that babies who are not yet 39 weeks still have developing and maturation to do—and that is best done in the womb.
Elective deliveries for non-medical reasons, like a doctor going away on vacation or a parent wanting a certain birthday, are not appropriate before the 39-week mark. While that is not a new concept, ACOG hopes that labeling these babies as early term will discourage elective early deliveries.
Reviewed by Dr. Jen Lincoln, December 2018
Takeaways
- Full term pregnancies used to include babies born at 37-42 weeks gestation.
- Babies born between 37-39 weeks of pregnancy are now called early term.
- Babies who are not yet 39 weeks still have developing to do inside the womb.
- Early term babies should not be delivered unless there is a medical indication.
I was delivered at least a month early (possibly 6 weeks) via C-section because my mom developed pre-eclampsia. She was a bit scared because my great-aunt died of pre-eclampsia when she was 18, though of course back then medical care wasn’t as advanced, not to mention her doctor was an idiot who insisted she was fine. Thankfully her baby survived (born the day after New Year’s), but she died later on Valentine’s Day, exactly 2 months before her 19th birthday.
I’m glad there’s a new set of terms! Around the 37 week mark in my pregnancy, people started asking me if I was setting a date for the baby to be born. I can’t quite wrap my head around the concept of delivering a baby before it’s ready to thrive outside the womb! I know it might be easier for working moms to be able to plan their maternity leave, but I think it’s so much healthier for the baby to let it happen when it happens. I can understand medical reasons for early delivery but not elective.
I gave birth at 41w2d so I guess I was “later term,” and although I was miserable at the time I’m very glad it happened that way looking back! My little girl was thankfully very healthy at birth. She came on her own two days before they were planning on inducing me.
Both of my babies were delivered early via c-section. I developed high blood pressure with both pregnancies so my doctor felt it was best to take the babies when they did (my first at 38 weeks and my second right at 37 weeks). My second was much smaller. What a difference a week makes.
I went into labor on my due date! It made me remember that we don’t need to control everything, our bodies know what they are doing!
I went into labor naturally at 39w1d. My doctor had me scheduled to be induced at 39w3d. I was soooo happy to go into labor naturally because I had fought with my doctor the entire pregnancy to not be induced. I’m Diabetic (Type 1), so she wanted me to deliver before 40w. I understand her reasons, but it was important for me to let my little guy “cook” as long as he needed to! I’m just really happy he decided he was ready before my doctor made the decision for him!
That’s great you went into labor on your own and got to avoid an induction, especially since Type 1 diabetes is definitely a legitimate reason to induce – isn’t that nice when babies get the memo?? Congrats!