What Is Full Term? Why Is It An Important Milestone?

Pregnancy isn’t a sprint, it’s a marathon. It lasts even longer than you might think, and towards the end most moms are ready to be done! And with celebrities inducing and scheduling birth at 37 weeks, it’s easy to become confused about what is full term. If so many women give birth at 37 or 38 weeks pregnant, why can’t you?

Well, there are plenty of reasons to slow down and trust your body’s timing. In this article, we’ll unpack them all, including:

• What is full term?
• Why are full term birth guidelines so important?
• What happens if you go past your due date?

What Is Full Term?

Prior to 2013, full term was considered any date after 37 weeks. But the American Congress of Obstetricians and Gynecologists (the “ACOG”) revised those guidelines in October of 2013.

Now the last few weeks of pregnancy are divided into various stages. 

• Early Term: 37 weeks to 38 weeks, 6 days
• Full Term: 39 weeks to 40 weeks 6 days
• Late Term: 41 weeks to 41 weeks 6 days
• Post Term: 42 weeks and beyond

Why Are These Guidelines So Important?

These guidelines don’t exist just to reassure you that, yes, you won’t be pregnant forever. They leave no question about what is full term.

When full-term was 37 weeks, experts say it led to too many elective inductions before 40 weeks. This was problematic for the health of both baby and mama. Let’s take a closer look at why:

For baby’s health

You may be ready to be done with pregnancy, but those final weeks are critical for baby’s…

• Brain function: Baby’s brain is still growing; it almost doubles between 35 and 39 weeks!
• Lung development: Baby’s lungs may not be fully developed at 37 weeks. In one study, even when it had been determined that the babies had reached fetal lung maturity, many still had many respiratory problems when delivered before full term.
• General well-being: Babies delivered electively at 37 weeks have a 4.9 percent likelihood of ending up in the neonatal intensive care unit versus a 2.5 percent chance among full-term babies. Babies delivered early are also more likely to need IV fluids or IV antibiotics. (source)

For mama’s health

Even though those last few weeks are trying, making it to full term is important for mama, too. Early delivery increases the risk of…

• C-section: When induction occurs before full-term, it fails 25 percent of the time. Failed inductions often lead to C-sections.
• Adverse health conditions: One study suggests women who deliver at 34 weeks have a greater risk of hemorrhaging, needing a blood transfusion, and other postpartum complications.

Of course, there are exceptions…

Sometimes the risk of remaining pregnant—like if mama has preeclampsia or gestational diabetes—outweighs the risks of inducing labor or delivering by C-section.

If there’s any concern about your ability to carry baby to term, your healthcare provider will work with you closely as you near the end of your pregnancy to determine what’s right for you.

What Happens If You Go Past Your Due Date?

For a long time, practitioners were concerned about babies growing too big for mom’s pelvis or the placenta growing too old to sustain the baby. While those things do occasionally happen, it’s rare.

Cephalopelvic disproportion (“CPD”), the medical term for when the baby’s head is too big for mom’s pelvis, for example, only occurs in 1 out of 250 pregnancies. That equates to less than a .4 percent chance.

The new guidelines clearly answer the question what is full term and send the message that it’s normal for baby to be late—that a due date is just an estimate. (Read more about why in this post on dating pregnancy. You can also find out how accurate your due date is in this post.) And now many practitioners understand that there’s a two week window after 40 weeks where baby can still safely remain in utero.

What Happens If You Go Past 42 Weeks?

Only about 1 out of every 10 babies is officially overdue (born after 42 weeks of pregnancy).

But if pregnancy does go past 42 weeks, a baby has an increased risk of certain problems, such as dysmaturity syndrome, macrosomia, or meconium aspiration. According to ACOG, there also is an increased chance of cesarean birth.

If you’re approaching 42 weeks, your midwife or doctor will monitor you very closely. They may try natural induction techniques, encourage kick counts, and even recommend a non-stress test.

Remember…

The date you get from a due date calculator or via an ultrasound is an estimate—don’t chisel that day in stone! Trust your body’s timing, and know that there is medical consensus on what is full term. Even if you’re growing tired of being pregnant, work with your healthcare provider during those final weeks to ensure the best possible labor and delivery for both mama and baby.