Giving Birth Before Your Due Date: Do All 40 Weeks Matter?

You may be eager for the nine months to end, but a little patience can deliver big benefits. Understand the positive impact a full term pregnancy can have on your baby's health.

Your due date is in sight and you only have a few weeks to go. In fact, you're so close, you'd be happy to get the show on the road and have your baby now. What's the harm? Your doctor told you, after all, that at 37 weeks, you're close enough to your due date that it's safe to have your baby. That's what countless women were told during the 80s, 90s and 2000s when the induction craze was at its peak.

As it turns out, those last few weeks are just as important as any other phase of pregnancy, and "close enough" doesn't always cut it. Experts now believe that you should do everything in your power to make it to your due date, unless there's a medical reason to deliver your child sooner. That's because research suggests that birthing a baby prior to 39 weeks puts him at higher risk for a range of health and developmental problems. "The evidence is so compelling that a growing number of American hospitals are launching programs to help prevent elective deliveries before 39 weeks of gestation," says Diane Ashton, M.D., deputy medical director of the March of Dimes.

What is Term Pregnancy?

The American Congress of Obstetricians and Gynecologists has redefined the meaning of "term pregnancy." Pregnancies used to be considered at term, and babies ready for delivery, any time after 37 weeks. Most physicians believed that major organ development was complete at this time and that babies simply packed on pounds during the last stretch of pregnancy. If mom went past that, those last three weeks (or longer) were almost seen as a write-off.

Now, however, after a couple of decades that have seen too many C-sections and record numbers of babies in the neonatal intensive care unit (NICU), those last few weeks of pregnancy are being taken seriously. "We now know that important organs, such as the lungs and the brain, are not fully developed until 39 weeks," says Jason K. Baxter, M.D., an Ob-Gyn who specializes in high-risk pregnancies at Thomas Jefferson University Hospital, in Philadelphia.

"Term pregnancy" is now being broken down into distinct categories.

  • Early Term: Between 37 weeks 0 days and 38 weeks 6 days
  • Full Term: Between 39 weeks 0 days and 40 weeks 6 days
  • Late Term: Between 41 weeks 0 days and 41 weeks 6 days
  • Postterm: Between 42 weeks 0 days and beyond

Babies Born at 37 Weeks

Doctors and hospitals have learned so much from the mistakes made back in the day when inductions and C-sections were as easy to schedule as a haircut, and were often done with mothers who were only 37 - 38 weeks pregnant. Many of these procedures were done not out of medical necessity, but for convenience sake – for example, to make sure grandma could be at the birth, or so mom could be sure her own doctor would be on-call during her labor.

But because due dates are often miscalculated, especially by ultrasound, doctors were frequently delivering premature babies who wound up spending time in the NICU. One study, for example, found that babies born by C-section before 39 weeks have more breathing difficulties than babies delivered by C-section after 39 weeks. Furthermore, babies delivered electively at 37 weeks are four times more likely to end up in the neonatal intensive care unit or have serious respiratory troubles than babies born at 39 weeks or later; babies who arrive at 38 weeks are twice as likely to have complications.

Additionally, many of the inductions were unsuccessful because mom's body was not ready to go into labor. These women wound up with C-sections they most likely wouldn't have needed if they'd waited for labor to start on its own.

Why Those Last Weeks Matter

You may be tempted to ask your doctor for an early induction because of swollen ankles or an aching back, but that final month is critical to your baby's good health. For starters, a compound in her lungs called surfactant, which enables her to breathe independently, continues to be produced in greater amounts during the last month of pregnancy and decreases her risk of developing breathing problems once she arrives.

Her liver is still undergoing changes that will enable it to properly filter toxins, such as jaundice-causing bilirubin, out of her body. Her skin is thickening and she is accumulating more body fat, which will help her to maintain her own body temperature after she's born. Brain development is still underway; at 35 weeks, for example, its volume is only about two thirds of what you'd expect at 39 to 40 weeks, says Dr. Ashton. Additionally, important brain and nerve connections are being made to help her suck, swallow, breathe, regulate her body temperature, and even sleep better once she's born.

The Importance of Full-Term Baby Birth

Slowly but surely the birth culture of "induction or C-section on demand" has changed. Now, most doctors have received the memo that unnecessary inductions are potentially dangerous for moms and babies. If there are solid, compelling medical reasons to induce or schedule a C-section, then, by all means, that's what those procedures are there for. However, if the medical reason can wait until a baby is full term, mothers and babies both fare better.

Another great thing about these guidelines is that it spells out that a woman isn't really "over due" when she goes past her due date a week or two. For a long time now, doctors have been fixed on that 40-week mark as if a timer will go off and all hell's going to break loose if the baby isn't born lickety-split. Their concern is about babies growing too big for mom's pelvis, or a placenta growing too old to sustain a baby. While those things do occasionally happen, they don't happen very often. Since post due date pregnancies put doctors on the defense (legally speaking) however, the birth culture pressed hard for women to accept medical interventions to push them into labor once the buzzer went off.

The thing is that prior to when all those crazy inductions took over the birth industry in the 80s and well into the 2000s, women delivered safely a week or two past their due dates all the time and it was no big deal. Sure, they were crazy uncomfortable and frustrated, but nobody considered that there was anything wrong with them.

These new guidelines send the message that women and their doctors need to hear: So what if the baby's a little late? No biggie. He or she will come when really, truly ready to be born. Frankly, we think mom's body knows when that time is far better than anybody else.

Updated by Jennifer L. W. Fink
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