Elective labor induction has become more common in recent years. This is when labor is induced at term but for no medical reason. Some doctors may suggest elective induction due to a woman's discomfort, scheduling issues, or concern that waiting may lead to complications. But the benefits and harms of elective induction are not well understood. For instance, we do not know if elective labor induction leads to higher or lower rates of cesarean delivery compared to waiting for labor to start on its own. Yet, doctors have ways to assess risk of cesarean delivery, such as a woman's age, whether it is her first pregnancy, and the status of her cervix. Elective induction (not before 39 weeks) does not appear to affect the health of the baby.

If your doctor suggests inducing labor, talk to your doctor about the possible harms and benefits for both mother and baby, such as the risk of c-section and the risk of low birth weight. You will want to be sure the benefits of inducing labor outweigh the risks of induction and the risks of continuing the pregnancy.

​​"Full Term" Has a New Meaning

The meaning of "term" pregnancy has changed. "Term" has been replaced by more specific definitions that communicate the importance of the last few weeks of pregnancy for infant development. Learn why the term pregnancy definitions are important to promoting the best outcomes for mom and baby.

"Full Term" Starts at 39 Weeks

The American College of Obstetricians and Gynecologists and the Society for Maternal Fetal Medicine announced more specific definitions to describe babies born between 37 weeks and 42 weeks of pregnancy.

In the past, a baby born anytime between 37 weeks and 42 weeks was considered "term." A pregnancy is now considered "full term" at 39 weeks.

Why does this matter?

Research shows that babies do best when they are born during weeks 39 and 40.

Babies born before 39 weeks are at risk for problems with breathing, feeding, and controlling their temperature. They are also more likely to spend time in the neonatal intensive care unit, develop infections, and have a learning disability.

What does this mean for my pregnancy?

Waiting to deliver until at least 39 weeks, in a healthy pregnancy, gives your baby the time he or she needs to grow. Your baby's lungs, liver, and brain go through a crucial period of growth between 37 weeks and 39 weeks of pregnancy. Waiting until 39 weeks, now called "full term," gives your baby the best possible chance for a healthy start in life.

There may be a time, if there is a health risk to the mother or baby, when a planned delivery before 39 weeks is necessary. But in a healthy pregnancy, it's best to wait until at least 39 weeks.

It is important to know these terms so you and your health care provider can talk about what is best for the health of you and your baby.

We tend to think of pregnancy as lasting for 9 months. But ideally it should last for nearly 10 months. Research shows that babies are born healthier if they have at least 39 weeks to grow in the womb.

In recent years, there’s been a trend toward earlier deliveries, as more women are choosing the date they’ll give birth. This is known as an elective delivery. Studies suggest that the number of elective deliveries rose dramatically from 1990 to the mid-2000s.

If there’s a particular medical reason to deliver early, then it’s best not to wait, says Dr. Catherine Spong, a pregnancy expert at NIH. “But if the mother and baby are healthy, there’s no benefit to delivering the baby early,” she says. In fact, delivering early can create lasting health problems. Even women of advanced maternal age, older than 35, should wait until at least 39 weeks unless there are medical reasons to deliver early.

“We’ve gotten to the point where people feel they can choose the timing of their delivery,” says Spong. “But in reality, that baby, in the last 4 weeks of pregnancy, is doing a huge amount of developing.”

Those last few weeks can make a big difference. At 39 to 40 weeks of pregnancy, a baby’s brain weighs one-third more than it does at 35 weeks. The lungs and liver also continue to develop up to 39 weeks. And those last few weeks allow time for layers of fat to grow under the baby’s skin, which helps keep the infant warm after birth.

Studies have found a greater risk of serious medical complications—such as dangerous bloodstream infections and breathing and feeding problems—in babies born before 39 weeks of gestation. “While there are risks to every pregnancy, the risks to the baby are higher if all organs are not completely developed,” Spong says.

One NIH-funded study looked at more than 13,000 women who gave birth by elective cesarean delivery (C-section) at 37 weeks or later. The babies delivered at 37 weeks were twice as likely as those born at 39 weeks to have complications—such as difficulty breathing, heart problems and seizures—that usually require time in a neonatal intensive care unit.

Moms who choose to give birth early may also face their own health challenges. They have a greater chance of postpartum (after childbirth) depression; stronger, more frequent contractions during labor; and an increased chance of needing a C-section. Women who have a C-section have a greater risk of infection and a longer recovery time than women who’ve had a vaginal birth.

“Know the true due date of pregnancy and get prenatal care early,” Spong advises.

A woman’s body will go into labor when the baby is ready to enter the world, she says. “By letting that baby get born at term, you’re improving the lifelong health of that baby.”

For a Healthy Pregnancy

• See your health care provider for regular prenatal care.
• Talk to your doctor about the medicines you take. Some may not be safe during pregnancy.
• Follow a healthy diet.
• Take folic acid—at least 400 micrograms each day.
• Stay active. Ask your health care provider about physical activity that’s safe for you.
• Avoid drinking alcohol and smoking.
• Control any existing conditions such as diabetes.
• If there are no medical reasons to deliver early, wait until at least 39 weeks for delivery.

​​​​Let baby set the deliv​​ery date.

• You can avoid or reduce many health risks for the mother and the baby by waiting until 39 weeks of pregnancy to deliver, if there is no medical reason to deliver earlier.
• Research shows that the fetus goes through a significant amount of lung, liver, and brain development between 37 weeks and 39 weeks of pregnancy.
• Your due date could be off​ by up to 2 weeks, which means if you have your baby before 39 weeks you could actually be having it early.
• Research shows that delaying delivery until 39 weeks of pregnancy or later—if there is no medical reason to deliver earlier—is not associated with increased rates of stillbirths​.

Why should I wait until ​​at least 39 weeks of pregnancy to deliver?

• Babies born at or after 39 weeks of pregnancy face fewer health problems.
• Babies' brains, lungs, and liver continue important development until 39 weeks.

What are the risks to my baby and to me if I deliver without a medical reason before 39 weeks of pregnancy?

Risks to the baby:

• May need to stay in the neonatal intensive care unit (NICU)
• Birth complications, including breathing problems and cerebral palsy
• Developmental disabilities, such as attention deficit/hyperactivity disorder (ADHD)
• A 63% greater chance of death within the first year of life compared to babies born between 39 weeks and 41 weeks

Risks to the mother:

• Postpartum depression
• Stronger and more frequent contractions
• Need for a cesarean delivery and its outcomes, including risk of infection, longer recovery time, and the possible need for cesarean delivery in future pregnancies

What questions should I ask​ my health care provider?

• Are there any medical reasons that I might need induced labor before 39 weeks?
• What are the potential complications for my baby of elective induction?
• What are the potential complications for my own health?
• How do you tell when my body is ready for labor?​

Some women may request delivery before 39 weeks of gestation when neither the mother nor the infant is at risk if the pregnancy is allowed to progress. However, research indicates that infants born prior to 39 weeks are at higher risk for more short- and long-term morbidities than those born after 39 weeks. These morbidities are potentially preventable if labor is allowed to begin on its own.

Clinical evidence also shows that a fetus experiences a significant amount of development and growth in several key organ systems between 37 and 39 weeks of gestation.

Delivery prior to 39 weeks is appropriate only if medically indicated and with documented fetal lung maturity, as specified by American College of Obstetricians and Gynecologists (ACOG) guidelines.

In November 2013, ACOG and the Society for Maternal-Fetal Medicine released a committee opinion replacing "term" delivery with new designations based on gestational age. Babies born at weeks 39 and 40 are now considered "full term."

Health Risks to Mother and Infant

Nonmedically indicated deliveries prior to 39 weeks are associated with increased risks to the health of both mother and infant.

• Greater risk of being admitted into the NICU
• 20% greater risk of complications after birth, including:
  • Breathing, feeding, and temperature problems
  • Sepsis
  • Cerebral palsy
• 5% greater risk of developmental disabilities
• 63% greater chance of death within the first year of life

Risks to the mother:

• Postpartum depression
• Stronger and more frequent contractions
• Needing a cesarean delivery, which carries its own risks, including:
  • Increased risk of negative health outcomes for the baby
  • Longer recovery time (weeks rather than days)
  • Risks associated with major surgery, including infection
  • Increased chance that future pregnancies may require cesarean delivery

Recent research findings indicate that delaying delivery until 39 weeks of pregnancy or later—if there is no medical reason to deliver earlier—is not associated with increased rates of stillbirths in the United S​tates. This research, fund​ed by the NICHD and other groups, contradicts findings from an earlier study that waiting until 39 weeks to deliver could lead to more stillbirths.

Healthy first-time mothers whose labor was induced in the 39th week of pregnancy were less likely to have a cesarean delivery, compared to a similar group who were not electively induced at 39 weeks, according to a study funded by the National Institutes of Health. Women in the induced group were also less likely to experience pregnancy-related blood pressure disorders, such as preeclampsia, and their infants were less likely to need help breathing in the first 3 days.

Current guidelines recommend against elective induction of labor — inducing labor without a medical reason — in women in their first pregnancy prior to 41 weeks because of concern of increased need for cesarean delivery. Elective induction at 39 weeks, however, has become more common in recent years. NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) funded this study to determine whether elective induction is beneficial or harmful compared to expectant management (waiting for labor to begin naturally and intervening if problems occur).

More than 6,100 first-time mothers in the NICHD Maternal Fetal Medicine Units Network were randomly assigned to induced labor or to expectant management. Cesarean delivery was less frequent in the induced labor group (19 percent) versus the expectant management group (22 percent). Preeclampsia and gestational hypertension occurred in 9 percent of the induced group and 14 percent of the expectant management group. Among newborns, 3 percent in the induced group needed respiratory support, compared to 4 percent in the expectant management group.

A study found that, for healthy pregnancies, inducing labor after full term (39 weeks) rather than waiting for natural labor doesn’t increase the risk of major complications for newborns.

Being inside the womb for a full 39 weeks is important for a baby’s development. A baby’s brain nearly doubles in size during the last few weeks of pregnancy. The lungs and liver are still developing too.

Once a woman has reached full term, her doctor may suggest inducing labor for different medical, or non-medical, reasons. Sometimes the mother will request an induced labor if she’s uncomfortable in her final weeks.

Prior research has shown that inducing labor before 39 weeks of pregnancy puts the baby at risk of serious health problems. Researchers wanted to find out if inducing labor at full term also puts a baby at risk of serious health problems. They also wondered if it increases a woman’s chance of needing a surgery called a cesarean section, or C-section.

The team enrolled 6,000 pregnant women in the study. Participants were randomly assigned to two groups. Half of the women waited to have a natural labor. The other half were induced at 39 weeks.

The two groups of babies had similar survival rates and chances of serious health problems, such as needing help with breathing, having a seizure, or getting an infection. Inducing labor also reduced the mothers’ chance of a C-section and lowered their blood pressure.

“Induction at 39 weeks should not be routine for every woman, but it’s important to talk with their provider and decide if they want to be induced and when,” says study leader Dr. William Grobman of Northwestern University.