Labor and Delivery

The primary sign of labor is a series of contractions (tightening and relaxing of the uterus) that arrive regularly. Over time, they become stronger, last longer, and are more frequent. Some women may experience false labor, when contractions are weak or irregular or stop when the woman changes positions. Women who have regular contractions every 5 to 10 minutes for an hour should let their health care provider know.

It is important to discuss labor and signs of labor with a health care provider early in pregnancy, before labor begins. Some providers may want a woman to wait until she has multiple signs of labor or is in "active" labor before coming to the hospital or birthing center.

Other signs of labor include:²

• "Lightening." This term refers to when the fetus "drops," or moves lower in the uterus. This may happen several weeks or only a few hours before labor begins. Not all fetuses drop before birth. Lightening gets its name from the feeling of lightness or relief that some women experience when the fetus moves from the rib cage to the pelvic area. It allows some women to breathe more easily and more deeply and may provide relief from heartburn.
• Increase in vaginal discharge. Called "show" or "the bloody show," the discharge can be clear, pink, or slightly bloody. This discharge occurs as the cervix begins to open (dilate) and can happen several days before labor or just as labor begins.

Labor contractions before 37 weeks of pregnancy are a sign of preterm labor. Women who notice regular, frequent contractions at any point in pregnancy should notify a provider or go to the hospital. Providers can check for changes in the cervix to see whether labor has begun. As needed, providers can also give women in preterm labor specialized care. Among women who experience preterm labor, only about 10% go on to give birth within a week.

Other signs of labor include:³

• Change in vaginal discharge
• Pain or pressure around the front of the pelvis or the rectum
• Low, dull backache
• Cramps that feel like menstrual cramps, with or without diarrhea
• A gush or trickle of fluid, which is a sign of water breaking

Sometimes, if the health of the mother or the fetus is at risk, a woman's health care provider will recommend inducing or causing labor using medically supervised methods, such as medication.⁴

Unless earlier delivery is medically necessary or occurs on its own, waiting until at least 39 weeks before delivering gives mother and baby the best chance for healthy outcomes. During the last few weeks of pregnancy, the fetus's lungs, brain, and liver are still developing.⁵

The Is It Worth It? Initiative, from NICHD's National Child and Maternal Health Education Program, focuses on raising awareness of the importance of waiting until at least 39 weeks to deliver a baby, unless it is medically necessary to deliver earlier.

Induction is usually used only when a problem with the pregnancy risks the health of either the mother or the fetus or when the due date has passed.²

Several weeks before labor begins, the cervix begins to soften (called "ripening"), thin out, and open to prepare for delivery. If the cervix is not ready, especially if labor has not started 2 weeks or more after the due date, a health care provider may recommend medication or other means to ripen the cervix before inducing labor.

Health care providers use a scoring system, called the Bishop score, to determine how ready the cervix is for labor. The scores range from 0 to 13. A score of less than 6 means that the cervix may need help to prepare for labor.¹

If the cervix is not ready for labor, a health care provider may suggest one of the following steps to ripen the cervix:^1,2

• Stripping the membranes. The health care provider can separate the thin tissue of the amniotic sac, which contains the fetus, from the wall of the uterus. This process causes the body to release prostaglandins (pronounced pros-tuh-GLAN-dins), which soften the cervix and cause contractions.
• Giving prostaglandins. This drug may be inserted into the vagina or given by mouth. The body naturally makes these chemicals to ripen the cervix, but sometimes additional amounts are needed to help labor occur.
• Inserting a catheter. A small tube with an inflatable balloon on the end can be placed in the cervix to widen it.

Once the cervix is ripe, a health care provider may recommend one of the following techniques to start contractions or to make them stronger:¹

• Amniotomy (pronounced am-nee-OT-uh-mee). A health care provider uses a tool to make a small hole in the amniotic sac, causing it to rupture (or the water to break) and contractions to start.
• Giving oxytocin (also called Pitocin). Oxytocin is a hormone the body naturally makes that causes contractions. It is given to start labor or to speed up labor that has already begun.

In most cases, induction is limited to situations in which there is a problem with the pregnancy or in which the pregnancy has continued past the infant's due date. It is usually best to "let the baby set the delivery date" and allow labor to begin on its own, unless there is a medical reason to do otherwise.

Women who want labor induction for non-medical reasons should discuss it with their health care providers.^2,3

Pain-relief drugs fall into two categories: analgesics (pronounced an-uhl-JEE-ziks) and anesthetics (pronounced an-uhs-THET-iks).¹

Each category has different forms of medications. Some of these medications carry risks. It is important for women to discuss medications with their health care provider before going into labor to ensure that they are making informed decisions about pain relief.

Analgesics

Analgesics relieve pain without causing total loss of feeling or muscle movement. These drugs do not always stop pain completely, but they reduce it.

• Systemic analgesics affect the whole nervous system rather than a single area. They ease pain but do not cause the patient to go to sleep. Systemic analgesics are often used in early labor. They are not given right before delivery, because they may slow the baby's breathing and reflexes. They are given in three ways:
  • Injected into a muscle or vein
  • Administered through a small tube placed in a vein. The woman can often control the amount of analgesic flowing through the tube.
  • Inhaled or breathed in with a mixture of oxygen.² The woman holds a mask to her face, so she decides how much or how little analgesic she receives for pain relief.
• Regional analgesics relieve pain in one region of the body. In the United States, regional analgesia is the most common way to relieve pain during labor.³ Several types of regional analgesia can be given during labor, so you should discuss your options with a health care provider before your due date. Examples include (but are not limited to) the following:
  • Epidural analgesia, also called an epidural block or an epidural, causes loss of feeling in the lower body while the patient stays awake. The drug starts working about 10 minutes to 20 minutes after it is given. A health care provider injects the drug near the spinal cord. A small tube (catheter) is placed through the needle. The needle is then withdrawn, but the tube stays in place. Small amounts of the drug can then be given through the catheter throughout labor without the need for another injection.
  • A spinal block is an injection of a much smaller amount of the drug into the sac of spinal fluid around the spine. The drug starts working right away, but it lasts for only 1 to 2 hours. Usually, a spinal block is given only once during labor, to help with pain during delivery.

Anesthetics

Anesthetics block all feeling, including pain.

• General anesthesia causes the patient to go to sleep. The patient does not feel pain while asleep.
• Local anesthesia removes all feeling, including pain, from a small part of the body while the patient stays awake. It does not lessen the pain of contractions. Health care providers often use it when performing an episiotomy (pronounced uh-pee-zee-OT-uh-mee), a surgical cut made in the region between the vagina and anus to widen the vaginal opening for delivery or when repairing vaginal tears that happen during birth.

Women who choose natural childbirth rely on a number of ways to ease pain without taking medication. These include:^4,5,6

• The company of others who offer reassurance, advice, or other help throughout labor, also known as continuous labor support^7,8
• Relaxation techniques, such as deep breathing, music therapy, or biofeedback
• A soothing atmosphere
• Moving and changing positions frequently
• Using a birthing ball
• Massage
• Yoga
• Taking a bath or shower
• Hypnosis
• Using soothing scents (aromatherapy)
• Acupuncture or acupressure
• Applying small doses of electrical stimulation to nerve fibers to activate the body's own pain-relieving substances (called transcutaneous electrical nerve stimulation, or TENS)
• Injecting sterile water into the lower back, which can relieve the intense discomfort and pain in the lower back known as back labor

Lamaze International offers information on many aspects of natural childbirth in its Healthy Birth Practices website.

Cesarean delivery may be necessary in the following circumstances:^1,3

• Labor is not progressing. Contractions may not open the cervix enough for the baby to move into the vagina for delivery.
• The infant's health is in danger. The umbilical cord, which connects the fetus to the uterus, may become pinched, or the fetus may have an abnormal heart rate. In these cases, a cesarean delivery allows the baby to be delivered quickly to address and resolve the baby's health problems.
• The baby is in the wrong position. Most often when this occurs, the baby is breech, or in a breech presentation, meaning that the baby is coming out feet first instead of head first. The baby may also be in a transverse (sideways) or oblique (diagonal) position.
• The pregnant woman is delivering two or more fetuses (multiple pregnancy). A cesarean delivery may be needed if labor has started too early (preterm labor), if the fetuses are not in good positions within the uterus for natural delivery, or if there are other problems.
• The baby is too large. Larger infants are at risk for complications during delivery. These include shoulder dystocia (pronounced dis-TO-she-ah), when the infant's head is delivered through the vagina but the shoulders are stuck.⁴ Women with gestational diabetes, especially if their blood sugar levels are not well controlled, are at increased risk for having large babies.
• The placenta has problems. Sometimes the placenta is not formed or working correctly, is in the wrong place in the uterus, or is implanted too deeply or firmly in the uterine wall. These issues can cause problems, such as preventing needed oxygen and nutrients from reaching the fetus or causing vaginal bleeding.⁵
• The mother has an infection, such as HIV or herpes, that could be passed to the baby during vaginal birth. Cesarean delivery could help prevent transmission of the virus to the infant.
• The mother has a specific medical condition. A cesarean delivery enables the health care provider to better manage the mother's health issues.

Women who have a cesarean delivery may be given pain medication with an epidural block, a spinal block, or general anesthesia. An epidural block numbs the lower part of the body through an injection in the spine. A spinal block also numbs the lower part of the body, but through an injection directly into the spinal fluid. Women who receive general anesthesia, often used for emergency cesarean deliveries, will not be awake during the surgery.¹

Cesarean delivery is a type of surgery, so it has risks and possible complications for both mother and baby.

Possible risks from a cesarean delivery include:¹

• Infection
• Blood loss
• Blood clots in the legs, pelvic organs, or lungs
• Injury to surrounding structures, such as the bowel or bladder
• Reaction to medication or anesthesia used

It is important to note that these risks also apply, to some degree, to vaginal birth.

A woman who has a cesarean delivery may also have to stay in the hospital longer than a woman who has had a vaginal delivery.

The more cesarean deliveries a woman has, the greater her risk of certain medical problems and problems with future pregnancies, such as uterine rupture and problems with the placenta.⁶

Some women may want to have a cesarean birth even if vaginal delivery is an option. Women should discuss their options in detail with their health care provider before making a decision about a type of delivery. The decision should consider the impact of the delivery not only on the current pregnancy but also on future pregnancies. The safest method of delivery for both the mother and the fetus is an uncomplicated vaginal delivery.

Regardless of the type of delivery, unless there is a medical necessity, delivery should not occur before 39 weeks of pregnancy (called "full term"). Watch this video to learn why it is important for the mother's and infant's health to wait until at least 39 weeks to deliver unless there is a medical reason to do so earlier.

Division of Extramural Research (DER)

Several organizational units within the DER support research on labor and delivery:

The Pregnancy and Perinatology Branch (PPB) seeks to improve the health of mothers and children by supporting research in several areas related to pregnancy, including labor and delivery. PPB-supported studies examine the development of the placenta and how it relates to labor and delivery outcomes; racial and ethnic disparities in preterm birth rates; adverse effects of oxytocin receptor desensitization due to prolonged oxytocin infusion during labor induction; molecular mechanisms of uterine contractions during normal labor, preterm labor, and post-term pregnancies; neural regulation of pre-partum cervical ripening; comparative effectiveness of antibiotics for cesarean delivery; development of improved labor diagnostic devices; obstetrical determinants of neonatal survival; and labor induction versus expectant management in post-term pregnancy.

• PPB-supported finding: Even a partial steroid treatment can improve survival and longer-term health among extremely preterm infants, researchers in NICHD's Neonatal Research Network found. A 48-hour course of steroids helps the lungs and other organs develop, improving survival for infants born at 22 to 27 weeks of pregnancy. But what a provider should do when not enough time is available to complete treatment before delivery has not been clear. After examining about 6,000 cases, the researchers found that mothers who received some treatment were more likely than those who did not to give birth to infants who survived, and their infants had fewer birth complications and developmental disabilities 1.5 years and nearly 2 years after birth. (PMID: 27723868)
• PPB-supported finding: When cesarean delivery is unplanned, adding a second antibiotic to standard measures to prevent infection could reduce infection rates by half. About 12% of women who undergo unplanned surgery to deliver their baby develop an infection. After studying more than 2,000 deliveries, researchers funded by NICHD found that 6.1% of women given the standard antibiotic treatment, cephalosporin, plus a second antibiotic, azithromycin, later developed an infection, compared with 12% of women receiving only cephalosporin. (PMID: 28076707)

The Obstetric and Pediatric Pharmacology and Therapeutics Branch (OPPTB) supports obstetric clinical trials, including studies of algorithms for simulation and new methods for using medical record data, and other research that can improve understanding of how to appropriately use pharmaceuticals during pregnancy, including medications commonly used during labor and delivery.

The Maternal and Pediatric Infectious Disease Branch (MPIDB) supports and conducts a wide range of domestic and international research related to the epidemiology, diagnosis, clinical manifestations, pathogenesis, transmission, treatment, and prevention of emerging infectious diseases such as Zika virus, HIV infection. MPIDB also supports and conducts research on infectious and non-infectious complications associated with HIV in pregnant women, infants, and the family unit as a whole. For example, MPIDB-supported researchers are investigating how tenofovir vaginal gel, a medication given during pregnancy, works to treat HIV and to prevent transmission of the virus from mother to child.

The Population Dynamics Branch supports research on demography, reproductive health, and population health. Current studies are examining the effect of mode of first delivery on subsequent childbearing and the role of prenatal employment in health care choices and services during childbirth.

Division of Intramural Population Health Research (DIPHR)

DIPHR conducts research to identify critical data gaps and designs research initiatives to answer etiologic questions or to evaluate interventions aimed at modifying behavior related to public health.

The Consortium on Safe Labor (CSL), led by researchers within the DIPHR's Epidemiology Branch, is an observational study whose goals are to explore the underlying causes of the high cesarean delivery rate in the U.S. population, describe contemporary labor progression at the national level, determine when is the most appropriate time to perform a cesarean delivery in women with labor protraction and arrest, and examine air quality and its effect on reproductive health and birth outcomes. The CSL includes 12 clinical centers and 228,562 pregnancies from across the United States. CSL research findings include the following:

• Compared with women who have a typical first-time pregnancy, women who attempt labor after a previous cesarean delivery experience a slower progression of labor, especially during the stages when the cervix dilates from 4 to 7 or 8 centimeters. A better understanding of the typical progression of labor could help providers better manage labor and delivery in a variety of circumstances. (PMID: 25935774)
• Women spend more time in labor now than approximately 50 years ago. The implication of this finding is that preventing cesarean delivery in the first pregnancy will go a long way toward decreasing the national cesarean delivery rate. Because providers are using definitions of "abnormal labor" developed in a population of women who are different from the contemporary obstetrical population, the CSL findings suggest that routine interventions, such as the use of oxytocin and timing of cesarean delivery, as well as modern-day labor process management, warrant reconsideration. (PMID: 22542117)
• A prolonged second stage of labor was associated with highly successful vaginal delivery rates but also with small increases in maternal and serious neonatal morbidity, as well as perinatal mortality in deliveries without an epidural. Investigators assessed neonatal and maternal outcomes when the second stage—the time from when pushing begins until delivery of the baby—was prolonged, according to American College of Obstetricians and Gynecologists (ACOG) guidelines. The findings suggest that the benefits of vaginal delivery need to be weighed against the increased maternal and neonatal risks when second-stage labor lasts longer than described in the ACOG guidelines. (PMID: 24901265)
• Certain nonmedical factors are common in cesarean deliveries. Researchers using CSL data studied medical records from more than 145,000 deliveries involving a trial of labor. The baby was delivered by C-section in about 20,000 cases. The researchers analyzed the impact of factors such as when the delivery occurred, certain provider characteristics, the type of insurance used, patient characteristics, and policies at the institution. They learned that delivery in the evening, a male provider, a nonwhite mother, and use of Medicaid were associated with cesarean delivery. Understanding how these factors affect decision making about delivery could help with the design of ways to reduce high cesarean rates. (PMID: 23670226)

Other areas of ongoing research include determining the optimal time for the second stage of labor and exploring how sociodemographic changes in the current obstetrical population have affected pregnancy complications; maternal and neonatal morbidity; and implications for clinical management, including delivery timing and route. Researchers are also exploring how chronic diseases, such as hypertension, diabetes, and asthma, affect these outcomes. Further work from the CSL study will help shape the future clinical care of pregnant women.

Division of Intramural Research (DIR)

The Program in Perinatal Research and Obstetrics (PPRO) within the DIR conducts clinical and laboratory research on maternal and fetal diseases responsible for excessive infant mortality in the United States.

NICHD's research related to Preterm Labor and Birth is covered in the Preterm Labor and Birth topic.

• Global Network for Women's and Children's Health Research 
  This PPB-supported network is a partnership committed to improving maternal and infant health outcomes and building health research capacity in resource-poor settings by testing cost-effective, sustainable interventions. U.S. researchers are paired with investigators in India, Pakistan, Guatemala, Zambia, Kenya, and the Democratic Republic of Congo. The Network's efforts include tracking pregnancy services and outcomes through a registry that enrolls 60,000 women each year, promoting the use of corticosteroids to reduce newborn death, training birth attendants in techniques to increase infant survival, investigating the effect of nutritional interventions on infant health, and assessing the impact of ultrasound screening on maternal and infant health.
• International Maternal, Pediatric, Adolescent AIDS Clinical Trials (IMPAACT) Network 
  The MPIDB-funded IMPAACT Network is a cooperative group of institutions, investigators, and other collaborators focused on evaluating potential therapies for HIV infection and its related symptoms in infants and pregnant women, including clinical trials of HIV/AIDS interventions for and prevention of mother-to-child transmission.
• Maternal-Fetal Medicine Units (MFMU) Network 
  This PPB-funded network was established in 1986 to respond to the need for well-designed clinical trials in maternal-fetal medicine and obstetrics, particularly trials that focus on preterm birth. The MFMU Network is studying the effect of inducing labor on the risk of serious illness or infant death, progesterone for preventing preterm twin births, transmission of the hepatitis C virus from mothers to infants, and prevention of congenital cytomegalovirus infection.
• National Child and Maternal Health Education Program (NCMHEP) 
  The NCMHEP Is It Worth It? Initiative describes the benefits to mother and baby of waiting until at least 39 weeks of pregnancy to deliver, unless it is medically necessary to deliver earlier. NCMHEP's Know Your Terms Initiative explains recent changes in the definition of "full term."
• NICHD Domestic and International Pediatric and Maternal HIV Clinical Studies Network 
  This MPIDB-supported network conducts trials related to preventing and treating HIV infection and its complications in newborns and pregnant women.
• NIH Consensus Development Conference Archive 
  For these conferences, independent panels of health professionals and public representatives prepared consensus and state-of-the-science statements based on the results of a systematic literature review.
  • Vaginal Birth After Cesarean: New Insights (2010)
• Maternal and Pediatric Precision in Therapeutics (MPRINT) Hub 
  The OPPTB-supported OPRU Network provides the expert infrastructure needed to test therapeutic drugs during pregnancy. OPRU Network studies are investigating medications to alter uterine activity, such as those used to delay or prevent preterm birth and to treat gestational and type 2 diabetes, severe nausea, and other side effects of pregnancy and cancer as well as other series conditions in pregnant women.

Research activities and scientific advances in preterm labor and delivery are listed in the Preterm Labor and Birth topic.