Labor induction | |
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ICD-9-CM | 73.0-73.1 |
Labor induction is the process or treatment that stimulates childbirth and delivery. Inducing (starting) labor can be accomplished with pharmaceutical or non-pharmaceutical methods. In Western countries, it is estimated that one-quarter of pregnant women have their labor medically induced with drug treatment. [1] Inductions are most often performed either with prostaglandin drug treatment alone, or with a combination of prostaglandin and intravenous oxytocin treatment. [1]
Commonly accepted medical reasons for induction include:
Induction of labor in those who are either at or after term improves outcomes for newborns and decreases the number of C-sections performed. [3]
Methods of inducing labor include both pharmacological medication and mechanical or physical approaches.[ citation needed ]
Mechanical and physical approaches can include artificial rupture of membranes or membrane sweeping. Membrane sweeping may lead to more women spontaneously going into labor (and fewer women having labor induction) but it may make little difference to the risk of maternal or neonatal death, or to the number of women having c-sections or spontaneous vaginal births. There are also risks associated with membrane sweeping. The risks include irregular contractions, bleeding, and in 1 out of every 10 women an amniotic sac rupture, which can lead to a formal induction within 24 hours of the rupture if labor hasn't been induced. [4]
The use of intrauterine catheters are also indicated. These work by compressing the cervix mechanically to generate release on prostaglandins in local tissues. There is no direct effect on the uterus. Results from a 2021 systematic review found no differences in cesarean delivery nor neonatal outcomes in women with low-risk pregnancies between inpatient nor outpatient cervical ripening. [5]
The American Congress of Obstetricians and Gynecologists has recommended against elective induction before 39 weeks if there is no medical indication and the cervix is unfavorable. [13] One recent study indicates that labor induction at term (41 weeks) or post-term reduces the rate of caesarean section by 12%, and also reduces fetal death. [14] Some observational/retrospective studies have shown that non-indicated, elective inductions before the 41st week of gestation are associated with an increased risk of requiring a caesarean section. [13] Randomized clinical trials have not addressed this question. However, researchers have found that multiparous women who undergo labor induction without medical indicators are not predisposed to caesarean sections. [15] Doctors and pregnant women should have a discussion of risks and benefits when considering an induction of labor in the absence of an accepted medical indication. [13] There is insufficient evidence to determine if inducing a woman's labor at home is a safe and effective approach for both the women and the baby. [16]
Studies have shown a slight increase in risk of infant mortality for births in the 41st and particularly 42nd week of gestation, as well as a higher risk of injury to the mother and child. [17] Due to the increasing risks of advanced gestation, induction appears to reduce the risk for caesarean delivery after 41 weeks' gestation and possibly earlier. [14] [18] Inducing labour after 41 weeks of completed gestion is likely to reduce the risk of perinatal death and stillbirth compared with waiting for labour to start spontaneously. [19]
Although there has been a recorded increase in the risk of perinatal death and stillbirth after 41 weeks of gestation, this risk is small. In fact, a study conducted in 2012 examined stillbirth rates in the state of California, and excluded babies with genetic or congenital problems. The study determined that the risk of stillbirth per 1000 births after 40, 41 and 42 weeks of gestation were 0.42, 0.61 and 1.08, respectively. [20] Thus, it is important to acknowledge the probabilistic evidence when discussing formal medical inductions, because it highlights the how small the likelihood of having a stillbirth post-term is.
Inducing labor before 39 weeks in the absence of a medical indication (such as hypertension, IUGR, or pre-eclampsia) increases the risk of complications of prematurity including difficulties with respiration, infection, feeding, jaundice, neonatal intensive care unit admissions, and perinatal death. [21]
Inducing labour after 34 weeks and before 37 weeks in women with hypertensive disorders (pre-eclampsia, eclampsia, pregnancy-induced hypertension) may lead to better outcomes for the woman but does not improve or worsen outcomes for the baby. [22] More research is needed to produce more certain results. [22] If waters break (membranes rupture) between 24 and 37 weeks' gestation, waiting for the labour to start naturally with careful monitoring of the woman and baby is more likely to lead to healthier outcomes. [23] For women over 37 weeks pregnant whose babies are suspected of not coping well in the womb, it is not yet clear from research whether it is best to have an induction or caesarean immediately, or to wait until labour happens by itself. [24] Similarly, there is not yet enough research to show whether it is best to deliver babies prematurely if they are not coping in the womb or whether to wait so that they are less premature when they are born. [25]
Clinicians assess the odds of having a vaginal delivery after labor induction by a "Bishop score". However, recent research has questioned the relationship between the Bishop score and a successful induction, finding that a poor Bishop score actually may improve the chance for a vaginal delivery after induction. [14] A Bishop Score is done to assess the progression of the cervix prior to an induction. In order to do this, the cervix must be checked to see how much it has effaced, thinned out, and how far dilated it is. The score goes by a points system depending on five factors. Each factor is scored on a scale of either 0–2 or 0–3, any total score less than 5 holds a higher risk of delivering by caesarean section. [26]
Sometimes when a woman's waters break after 37 weeks she is induced instead of waiting for labour to start naturally. [27] This may decrease the risks of infection for the woman and baby but more research is needed to find out whether inducing is good for women and babies longer term. [27]
Women who have had a caesarean section for a previous pregnancy are at risk of having a uterine rupture, when their caesarean scar re-opens. [28] Uterine rupture is very serious for the woman and the baby, and induction of labour increases this risk further. [28] There is not yet enough research to determine which method of induction is safest for a woman who has had a caesarean section before. [28] There is also no research to say whether it is better for these women and their babies to have an elective caesarean section instead of being induced. [29]
Membrane sweeping, a common method of labor induction, can cause bleeding and irregular contractions and is often done without informed consent by the pregnant person. [30]
The medical rationale for performing an induction is decreasing the risk of stillbirth. However, as mentioned in the above section, the probability of having a stillbirth post-term is very small, meaning that for the vast majority of post-term pregnancies, inductions are unnecessary. Approximately 500 inductions are performed in order to avoid 1 stillbirth. [31] Many of these unnecessary inductions could potentially provoke other risks, forcing medical practitioners to perform other interventions such as caesarean sections. These additional interventions could cause labor to be more risky for the pregnant person.
Another criticism of inductions is that the pregnant person's bodily autonomy is overlooked. Many pregnant people might not want to be induced, and rather share in the decision-making process with their medical practitioner. [32]
Induced labor may be more painful for the woman as one of the side effects of intravenous oxytocin is increased contraction pains, mainly due to the rigid onset. [33] This may lead to the increased use of analgesics and other pain-relieving pharmaceuticals. [34] These interventions may also lead to an increased likelihood of caesarean section delivery for the baby. [35] However, studies into this matter show differing results. One study indicated that while overall caesarean section rates from 1990 to 1997 remained at or below 20 per cent, elective induction was associated with a doubling of the rate of Caesarean section. [36] Another study showed that elective induction in women who were not post-term increased a woman's chance of a C-section by two to three times. [37] A more recent study indicated that induction may increase the risk of caesarean section if performed before the 40th week of gestation, but it has no effect or actually lowers the risk if performed after the 40th week. [38] [39]
A 2014 systematic review and meta analysis on the subject of induction and its effect on cesarean section indicate that after 41 weeks of gestation there is a reduction of cesarean deliveries when the labour is induced. [14] [40]
The Institute for Safe Medication Practices labeled pitocin a "high-alert medication" because of the high likelihood of "significant patient harm when it is used in error." [41]
Caesarean section, also known as C-section or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen. It is often performed because vaginal delivery would put the mother or child at risk. Reasons for the operation include obstructed labor, twin pregnancy, high blood pressure in the mother, breech birth, shoulder presentation, and problems with the placenta or umbilical cord. A caesarean delivery may be performed based upon the shape of the mother's pelvis or history of a previous C-section. A trial of vaginal birth after C-section may be possible. The World Health Organization recommends that caesarean section be performed only when medically necessary.
Childbirth, also known as labour, parturition and delivery, is the completion of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million human births globally. In the developed countries, most deliveries occur in hospitals, while in the developing countries most are home births.
Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is between 28 and 32 weeks, early preterm birth occurs between 32 and 34 weeks, late preterm birth is between 34 and 36 weeks' gestation. These babies are also known as premature babies or colloquially preemies or premmies. Symptoms of preterm labor include uterine contractions which occur more often than every ten minutes and/or the leaking of fluid from the vagina before 37 weeks. Premature infants are at greater risk for cerebral palsy, delays in development, hearing problems and problems with their vision. The earlier a baby is born, the greater these risks will be.
A breech birth is when a baby is born bottom first instead of head first, as is normal. Around 3–5% of pregnant women at term have a breech baby. Due to their higher than average rate of possible complications for the baby, breech births are generally considered higher risk. Breech births also occur in many other mammals such as dogs and horses, see veterinary obstetrics.
External cephalic version (ECV) is a process by which a breech baby can sometimes be turned from buttocks or foot first to head first. It is a manual procedure that is recommended by national guidelines for breech presentation of a pregnancy with a single baby, in order to enable vaginal delivery. It is usually performed late in pregnancy, that is, after 36 gestational weeks, preferably 37 weeks, and can even be performed in the early stages of childbirth.
A hysterotomy is an incision made in the uterus. This surgical incision is used in several medical procedures, including during termination of pregnancy in the second trimester and delivering the fetus during caesarean section. It is also used to gain access and perform surgery on a fetus during pregnancy to correct birth defects, and it is an option to achieve resuscitation if cardiac arrest occurs during pregnancy and it is necessary to remove the fetus from the uterus.
Cervical dilation is the opening of the cervix, the entrance to the uterus, during childbirth, miscarriage, induced abortion, or gynecological surgery. Cervical dilation may occur naturally, or may be induced surgically or medically.
Prelabor rupture of membranes (PROM), previously known as premature rupture of membranes, is breakage of the amniotic sac before the onset of labour. Women usually experience a painless gush or a steady leakage of fluid from the vagina. Complications in the baby may include premature birth, cord compression, and infection. Complications in the mother may include placental abruption and postpartum endometritis.
Cervical effacement or cervical ripening refers to the thinning and shortening of the cervix. This process occurs during labor to prepare the cervix for dilation to allow the fetus to pass through the vagina. While this a normal, physiological process that occurs at the later end of pregnancy, it can also be induced through medications and procedures.
Cervical cerclage, also known as a cervical stitch, is a treatment for cervical weakness, when the cervix starts to shorten and open too early during a pregnancy causing either a late miscarriage or preterm birth. In women with a prior spontaneous preterm birth and who are pregnant with one baby, and have shortening of the cervical length less than 25 mm, a cerclage prevents a preterm birth and reduces death and illness in the baby.
Cervical weakness, also called cervical incompetence or cervical insufficiency, is a medical condition of pregnancy in which the cervix begins to dilate (widen) and efface (thin) before the pregnancy has reached term. Definitions of cervical weakness vary, but one that is frequently used is the inability of the uterine cervix to retain a pregnancy in the absence of the signs and symptoms of clinical contractions, or labor, or both in the second trimester. Cervical weakness may cause miscarriage or preterm birth during the second and third trimesters. It has been estimated that cervical insufficiency complicates about 1% of pregnancies, and that it is a cause in about 8% of women with second trimester recurrent miscarriages.
Postterm pregnancy is when a woman has not yet delivered her baby after 42 weeks of gestation, two weeks beyond the typical 40-week duration of pregnancy. Postmature births carry risks for both the mother and the baby, including fetal malnutrition, meconium aspiration syndrome, and stillbirths. After the 42nd week of gestation, the placenta, which supplies the baby with nutrients and oxygen from the mother, starts aging and will eventually fail. Postterm pregnancy is a reason to induce labor.
Uterine atony is the failure of the uterus to contract adequately following delivery. Contraction of the uterine muscles during labor compresses the blood vessels and slows flow, which helps prevent hemorrhage and facilitates coagulation. Therefore, a lack of uterine muscle contraction can lead to an acute hemorrhage, as the vasculature is not being sufficiently compressed. Uterine atony is the most common cause of postpartum hemorrhage, which is an emergency and potential cause of fatality. Across the globe, postpartum hemorrhage is among the top five causes of maternal death. Recognition of the warning signs of uterine atony in the setting of extensive postpartum bleeding should initiate interventions aimed at regaining stable uterine contraction.
Postpartum bleeding or postpartum hemorrhage (PPH) is often defined as the loss of more than 500 ml or 1,000 ml of blood following childbirth. Some have added the requirement that there also be signs or symptoms of low blood volume for the condition to exist. Signs and symptoms may initially include: an increased heart rate, feeling faint upon standing, and an increased breathing rate. As more blood is lost, the patient may feel cold, blood pressure may drop, and they may become restless or unconscious. In severe cases circulatory collapse, disseminated intravascular coagulation and death can occur. The condition can occur up to twelve weeks following delivery in the secondary form. The most common cause is poor contraction of the uterus following childbirth. Not all of the placenta being delivered, a tear of the uterus, or poor blood clotting are other possible causes. It occurs more commonly in those who already have a low amount of red blood, are Asian, have a larger fetus or more than one fetus, are obese or are older than 40 years of age. It also occurs more commonly following caesarean sections, those in whom medications are used to start labor, those requiring the use of a vacuum or forceps, and those who have an episiotomy.
Vasa praevia is a condition in which fetal blood vessels cross or run near the internal opening of the uterus. These vessels are at risk of rupture when the supporting membranes rupture, as they are unsupported by the umbilical cord or placental tissue.
A vaginal delivery is the birth of offspring in mammals through the vagina. It is the most common method of childbirth worldwide. It is considered the preferred method of delivery, as it is correlated with lower morbidity and mortality than caesarean sections (C-sections), though it is not clear whether this is causal.
A uterotonic, also known as an oxytocic or ecbolic, is a type of medication used to induce contraction or greater tonicity of the uterus. Uterotonics are used both to induce labor and to reduce postpartum hemorrhage.
Amnioinfusion is a method in which isotonic fluid is instilled into the uterine cavity.
Artificial rupture of membranes (AROM), also known as an amniotomy, is performed by a midwife or obstetrician and was once thought to be an effective means to induce or accelerate labor. The membranes can be ruptured using a specialized tool, such as an amnihook or amnicot, or they may be ruptured by the proceduralist's finger. The different techniques for artificial rupture of membranes have not been extensively compared in the literature. In one study comparing amnihook versus amnicot for artificial rupture of membranes, use of an amnicot was associated with fewer neonatal scalp lacerations.
Prolonged labor is the inability of a woman to proceed with childbirth upon going into labor. Prolonged labor typically lasts over 20 hours for first time mothers, and over 14 hours for women that have already had children. Failure to progress can take place during two different phases; the latent phase and active phase of labor. The latent phase of labor can be emotionally tiring and cause fatigue, but it typically does not result in further problems. The active phase of labor, on the other hand, if prolonged, can result in long term complications.