Labor induction is the process or treatment that stimulates
childbirth
Childbirth, also known as labour and delivery, is the ending 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 births glob ...
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.
Inductions are most often performed either with
prostaglandin drug treatment alone, or with a combination of prostaglandin and intravenous
oxytocin treatment.
Medical uses
Commonly accepted medical reasons for induction include:
*
Postterm pregnancy
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, ...
, i.e. if the pregnancy has gone past the end of the 42nd week.
*
Intrauterine fetal growth restriction (IUGR).
* There are health risks to the woman in continuing the pregnancy (e.g. she has
pre-eclampsia).
*
Premature rupture of the membranes (PROM); this is when the membranes have ruptured, but labor does not start within a specific amount of time.
* Premature termination of the pregnancy (abortion).
* Fetal death in utero and previous history of stillbirth.
*
Twin
Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...
pregnancy continuing beyond 38 weeks.
* Previous health conditions that puts risk on the woman and/or her child such as
diabetes
Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...
,
high blood pressure
* High BMI
Induction of labor in those who are either at or after term improves outcomes for newborns and decreases the number of
C-sections performed.
Methods of induction
Methods of inducing labor include both pharmacological medication and mechanical or physical approaches.
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.
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
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
outcomes in women with low-risk pregnancies between inpatient nor outpatient cervical ripening.
Medication
*
Intravaginal, endocervical or
extra-amniotic administration of
prostaglandin, such as
dinoprostone
Prostaglandin E2 (PGE2), also known as dinoprostone, is a naturally occurring prostaglandin with oxytocic properties that is used as a medication. Dinoprostone is used in labor induction, bleeding after delivery, termination of pregnancy, and ...
or
misoprostol
Misoprostol is a synthetic prostaglandin medication used to prevent and treat stomach and duodenal ulcers, induce labor, cause an abortion, and treat postpartum bleeding due to poor contraction of the uterus. Misoprostol is taken by mouth w ...
.
Prostaglandin E2 is the most studied compound and with most evidence behind it. A range of different dosage forms are available with a variety of routes possible. The use of misoprostol has been extensively studied but normally in small, poorly defined studies. Only a very few countries have approved
misoprostol
Misoprostol is a synthetic prostaglandin medication used to prevent and treat stomach and duodenal ulcers, induce labor, cause an abortion, and treat postpartum bleeding due to poor contraction of the uterus. Misoprostol is taken by mouth w ...
for use in induction of labor.
*
Intravenous (IV) administration of synthetic
oxytocin preparations is used to artificially induce labor if it is deemed medically necessary.
A high dose of oxytocin does not seem to have greater benefits than a standard dose. There are risks associated with IV oxytocin induced labor. Risks include the women having induced contractions that are too vigorous, too close together (frequent), or that last too long, which may lead to added stress on the baby (changes in baby's heart rate) and may require the mother to have an emergency
caesarean section.
There is no high quality evidence to indicate if IV oxytocin should be stopped once a woman reaches active labor in order to reduce the incidence of women requiring caesarean sections.
* Use of
mifepristone
Mifepristone, also known as RU-486, is a medication typically used in combination with misoprostol to bring about a medical abortion during pregnancy and manage early miscarriage. This combination is 97% effective during the first 63 days of ...
has been described but is rarely used in practice.
*
*
Relaxin
Relaxin is a protein hormone of about 6000 Da first described in 1926 by Frederick Hisaw.
The relaxin family peptide hormones belong to the insulin superfamily and consists of seven peptides of high structural but low sequence similarity; rela ...
has been investigated,
but is not currently commonly used.
* mnemonic; ARNOP: Antiprogesterone, relaxin, nitric oxide donors, oxytocin, prostaglandins
Non-pharmaceutical
* Membrane sweep, also known as membrane stripping, Hamilton maneuver, or "stretch and sweep". The procedure is carried out by a midwife or doctor as part of an internal vaginal examination. The midwife or doctor puts a couple of lubricated, gloved fingers into the women's vagina and inserts their index finger into the opening of the cervix or neck of the womb. They then use a circular movement to try to separate the membranes of the amniotic sac, containing the baby, from the cervix. This action, which releases hormones called prostaglandins, may prepare the cervix for birth and may initiate labour.
*
Artificial rupture of the membranes (AROM or ARM) ("breaking the waters")
* Extra-amniotic saline infusion (EASI),
in which a
Foley catheter
In urology, a Foley catheter (named for Frederic Foley, who produced the original design in 1929) is a flexible tube that a clinician passes through the urethra and into the bladder to drain urine. It is the most common type of indwelling urinar ...
is inserted into the
cervix and the distal portion expanded to dilate it and to release prostaglandins.
* Cook Medical Double Balloon known as the Cervical Ripening Balloon with Stylet for assisted placement is FDA approved. The Double balloon provides one balloon to be inflated with saline on one side of the Uterine side of the cervix and the second balloon to be inflated with saline on the vaginal side of the cervix.
Pregnancy Acupuncturemay also help to kick start labour and avoid medical induction
Acupuncture for labour induction is a specialised form of acupuncture which focus on promoting blood flow to the uterus, stimulating the production of Oxytocin, which causes uterine contractions during labour. For the best results, it is suggested starting receiving this type of treatment from week 38 of pregnancy on a weekly basis.
When to induce
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.
[, which cites
*
* ] 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.
[Ekaterina Mishanina et al., "Use of labour induction and risk of cesarean delivery: a systematic review and meta-analysis", April 2014, Canadian Medical Association Journal]
/ref>
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. 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. 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. There is insufficient evidence to determine if inducing a women's labor at home is a safe and effective approach for both the women and the baby.
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. Due to the increasing risks of advanced gestation, induction appears to reduce the risk for caesarean delivery after 41 weeks' gestation and possibly earlier. Inducing labour after 41 weeks of completed gestion is likely to reduce the risk of perinatal death
Perinatal mortality (PNM) refers to the death of a fetus or neonate and is the basis to calculate the perinatal mortality rate. Variations in the precise definition of the perinatal mortality exist, specifically concerning the issue of inclusion o ...
and stillbirth compared with waiting for labour to start spontaneously.
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.
Inducing labour after 34 weeks and before 37 weeks in women with hypertensive disorders ( pre-eclampsia, eclampsia
Eclampsia is the onset of seizures (convulsions) in a woman with pre-eclampsia. Pre-eclampsia is one of the hypertensive disorders of pregnancy that presents with three main features: new onset of high blood pressure, large amounts of protein in ...
, pregnancy-induced hypertension) may lead to better outcomes for the woman but does not improve or worsen outcomes for the baby. More research is needed to produce more certain results. 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. 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. 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.
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. 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.
Sometimes when a woman's waters break after 37 weeks she is induced instead of waiting for labour to start naturally. 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.
Women who have had a caesarean section for a previous pregnancy are at risk of having a uterine rupture
Uterine rupture is when the muscular wall of the uterus tears during pregnancy or childbirth. Symptoms, while classically including increased pain, vaginal bleeding, or a change in contractions, are not always present. Disability or death of the ...
, when their caesarean scar re-opens. Uterine rupture is very serious for the woman and the baby, and induction of labour increases this risk further. There is not yet enough research to determine which method of induction is safest for a woman who has had a caesarean section before. 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.
Criticisms of induction
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. This may lead to the increased use of analgesics and other pain-relieving pharmaceuticals. These interventions may also lead to an increased likelihood of caesarean section delivery for the baby. 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. 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. 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.
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.
The Institute for Safe Medication Practices labeled pitocin
Synthetic oxytocin, sold under the brand name Pitocin among others, is a medication made from the peptide '' oxytocin''. As a medication, it is used to cause contraction of the uterus to start labor, increase the speed of labor, and to stop ...
a "high-alert medication" because of the high likelihood of "significant patient harm when it is used in error."[The Institute for Safe Medication Practice]
''Results Of ISMP Survey On High-Alert Medications: Differences Between Nursing, Pharmacy, And Risk/Quality/Safety Perspectives''
ISMP.org. Retrieved 2017-01-09.
See also
* Tocolytic
Tocolytics (also called anti-contraction medications or labor suppressants) are medications used to suppress premature labor (from Greek τόκος ''tókos'', "childbirth", and λύσις ''lúsis'', "loosening"). Preterm birth accounts for 70% ...
, labor suppressant
References
External links
*
Inducing Labor – WebMD.com
Induction of labour
Clinical guideline, UK National Institute for Health and Clinical Excellence, June 2001.
* Josie L. Tenore
. American Family Physician, 15 May 2003.
* "Catecholamines – blood ." National Library of Medicine . N.p., n.d. Web. 28 Mar. 2011. .
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Childbirth
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