Uterotonic

Last updated September 08, 2023

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.^[1]

Labor induction in the third trimester of pregnancy may be required due to medical necessity, or may be desired for social reasons. Generally, labor induction is indicated when the risk of carrying the pregnancy outweighs the risk of delivering. These reason include, but are not limited to, pregnancies that are prolonged, prelabor rupture of the fetal membranes, and concerns about the health and safety of the mother and/or child. There are multiple techniques available to stimulate uterine contractions including mechanical, pharmacological, and alternative medicine methods to initiate contractions prior to spontaneous onset of labor.^[2]

Postpartum hemorrhage, also known as PPH, is defined as a loss of 500 mL or greater of blood within 24 hours after giving birth. It is one of the leading causes of maternal mortality in women and adolescent girls worldwide, with mothers from low-resource countries being at a larger risk when compared to mothers of higher-resource countries. Occurring in 5% of all women giving birth, these situations are considered emergencies and require a quick, adequate response and the proper resources to prevent the death of the mother.^[3]

Labor and delivery is a sequential process that results in the birth of a fetus and placenta. It is dependent on maternal and fetal chemical signals to stimulate muscles in the uterus to contract and relax. Of such signals include prostaglandins ^[4] and oxytocin.^[5] Uterotonics can be utilized in these chemical pathways in order to medically stimulate contractions in labor induction or to treat postpartum hemorrhage.

Types

Table 1: Types of Uterotonic drugs with pertinent drug information adapted from Obstetric Anesthesiology.^[6]
Utertonic	Administration	Onset	Duration of Action	Common Side Effects	Contraindications
Oxytocin	IV Bolus IV continuous infusion Intramuscularly (IM)	IV: < 1 min IM: 3-5 min	IV: 20 min IM: 30-90 min	IV: Hypotension, tachycardia, arrhythmia IM: Nausea and Vomiting	IV: Hypotension IM: Hemodynamically unstable
Carbetocin	IV bolus IM	IV & IM: 2 min	IV: 60 min IM: 120 min	IV: Hypotension, tachycardia, arrhythmia IM: Nausea and Vomiting	IV: Hypotension IM: Hemodynamically unstable
Misoprostol	Oral (PO) Sublingual (SL) Vaginal (PV) Rectal (PR)	PO: 8 min SL:11 min PV: 20 min PR: 100 min	PO: 120 min SL: 180 min PV: 240 min PR: 240 min	Fever Diarrhea Nausea Vomiting
Carboprost	IM Intramyometrial (IMM)	IM: 3-5 min IMM: No data	IM: 60-120 min IMM: No data	IM: Bronchospasm IMM: Nausea, vomiting, shivering	IM: Asthma IMM: Caution in liver, kidney or heart disease.
Ergometrine	IV IM	IV: < 1 min IM: 2-3 min	IV: 45 min IM: 3 hours	IV: Hypertension IM: Nausea and Vomiting	IV: Hypertension IM: Myocardial Ischemia
Methylergonovine	IV IM	IV: < 1 min IM: 2-3 min	IV: 45 min IM: 3 hours	IV: Hypertension IM: Nausea and Vomiting	IV: Hypertension IM: Myocardial Ischemia

Oxytocin

Oxytocin is a peptide hormone produced in the hypothalamus that plays an important role in many physiological functions. These functions include, enhancing mood and social relationships, promotion of maternal behaviors and stimulations of uterine contractions, among others roles. Uterine muscle contractions are induced via a G-protein pathway stemming from the oxytocin receptor (OXTR), the binding and activation site of oxytocin.^[7] When oxytocin binds to its associated receptors in the uterus, a cascade is initiated that results in an increase in calcium and subsequently an increase in muscle contractions. The release of oxytocin helps to facilitate stronger contractions during labor to aid in delivery of the fetus. Additionally, during pregnancy, the uterine muscles have an increased concentration of oxytocin receptors, leading to an increased response to oxytocin as well.^[8]

Role in labor induction

Oxytocin is the most commonly used agent for labor induction. It is given intravenously since it is easily degraded by the body if given orally. While giving oxytocin, it is important to monitor the mother and the fetus, specifically the mother's uterine activity and the fetal heart rate. The more common side effects of oxytocin include tachysystole, hyponatremia, and hypotension. Tachysystole is an increased rate of uterine contractions. If this occurs, it can be managed by lowering the dosage of oxytocin. Hyponatremia is a decreased concentration of sodium in the body as a result of increased fluids. This occurs due to oxytocin's similar structure to vasopressin (antidiuretic hormone), which acts to retain water in the body. Hypotension, or low blood pressure, is also a common side effect due to oxytocin's ability to relax smooth muscle of vessels. In comparison to women in spontaneous labor, women in induced labor on oxytocin experience a longer latent phase, however the duration of labor after reaching active labor (when the cervix has reached 6 cm), the duration of labor is considered equal.^[9]

Role in postpartum hemorrhage

The most common cause of postpartum hemorrhage is a loss of muscle tone in the uterus. Normally, the uterus will contract to constrict blood vessels and decrease the flow of blood to prevent bleeding out. However, if there is a loss of muscle tone, see uterine atony, there is an increased risk of bleeding. Oxytocin is the first-line pharmacological step to help prevent PPH and treat PPH.^[8]

Analogs

Oxytocin plays an integral role in regulation of many of the body's biological processes- especially labor regulation. Since its structure was revealed in 1953, it has been the subject of intensive research.^[10] Some of the analogs produced from extensive modification of its chemical structure residues have produced drugs and therapies that are utilized as uterotonics. Similar to oxytocin, analogues bind to oxytocin receptors found along the muscles of the uterus and act as an agonist. During pregnancy, the number of oxytocin receptors increase until reaching their peak near completion of the pregnancy. An important note is that not all analogs of oxytocin work as an receptor agonist or as a uterotonic. Some may oppose uterine contractility such as atosiban.^[11]

Carbetocin

Carbetocin: A long-acting synthetic analog with a half-life 4 to 10 times longer than natural oxytocin, it is used to control postpartum hemorrhaging or bleeding after giving birth. Heat-stable carbetocin does not require refrigeration unlike oxytocin; an notable advantage for use in low medical resource areas.^[12] It is approved for use in 23 various countries around the world (not approved in United States).^[11] In Canadian and German guidelines, carbetocin is recommended as a first-line therapy treatment for post-partum hemorrhaging with notable efficacy when used with cesarean section deliveries.^[10] Carbetocin has been shown to be more effective than oxytocin in preventing postpartum hemorrhaging as well. Common side effects of carbetocin include vomiting, fever, and hypertension- similar side effect profile to that of oxytocin.^[10] Both carbetocin and oxytocin are listed on the World Health Organization's Essential Medicines List.^[10]

Demoxytocin is another analog of oxytocin which is also used to induce labor.

Prostaglandins

Prostaglandins are derived from the cell membrane phospholipids through a series of enzymatic reactions. Phospholipase A2 cleaves arachidonic acid from membrane phospholipids and is eventually converted to prostaglandins by cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Due to this mechanism, prostaglandins have a presence in many areas of the body and allow for diverse physiological and pathological functions. Primarily known for its role in mediating inflammation: pain, swelling, redness, and warmth, prostaglandin synthesis is a target for many drugs. Inhibition of COX-1 and COX-2 by aspirin and non-steroidal anti-inflammatory drugs prevents the inflammatory response and can also prevent homeostatic functions of the stomach and GI system that may lead to ulcers and bleeding.^[13]

Prostaglandins (PG) have been attributed to partaking in the mechanisms of uterine activity during labor. The presence of prostaglandins and PG receptors increases throughout the pregnancy and increase expression of oxytocin receptors as well. Along with the increase in oxytocin receptors to facilitate labor, prostaglandins also increase the intracellular concentration of calcium.^[6] Two PG subtypes, E and F, play fundamental roles in labor, PG E receptors, activated by PGE1 and PGE2 are more uteroselective and will stimulate contraction or relaxation depending on the subtype. PG F receptors will stimulate myometrial contraction, although the stimulus from PG F receptors are inferior to oxytocin. For this reason, injectable PGs are not used as first line treatment. Adverse effects of injectable PGs include hypotension and pulmonary edema.^[14]

Misoprostol

Misoprostol: an analogue of PGE1, this injectable PG is a popular choice for PPH prophylaxis and treatment. Misoprostol is easily administered, considered safe, and is low cost. The routes of administration include sublingual, oral, vaginal, and rectal with greatest efficacy from sublingual and vaginal administration. Vaginally administered misoprostol had improved outcomes of inducing labor within twenty four hours compared to oxytocin, but was associated with uterine hyperstimulation.^[15] Misoprostol is an agonist of EP1 and EP3 receptors, and can cause a greater stimulation at lower concentrations. At higher concentrations, the medication can suppress contractions.^[14]

Carboprost

Carboprost: an analogue of PGF 2α, this prostaglandin contains oxytocic properties that permit a longer duration of action than the naturally occurring prostaglandins. The injectable prostaglandin is administered via intramuscularly or intramyometrial, and is used in clinical practice. The drug is contraindicated in those with reactive airway diseases. Side effects of this medication include hypertension, hypotension, pulmonary hypertension, vomiting and diarrhea.^[14]^[6]

Other prostaglandins

Alprostadil: commonly known as PGE1, is a naturally occurring prostaglandin and vasodilator. Alprostadil has not been added to the guidelines to treat PPH. The medication is not indicated for inducing labor, PPH, nor women, but for erectile dysfunction.^[14]
Dinoprostone: commonly known as PGE2, has the ability to stimulate both contractility and relaxation in the uterus during pregnancy. The area of action differs for each effect, contraction occurs in the upper uterine segment while relaxation occurs in the lower uterine segment.^[14] Not as efficacious for inducing labor when compared to other prostaglandins.^[16]
Dinoprost: also known as PGF 2α, is a naturally occurring prostaglandin which causes contraction via PG F receptors. Dinoprost was discontinued in 2015.^[14]

Ergot alkaloids

Ergot Alkaloids refer to a set of medications derived from the rye ergot fungus with mixed receptor activity that work to increase uterine muscle tone.^[8] Unlike oxytocinergic uterotonics, ergot alkaloids work primarily through agonistic activity of serotonin receptors along the smooth muscles of the uterine wall.

Ergometrine

Ergometrine, also known as ergonovine. Ergometrine is the first drug to be isolated from the rye ergot fungus. Ergometrine is often used alongside oxytocin to treat postpartum hemorrhaging and has been found to more effective than the standard of oxytocin treatment alone.^[10] Ergometrine has a relatively quick onset of action following intravenous administration (one minute) with the duration of action averaging 45 minutes (rhythmic contracts will persist for up to 3 hours following administration).^[8]

Methylergonovine

Methylergonovine, a synthetic analog of ergometrine that is primarily used to treat postpartum hemorrhaging due to uterine atony.^[10] Similar to ergometrine, methylergonovine works through agonism of the serotonin receptors found on the smooth muscles of the uterine wall. It has partial agonist activity on α-adrenergic receptors as well as weak antagonistic activity on dopamine receptors.^[8] Methylergonovine is intravenously administered with onset and duration of action similar to that of ergometrine. Its most common side effect is hypertension. Methylergonovine is recommended as a second-line therapy in treating postpartum hemorrhaging due to uterine atony according to both the American College of Obstetricians and Gynecologists (ACOG) and the Royal College of Obstetrics and Gynecology. In 2012, ACOG published a warning regarding use of methylergonovine's usage in people with hypertension where it was suspected to have caused myocardial infarction and ischemia in those individuals.^[8]

Related Research Articles

Prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals. They are derived enzymatically from the fatty acid arachidonic acid. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring. They are a subclass of eicosanoids and of the prostanoid class of fatty acid derivatives.

<span class="mw-page-title-main">Misoprostol</span> Medication to induce abortion and treat ulcers

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. It is taken by mouth when used to prevent gastric ulcers in people taking nonsteroidal anti-inflammatory drugs (NSAID). For abortions it is used by itself or in conjunction with mifepristone or methotrexate. By itself, effectiveness for abortion is between 66% and 90%. For labor induction or abortion, it is taken by mouth, dissolved in the mouth, or placed in the vagina. For postpartum bleeding it may also be used rectally.

Uterine contractions are muscle contractions of the uterine smooth muscle that occur during the menstrual cycle and labour. Uterine contractions occur throughout the menstrual cycle in the non-pregnant state and throughout gestation.

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. Inductions are most often performed either with prostaglandin drug treatment alone, or with a combination of prostaglandin and intravenous oxytocin treatment.

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.

Bloody show or show is the passage of a small amount of blood or blood-tinged mucus through the vagina near the end of pregnancy. It is caused by thinning and dilation of the cervix, leading to detachment of the cervical mucus plug that seals the cervix during pregnancy and tearing of small cervical blood vessels, and is one of the signs that labor may be imminent. The bloody show may be expelled from the vagina in pieces or altogether and often appears as a jelly-like piece of mucus stained with blood. Although the bloody show may be alarming at first, it is not a concern of patient health after 37 weeks gestation.

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 mother or baby may result.

<span class="mw-page-title-main">Ergometrine</span> Lysergamide

Ergometrine, also known as ergonovine and sold under the brand names Ergotrate, Ergostat, and Syntometrine among others, is a medication used to cause contractions of the uterus to treat heavy vaginal bleeding after childbirth. It can be used either by mouth, by injection into a muscle, or injection into a vein. It begins working within 15 minutes when taken by mouth and is faster in onset when used by injection. Effects last between 45 and 180 minutes.

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.

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 in newborn babies to keep the ductus arteriosus open. In babies it is used in those with congenital heart defects until surgery can be carried out. It is also used to manage gestational trophoblastic disease. It may be used within the vagina or by injection into a vein.

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. The condition can occur up to six weeks following delivery.

<span class="mw-page-title-main">Carbetocin</span> Pabal contains carbetocin used for preventing postpartum bleeding. Potent than oxytocin.

Carbetocin, sold under the brand names Pabal among others, is a medication used to prevent excessive bleeding after childbirth, particularly following Cesarean section. It appears to work as well as oxytocin. Due to it being less economical than other options, use is not recommended by NHS Scotland. It is given by injection into a vein or muscle.

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, with lower morbidity and mortality than Caesarean sections (C-sections).

<span class="mw-page-title-main">Prostaglandin F2alpha</span> Chemical compound

Prostaglandin F_2α, pharmaceutically termed carboprost is a naturally occurring prostaglandin used in medicine to induce labor and as an abortifacient. Prostaglandins are lipids throughout the entire body that have a hormone-like function. In pregnancy, PGF2 is medically used to sustain contracture and provoke myometrial ischemia to accelerate labor and prevent significant blood loss in labor. Additionally, PGF2 has been linked to being naturally involved in the process of labor. It has been seen that there are higher levels of PGF2 in maternal fluid during labor when compared to at term. This signifies that there is likely a biological use and significance to the production and secretion of PGF2 in labor. Prostaglandin is also used to treat uterine infections in domestic animals.

Oxytocin/ergometrine (trade name Syntometrine) is an obstetric combination drug. The components are synthetically produced oxytocin, a human hormone produced in the hypothalamus, and ergometrine, an alpha-adrenergic, dopaminergic and serotonin (5-HT₂) receptor agonist.

Uterine Tachysystole is a condition of excessively frequent uterine contractions during pregnancy. It is most often seen in induced or augmented labor, though it can also occur during spontaneous labor, and this may result in fetal hypoxia and acidosis. This may have serious effects on both the mother and the fetus including hemorrhaging and death. There are still major gaps in understanding treatment as well as clinical outcomes of this condition. Uterine tachysystole is defined as more than 5 contractions in 10 minutes, averaged over a 30-minute period.

Retained placenta is a condition in which all or part of the placenta or membranes remain in the uterus during the third stage of labour. Retained placenta can be broadly divided into:

Placental expulsion occurs when the placenta comes out of the birth canal after childbirth. The period from just after the baby is expelled until just after the placenta is expelled is called the third stage of labor.

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 bleeding following delivery. For this purpose, it is given by injection either into a muscle or into a vein.

References

↑ Mousa HA, Blum J, Abou El Senoun G, Shakur H, Alfirevic Z, et al. (Cochrane Pregnancy and Childbirth Group) (February 2014). "Treatment for primary postpartum haemorrhage". The Cochrane Database of Systematic Reviews. 2017 (2): CD003249. doi:10.1002/14651858.CD003249.pub3. PMC 6483801 . PMID 24523225.
↑ Mozurkewich EL, Chilimigras JL, Berman DR, Perni UC, Romero VC, King VJ, Keeton KL (October 2011). "Methods of induction of labour: a systematic review". BMC Pregnancy and Childbirth. 11: 84. doi: 10.1186/1471-2393-11-84 . PMC 3224350 . PMID 22032440.
↑ World Health Organization (7 November 2018). WHO recommendations. Uterotonics for the prevention of postpartum haemorrhage. Continuation of work: World Health Organization. Geneva. ISBN 9789241550420. OCLC 1143281597.{{cite book}}: CS1 maint: location missing publisher (link)
↑ Thomas J, Fairclough A, Kavanagh J, Kelly AJ (June 2014). "Vaginal prostaglandin (PGE2 and PGF2a) for induction of labour at term". The Cochrane Database of Systematic Reviews. 2014 (6): CD003101. doi:10.1002/14651858.CD003101.pub3. PMC 7138281 . PMID 24941907.
↑ Uvnäs-Moberg K, Ekström-Bergström A, Berg M, Buckley S, Pajalic Z, Hadjigeorgiou E, et al. (August 2019). "Maternal plasma levels of oxytocin during physiological childbirth - a systematic review with implications for uterine contractions and central actions of oxytocin". BMC Pregnancy and Childbirth. 19 (1): 285. doi: 10.1186/s12884-019-2365-9 . PMC 6688382 . PMID 31399062.
1 2 3 Obstetric anesthesiology : an illustrated case-based approach. Husain, Tauqeer, 1979-, Fernando, Roshan, Segal, Scott. Cambridge. 2019. ISBN 978-1-316-15547-9. OCLC 1096436796.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
↑ Jurek B, Neumann ID (July 2018). "The Oxytocin Receptor: From Intracellular Signaling to Behavior". Physiological Reviews. 98 (3): 1805–1908. doi: 10.1152/physrev.00031.2017 . PMID 29897293.
1 2 3 4 5 6 Vallera C, Choi LO, Cha CM, Hong RW (June 2017). "Uterotonic Medications: Oxytocin, Methylergonovine, Carboprost, Misoprostol". Anesthesiology Clinics. 35 (2): 207–219. doi:10.1016/j.anclin.2017.01.007. PMID 28526143.
↑ Budden A, Chen LJ, Henry A, et al. (Cochrane Pregnancy and Childbirth Group) (October 2014). "High-dose versus low-dose oxytocin infusion regimens for induction of labour at term". The Cochrane Database of Systematic Reviews. 2016 (10): CD009701. doi:10.1002/14651858.CD009701.pub2. PMC 8932234 . PMID 25300173.
1 2 3 4 5 6 Chao Y, McCormack S (2019). Carbetocin for the Prevention of Post-Partum Hemorrhage: A Review of Clinical Effectiveness, Cost-Effectiveness, and Guidelines. CADTH Rapid Response Reports. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health. PMID 31532600.
1 2 Rath W (November 2009). "Prevention of postpartum haemorrhage with the oxytocin analogue carbetocin". European Journal of Obstetrics, Gynecology, and Reproductive Biology. 147 (1): 15–20. doi:10.1016/j.ejogrb.2009.06.018. PMID 19616358.
↑ Theunissen FJ, Chinery L, Pujar YV (June 2018). "Current research on carbetocin and implications for prevention of postpartum haemorrhage". Reproductive Health. 15 (Suppl 1): 94. doi: 10.1186/s12978-018-0529-0 . PMC 6019985 . PMID 29945640.
↑ Crofford LJ (December 2001). "Prostaglandin biology". Gastroenterology Clinics of North America. 30 (4): 863–76. doi:10.1016/S0889-8553(05)70217-X. PMID 11764532.
1 2 3 4 5 6 Drew T, Balki M (November 2019). "What does basic science tell us about the use of uterotonics?". Best Practice & Research. Clinical Obstetrics & Gynaecology. Postpartum Haemorrhage. 61: 3–14. doi:10.1016/j.bpobgyn.2019.05.017. PMID 31326333. S2CID 198132393.
↑ Mozurkewich EL, Chilimigras JL, Berman DR, Perni UC, Romero VC, King VJ, Keeton KL (October 2011). "Methods of induction of labour: a systematic review". BMC Pregnancy and Childbirth. 11 (1): 84. doi: 10.1186/1471-2393-11-84 . PMC 3224350 . PMID 22032440.
↑ Wang L, Zheng J, Wang W, Fu J, Hou L (2016). "Efficacy and safety of misoprostol compared with the dinoprostone for labor induction at term: a meta-analysis". The Journal of Maternal-Fetal & Neonatal Medicine. 29 (8): 1297–307. doi:10.3109/14767058.2015.1046828. PMID 26067262. S2CID 29501108.

External links

"Oxytocics" . New International Encyclopedia . 1905.

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[1] Mousa HA, Blum J, Abou El Senoun G, Shakur H, Alfirevic Z, et al. (Cochrane Pregnancy and Childbirth Group) (February 2014). "Treatment for primary postpartum haemorrhage". The Cochrane Database of Systematic Reviews. 2017 (2): CD003249. doi:10.1002/14651858.CD003249.pub3. PMC 6483801 . PMID 24523225.

[2] Mozurkewich EL, Chilimigras JL, Berman DR, Perni UC, Romero VC, King VJ, Keeton KL (October 2011). "Methods of induction of labour: a systematic review". BMC Pregnancy and Childbirth. 11: 84. doi: 10.1186/1471-2393-11-84 . PMC 3224350 . PMID 22032440.

[3] World Health Organization (7 November 2018). WHO recommendations. Uterotonics for the prevention of postpartum haemorrhage. Continuation of work: World Health Organization. Geneva. ISBN 9789241550420. OCLC 1143281597.{{cite book}}: CS1 maint: location missing publisher (link)

[4] Thomas J, Fairclough A, Kavanagh J, Kelly AJ (June 2014). "Vaginal prostaglandin (PGE2 and PGF2a) for induction of labour at term". The Cochrane Database of Systematic Reviews. 2014 (6): CD003101. doi:10.1002/14651858.CD003101.pub3. PMC 7138281 . PMID 24941907.

[5] Uvnäs-Moberg K, Ekström-Bergström A, Berg M, Buckley S, Pajalic Z, Hadjigeorgiou E, et al. (August 2019). "Maternal plasma levels of oxytocin during physiological childbirth - a systematic review with implications for uterine contractions and central actions of oxytocin". BMC Pregnancy and Childbirth. 19 (1): 285. doi: 10.1186/s12884-019-2365-9 . PMC 6688382 . PMID 31399062.

[:2-6] 1 2 3 Obstetric anesthesiology : an illustrated case-based approach. Husain, Tauqeer, 1979-, Fernando, Roshan, Segal, Scott. Cambridge. 2019. ISBN 978-1-316-15547-9. OCLC 1096436796.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)

[7] Jurek B, Neumann ID (July 2018). "The Oxytocin Receptor: From Intracellular Signaling to Behavior". Physiological Reviews. 98 (3): 1805–1908. doi: 10.1152/physrev.00031.2017 . PMID 29897293.

[:1-8] 1 2 3 4 5 6 Vallera C, Choi LO, Cha CM, Hong RW (June 2017). "Uterotonic Medications: Oxytocin, Methylergonovine, Carboprost, Misoprostol". Anesthesiology Clinics. 35 (2): 207–219. doi:10.1016/j.anclin.2017.01.007. PMID 28526143.

[9] Budden A, Chen LJ, Henry A, et al. (Cochrane Pregnancy and Childbirth Group) (October 2014). "High-dose versus low-dose oxytocin infusion regimens for induction of labour at term". The Cochrane Database of Systematic Reviews. 2016 (10): CD009701. doi:10.1002/14651858.CD009701.pub2. PMC 8932234 . PMID 25300173.

[Chao_2019-10] 1 2 3 4 5 6 Chao Y, McCormack S (2019). Carbetocin for the Prevention of Post-Partum Hemorrhage: A Review of Clinical Effectiveness, Cost-Effectiveness, and Guidelines. CADTH Rapid Response Reports. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health. PMID 31532600.

[:3-11] 1 2 Rath W (November 2009). "Prevention of postpartum haemorrhage with the oxytocin analogue carbetocin". European Journal of Obstetrics, Gynecology, and Reproductive Biology. 147 (1): 15–20. doi:10.1016/j.ejogrb.2009.06.018. PMID 19616358.

[12] Theunissen FJ, Chinery L, Pujar YV (June 2018). "Current research on carbetocin and implications for prevention of postpartum haemorrhage". Reproductive Health. 15 (Suppl 1): 94. doi: 10.1186/s12978-018-0529-0 . PMC 6019985 . PMID 29945640.

[13] Crofford LJ (December 2001). "Prostaglandin biology". Gastroenterology Clinics of North America. 30 (4): 863–76. doi:10.1016/S0889-8553(05)70217-X. PMID 11764532.

[:0-14] 1 2 3 4 5 6 Drew T, Balki M (November 2019). "What does basic science tell us about the use of uterotonics?". Best Practice & Research. Clinical Obstetrics & Gynaecology. Postpartum Haemorrhage. 61: 3–14. doi:10.1016/j.bpobgyn.2019.05.017. PMID 31326333. S2CID 198132393.

[15] Mozurkewich EL, Chilimigras JL, Berman DR, Perni UC, Romero VC, King VJ, Keeton KL (October 2011). "Methods of induction of labour: a systematic review". BMC Pregnancy and Childbirth. 11 (1): 84. doi: 10.1186/1471-2393-11-84 . PMC 3224350 . PMID 22032440.

[16] Wang L, Zheng J, Wang W, Fu J, Hou L (2016). "Efficacy and safety of misoprostol compared with the dinoprostone for labor induction at term: a meta-analysis". The Journal of Maternal-Fetal & Neonatal Medicine. 29 (8): 1297–307. doi:10.3109/14767058.2015.1046828. PMID 26067262. S2CID 29501108.

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