Why is the hormone oxytocin used to stimulate labour?

By (biologist specialized in clinical & biomedical laboratory), (embryologist) and .
Last Update: 02/06/2023

Oxytocin is a hormone secreted by the mother's brain during gestation that is necessary to trigger labor. The name of this hormone comes from Greek and its meaning is "rapid delivery". Therefore, its function is to control the rhythm of labor and to facilitate lactation.

When a woman goes into labor, her oxytocin levels increase. In this way, the oxytocin receptors located in the uterus are stimulated, producing contractions of the uterine muscle.

Nevertheless, some women require synthetic oxytocin to improve the rhythm of contractions or if labor needs to be induced. In addition, artificial oxytocin can also be administered after delivery in an attempt to stop bleeding.

What is oxytocin?

Oxytocin is a hormone generated in the hypothalamus and goes to the pituitary gland. This molecule can behave as a hormone, but also as a neurotransmitter.

Oxytocin is responsible for triggering labor and dilating the cervix causing uterine contractions. In addition, oxytocin is also involved during lactation, as it is the hormone that causes milk to be ejected from the breasts.

However, these are not the only functions of oxytocin. This hormone is essential for sexual and organ arousal in women, but also in men. Oxytocin levels increase during sexual intercourse and especially after orgasm. For this reason, oxytocin is also known as the love hormone.

Uses of oxytocin

Natural oxytocin secretion occurs when a woman goes into labor. Sometimes, however, specialists opt to inject synthetic or artificial oxytocin for better control of uterine contractions.

For this reason, the possible uses of synthetic oxytocin are as follows:

  • Initiate labor when it is considered that continued gestation could be risky and, therefore, it is better to induce labor as soon as possible.
  • Stimulate labor when uterine dynamics are insufficient. This is intended to ensure that the birth of the baby occurs within the time frame that is considered safe for the mother and fetus, without lengthening.
  • To evaluate the intrauterine fetal status and check fetal well-being, known as the pOSSE testor oxytocin test.

One of the doubts associated with the administration of oxytocin at the time of delivery is whether its application will cause more painful uterine contractions. The truth is that synthetic oxytocin causes contractions similar to those produced spontaneously by natural oxytocin.

Artificial oxytocin is administered when uterine activity is insufficient, so pain will come on suddenly. However, the contractions of the uterus and their corresponding discomfort will be the same as if the woman had naturally produced the correct amount of endogenous oxytocin.

How is synthetic oxytocin administered?

This artificial hormone can be administered at any stage of labor. It is administered through a dropper and in a controlled manner. In addition, the dose of artificial oxytocin injected into the woman is increased, as is the speed of the drip until the appropriate uterine contractions are achieved.

Regarding the amount of oxytocin to be injected into the woman, this will depend on each situation and the characteristics of each patient. The work protocols of each center must also be taken into account.

For example, there are protocols that recommend injecting 1-2 mIUI per minute of oxytocin initially and increasing the dose. On the other hand, if the aim is to stop postpartum hemorrhage, the patient will be given between 2-10 mIUI if intramuscularly and once the placenta has been expelled.

In any case, the obstetrician keeps an eye on uterine contractions, maternal blood pressure and fetal heart rate at all times when administering exogenous oxytocin to the patient.

Does it have negative effects?

Oxytocin, like any drug, can cause adverse effects after administration to induce labor or stop postpartum hemorrhage.

A possible side effect of oxytocin is urinary retention, although it will depend on the dose administered. In addition, if the patient develops a hypersensitivity reaction to oxytocin due to a high amount of the hormone, hypertonic uterine contractions of great intensity and prolonged duration may occur. This could cause adverse reactions such as: cervical laceration, postpartum hemorrhage, pelvic hematoma, etc. However, this is not the norm.

On the other hand, uterine hyperstimulation with oxytocin could have fetal consequences. For example, if artificial hormone doses are excessive, transient oxygen deficiency could occur. This is usually easily resolved by discontinuing the administration of oxytocin.

Contraindications of the use of oxytocin

One of the situations in which a pregnant woman should not be injected with oxytocin is if she is allergic to this drug. In addition, if there is In addition, oxytocin should also not be used in the following cases:

  • There is evidence of fetal distress.
  • Abnormally positioned fetus.
  • Placenta previa.
  • Uterine prolapse or cephalopelvic disproportion.
  • Major surgery of the cervix or uterus.
  • Herpes infection.

In addition, oxytocin should be used with more caution in twin deliveries and/or in women with heart disease. In cases of coronary or renal insufficiency, or hypertension, the dose of oxytocin injected should be low.

FAQs from users

Why is oxytocin known as the love hormone?

By Marta Barranquero Gómez B.Sc., M.Sc. (embryologist).

Oxytocin is called the love hormone because of its effect on sensuality, affectivity and sexuality. Oxytocin is associated with pleasure, hence its name.

How long does artificial oxytocin take to work?

By Marta Barranquero Gómez B.Sc., M.Sc. (embryologist).

Oxytocin used to induce labour is slow-acting. Therefore, it is necessary to wait at least 20-40 minutes to observe its effects.

Once this time has elapsed, the specialists will assess whether the intensity of the uterine contractions is correct or whether it is necessary to increase the dose of synthetic oxytocin.

What is induced labor?

By Andrea Rodrigo B.Sc., M.Sc. (embryologist).

Induced labor occurs when, for various reasons, it is necessary to induce labor by means of medication. It is performed when, by medical indication, it is recommended to terminate the pregnancy due to the possibility of risk to both the mother and the fetus.

The pregnant woman receives intravenous oxytocin, which will cause regular uterine contractions that will favor the dilation of the uterus and thus the expulsion of the fetus.

There are also situations in which, in addition to the administration of oxytocin, artificial rupture of the amniotic sac is performed. In this way, the baby's head is pushed down and presses on the cervix.

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FAQs from users: 'Why is oxytocin known as the love hormone?', 'How long does artificial oxytocin take to work?' and 'What is induced labor?'.

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Authors and contributors

 María Rodríguez Ramírez
María Rodríguez Ramírez
Biologist specialized in Clinical & Biomedical Laboratory
Bachelor's Degree in Biology and Postgraduate Degree in Clinical & Biomedical Laboratory by the University of Valencia (UV). Writer of scientific contents from the field of Biology and Human Reproduction. More information about María Rodríguez Ramírez
 Marta Barranquero Gómez
Marta Barranquero Gómez
B.Sc., M.Sc.
Graduated in Biochemistry and Biomedical Sciences by the University of Valencia (UV) and specialized in Assisted Reproduction by the University of Alcalá de Henares (UAH) in collaboration with Ginefiv and in Clinical Genetics by the University of Alcalá de Henares (UAH). More information about Marta Barranquero Gómez
License: 3316-CV
Adapted into english by:

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