What Is Controlled Ovarian Stimulation?

By (embryologist), (gynecologist) and (babygest staff).
Last Update: 07/05/2019

Ovarian stimulation is one of the main steps in assisted reproduction techniques such as artificial insemination or in vitro fertilization (IVF). This is a process whereby the patient or donor, depending on each case, receives injections of hormonal medication to stimulate and control ovulation.

In this article we will talk about the ovarian stimulation process, its objective, the medications used and the symptoms that can be derived.

What is the ovary stimulated for?

A woman naturally releases an ovum or egg each menstrual cycle. By the action that gonadotropins (released by the pituitary gland) exert on the ovary, a group of follicles begins to develop, but only one of them will release an egg, that is, ovulation will only occur in one of them. The rest of the eggs degenerate along the way. It should be remembered that follicles are structures of the ovary where the eggs mature.

With the hormonal medication of ovarian stimulation, it is intended that virtually all the follicles that began the path of maturation reach the goal: ovulation. In this way, we are able to extract more mature eggs by puncture. In order to do this, it is necessary to control oocyte development, as the eggs must be removed from the ovary when they are in an advanced stage of maturation, but before they ovulate spontaneously and cannot be located.

Hence the importance of performing ovarian stimulation in a controlled and personalized way depending on the response of each woman to the injections of hormonal medication administered.

The number of eggs obtained depends on each woman, about her age and even how the stimulation cycle has gone, but between 6 and 15 eggs can be considered as normal.

All that has been explained above is what happens in in vitro fertilization processes. However, in the case of artificial insemination, since fertilization occurs in the female organism, ovarian stimulation is much gentler.

The objective in this case is not the maturation of a large number of eggs but to control and ensure that the ovulation of one or two eggs occurs. This allows to deposit the sperm at the right time and thus increase the probability of fertilization and, therefore, pregnancy.

Medications for ovarian stimulation

Most medications are given through a daily subcutaneous injection for a variable period of time (between 7 and 15 days). It is not complicated and in the clinic they teach the woman how to do it from home. The area of application is the abdomen.

The treatment must be personalized. Therefore, the dose to administer will vary depending on various factors such as the age of the woman, her weight, her health status, previous stimulations, etc..

The doctor indicates the appropriate dose and monitors it throughout the cycle to check how the ovary is responding and, if necessary, readjust the dose.

There are several ovarian stimulation protocols. However, generally speaking, we can say that medication for ovarian stimulation consists of three fundamental steps:

Induce ovarian maturation

The woman administers to herself drugs that replace the action of hypophysial gonadotropins, which are hormones that exert their function on the ovary, and favor the maturation of the eggs. These are the hormones FSH (follicle stimulating hormone) and LH (luteinizing hormone).

Block natural control

GnRH analogues are given either agonists or antagonists. These are drugs that simulate the action of GnRH, a hormone produced in the hypothalamus that promotes the natural release of FSH and LH. This medication blocks the action of natural GnRH, which allows the hormonal cycle to be controlled exogenously.

Stimulate ovulation

Ovulation is usually triggered by the administration of human chorionic gonadotropin (hCG). This hormone induces ovulation about 36 hours after administration, so in cases of IVF, the puncture should be performed a few hours earlier. In the case of AI, ovulation should approximately coincide with the introduction of sperm.

GnRH agonists can also be used to induce ovulation.

Ultrasound control

As we have already mentioned, it is fundamental to carry out an adequate follow-up of the ovarian stimulation process by the specialist in order to avoid possible complications and risks.

During the time that the woman is administering the medication, she must undergo continuous gynaecological check-ups so that the doctor can assess the response to the treatment and modify it if necessary.

During these visits, two main tests are carried out:

  • Blood tests: Each mature egg is known to release approximately 200-300 pg/ml of estradiol. Therefore, measuring the blood estradiol value can help to estimate the state of follicular maturation.
  • Transvaginal ultrasound: by means of a vaginal ultrasound the specialist can visualize the ovary and study its maturation. This test measures the number of growing follicles as well as their size.

This monitoring allows to schedule the right day for puncture or insemination.

Symptoms and Side Effects

Ovarian stimulation is a hormonal treatment that, although accompanied by an exhaustive follow-up, can lead to certain symptoms of greater or lesser severity.

It is most common for a woman to have the side effects of menstruation, but with greater intensity. Some examples are: abdominal swelling, vaginal dryness, increased fluid retention, heaviness in the legs, mood swings, sensation of pressure in the ovaries, irritation in the injection area, etc..

More serious or high-risk consequences such as the following could also result:

  • Multiple pregnancy. The pregnancy of twins or triplets is more risky and harmful to the health of both the pregnant woman and the babies.
  • Ovarian hyperstimulation syndrome. It occurs when a woman's body responds exaggeratedly to the medication given. The problems that can result from this are severe headache, vomiting, abdominal swelling, cramps, diarrhea, damage to the ovary, respiratory complications, and so on. You can read more about this syndrome here: What is ovarian hyperstimulation syndrome?

Ovarian stimulation in surrogacy

Surrogacy is a reproductive process whereby a woman offers to gestate the child of another woman, man or couple.

It is usually carried out by in vitro fertilization, with the only difference that the embryos obtained are transferred to the uterus of the surrogate mother instead of to the uterus of the future mother.

In this technique, the ovarian stimulation process is carried out by the future mother of the baby, i.e. the intended mother. She will be the one who, preferably, provides the eggs and, therefore, the one who undergoes ovarian stimulation and puncture.

If the mother cannot provide her eggs, a donor will do so and it will be she who undergoes ovarian stimulation treatment to obtain a greater number of eggs.

In surrogacy it is tried to avoid that the surrogate is the one who, in addition to providing her ability to gestate, provides the genetic endowment (eggs). This reduces, as much as possible, her involvement with the future baby. In addition, the possible risks for her are also reduced.

FAQs from users

What does IVF ovarian stimulation entail?

By Dr. Joel G. Brasch (gynecologist).

Ovulation induction for IVF entails administering gonadotropins with a GnRH agonist or antagonist to allow for the development of multiple eggs and prevent premature ovulation. The stimulation is monitored with blood work and ultrasounds. Hormone levels are measured with the blood work (estradiol, progesterone, LH) and the size of the follicles is measured to ascertain oocyte maturity. When a cohort of follicles are developed a trigger injection is given, either HCG or Leuprolide acetate, to start the process of ovulation. A trans vaginal oocyte retrieval is then performed 35-36 hours later.

Does ovarian stimulation bring menopause forward?

By Andrea Rodrigo (embryologist).

No. With ovarian stimulation we simply rescue those eggs that were destined for atresia or degeneration but we do not make the eggs that were going to ovulate in later cycles mature before their time.

For this reason, ovarian stimulation does not pose a risk to a woman's own fertility.

Do medications for ovarian hyperstimulation make you gain weight?

By Andrea Rodrigo (embryologist).

The medication to stimulate ovarian maturation is hormonal and its side effects include swelling and fluid retention. This can lead to a slight temporary weight gain. In any case, after treatment, the woman will return to her usual state.

Could ovarian stimulation be done with pills instead of injections?

By Andrea Rodrigo (embryologist).

With the exception of Synarel, which is nasal, the rest of the medication for ovarian stimulation is administered subcutaneously and not orally. Therefore, no, it would not be possible to stimulate the maturation of the ovary with pills.

Suggested for you

We have discussed the phases of medication for ovarian stimulation. If you want more details about this process you can consult this link: What Medications Are Used for Ovarian Stimulation?

We have also indicated that this treatment is carried out in both IVF and artificial insemination, although with slight variations. Do you want to know the differences between the two techniques? Discover them in this article: Assisted Reproductive Technology (ART) – Techniques Used in Surrogacy

On the other hand, we have commented that, in surrogacy, it is the future mother who undergoes this treatment and not the surrogate, who must follow other procedures. If you want to know more about the role of the surrogate in the surrogacy process, we recommend you to read this article: What Is a Surrogate Mother? – Everything You Should Know.

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Authors and contributors

 Andrea Rodrigo
Andrea Rodrigo
Bachelor's Degree in Biotechnology from the Polytechnic University of Valencia. Master's Degree in Biotechnology of Human Assisted Reproduction from the University of Valencia along with the Valencian Infertility Institute (IVI). Postgraduate course in Medical Genetics. More information about Andrea Rodrigo
Dr. Joel G. Brasch
Dr. Joel G. Brasch
Dr. Joel Brasch is the Medical Director of Chicago IVF, founded in 2005. He is board certified by the American Board of Obstetrics and Gynecology, and has over 25 years of direct experience in fertility treatment and reproductive care. He is also the Director of Mount Sinai Medical Center’s Division of Reproductive Endocrinology and Infertility. More information about Dr. Joel G. Brasch
Adapted into english by:
 Marie Tusseau
Marie Tusseau
Babygest Staff
Editorial Director of Babygest magazine in French and English. More information about Marie Tusseau

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