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Introduction to ART (Assisted Reproductive Technology): From Stimulation to Egg Retrieval

Updated: Jun 30, 2023

Assisted reproductive technology, ART for short, describes technologies to treat infertility.

This article is pending medical review.


Written by Yasemin Kaya and Sophie Oppelt

Reviewed by Alizeh Ahsan and Julian Zeegers

Edited by Juliëtte Gossens


ART, by definition, refers to any fertility treatments that involve the handling of eggs or embryos. Generally, this happens through the surgical removal of eggs from the person’s ovaries, merging them with sperm at the laboratory, and then transferring them back to the person's womb. They can also be given to another person wishing to become pregnant for a so-called egg donation. (1, 2)

Below, we describe the steps involved in ART.

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Step 1: Ovarian stimulation

The ART process starts with stimulation of the ovaries so that multiple follicles develop. Normally, each month, only one follicle (which is a small fluid-filled sac inside the ovaries) develops and matures fully to release one egg cell for fertilization. In ovarian stimulation, candidates get a course of hormones injected to stimulate multiple follicles to produce egg cells. The injected hormones are normally also produced by the body throughout the menstrual cycle, but in this case hormone levels are kept above a certain threshold so that multiple follicles can mature in one menstrual cycle instead of only one. The treatment course starts two to three days after menstruation until two weeks after menstruation, when the egg cells are mature. Sometimes a period of pre-treatment may be needed to prepare for ovarian stimulation. During this period, ultrasound scans monitor the follicles’ development, and your doctor might adjust the dose of the drugs.

But why do we need multiple egg cells? There are several reasons for this: firstly, the egg cells are tested and only the best quality ones are used in further steps. Secondly, multiple egg cells are fertilized (see below), but only some of those are suitable to implant back into the uterus. Thirdly, the first round of implantation might be unsuccessful, and more rounds of ART can be needed to become pregnant. Therefore, egg cells and embryos can be frozen, so parents do not have to go through all the same steps again. (2-4)

Step 2: Triggering ovulation

When follicles are mature, they burst and release the egg cell, which is known as ovulation. This happens in response to high levels of luteinizing hormone in a short amount of time, which can be mimicked by a trigger injection. Multiple hormones can be used, and it depends on your personal situation and doctor what exactly the injection contains. Within the next 36 hours, the egg cells are collected, which is elaborated in the next step on. (2- 4)

Step 3: Retrieving your egg cells

Just before the follicles burst and release the egg cells, they are collected by your doctor. This is done by inserting a thin needle through the vaginal wall into the ovaries, sometimes under sedation and with ultrasound guidance. Once the needle has entered the follicle, the follicular fluid containing the egg is collected in a tube. Usually around 20 egg cells are removed one by one and the whole procedure takes about one hour. The collected liquid is analyzed, and the egg cells are selected from the collected sample. Sometimes some of the egg cells are frozen to be used later. (2- 4)

Usually on the same day, the sperm cells are also collected from the ejaculate (semen) or through another appropriate procedure.

Step 4: Fertilizing your eggs in the lab

The sperm and egg cells are then

combined in a laboratory to create an embryo.

This fertilization step can be accomplished with different procedures; the most common ones are in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). Read the In vitro fertilization (IVF) vs. Intracytoplasmic sperm injection (ICSI) article for more information on those procedures and the embryo transfer after. (2- 4)

What are the risks involved in ART?

Even though the ART procedure has been made a lot safer over the past decades by introducing new and more advanced safety protocols, risks linked to infertility treatment are still present. You should therefore be sufficiently informed before starting the treatment.

Some general risks associated with ART are similar to most procedures for which the body is entered (such as surgery), and include vaginal bleeding (in 1.4%-18.4% of patients), abdominal bleeding (0.05%-0.2% of patients), infections (0.1%-0.6%), damage to close-by organs (such as the bladder or intestines), and thrombosis (0.1%-0.5%). (5, 6)

Other risks are specifically associated with ART treatment and include placenta disorders. Studies (7) indicate that conditions like pre-eclampsia (which you can read about here) seem to be more common following ART cycles, but more research is needed to properly clarify the relationship between ART and placenta disorders.

Ovarian hyperstimulation syndrome (OHSS) is another potential complication. During controlled ovarian stimulation, such as during ART when injecting hormones to release egg cells, it is possible to cause a hyperstimulation of the ovaries. This can cause ovarian pain, which you may feel as pain in the pelvis or lower abdomen, and swelling. This reaction is mainly associated with patient characteristics such as age and hormonal profile, and can be prevented by your doctor taking an accurate medical history and making sure you undergo specific laboratory examinations (such as blood tests). In case hyperstimulation still occurs, the hormone injection can temporarily be stopped, and medications can be given to reverse the disease. (2, 4)

Your personal risks depend on many different factors. Therefore, it is important that your doctor knows about your medical history and your family history to properly assess the risks associated with ART treatment, to keep an eye on the development, and if needed to intervene accordingly. This way, your risk can be kept to a minimum.



  1. NHS. Treatment Infertility. Available from: [Accessed May 25th, 2022]

  2. Carson SA, Kallen AN. Diagnosis and Management of Infertility: A Review. JAMA. 2021;326(1):65–76. DOI:10.1001/jama.2021.4788

  3. Racca A, Drakopoulos P, Neves AR, Polyzos NP. Current Therapeutic Options for Controlled Ovarian Stimulation in Assisted Reproductive Technology. Drugs. 2020;80(10):973-994. DOI: 10.1007/s40265-020-01324-w.

  4. Barzier Y. Infertility in men and women. Available from: [Accessed May 25th, 2022]

  5. Bhandari HM, Choudhary MK, Stewart JA. Complications of assisted reproductive technology treatment and the factors influencing reproductive outcome. Obstet Gynaecol. 2018;20:177-86. DOI: 10.1111/tog.12504

  6. Grandone E, Villani M. Assisted reproductive technologies and thrombosis. Thrombosis Research. 2015;135(Suppl.1):S44-S45. DOI: 10.1016/S0049-3848(15)50441-6

  7. Kenigsberg S, Bentov Y. Does contemporary ART lead to pre-eclampsia? A cohort study and meta-analysis. J Assist Reprod Genet. 2021 Mar;38(3):651-659. DOI: 10.1007/s10815-021-02061-z.

Please note: the information we provide to you here is for educational purposes only. If you’re experiencing any discomfort or have any complaints or questions about your health, please contact your doctor or other relevant health professional. We don’t provide medical advice.


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