How IVF works


In Vitro Fertilization (IVF)

Medically reviewed by Norbert Gleicher, MD, FACOG, FACS - Written by CHR Staff - Updated on Nov 15, 2014

How IVF Works

The first step is to determine whether IVF is appropriate for a patient, and if so, what protocol should be used, and whether special adjustments may be needed to address the patient's clinical circumstances. This is accomplished through some initial testing to determine the cause(s) of infertility. This diagnostic testing stage may include:

  • hormone tests such as AMH and FSH;
  • an evaluation of the uterine cavity and fallopian tubes, with HSN or HSG; and
  • semen analysis.

At CHR, the initial testing is taken very seriously; to us, it only makes sense to identify the problems before trying to tackle them. As a "fertility center of last resort," we see patients daily with a long history of failed IVF cycles at other centers. It is astonishing how many of these patients have infertility causes and/or related medical conditions affecting their fertility potential that were not identified, thus not addressed during the course of their previous IVF attempts.

Once the causes of infertility are identified and IVF is chosen as the plan of action, the basic flow of treatment is similar for most patients, although some patients do require additional interventions or adjustments.

Typical Steps of an IVF Cycle

 Stage 1: Hormone Suppression

Medications are administered over the course of about 21 days to suppress normal ovarian function

The first stage of IVF involves stimulating the ovaries so that multiple eggs mature. Normally, a woman produces one egg in each menstrual cycle, but with IVF, many follicles (small sacks in the ovaries that contain growing eggs) are produced with hormone stimulation and multiple eggs are obtained (usually 7-15). This ensures that a good number of embryos are produced after fertilization.
Typically one to three embryos are transferred into the uterus to establish a pregnancy. To achieve this, the female patient will need to take fertility medications to suppress her own hormones. This phase lasts for about 21 days. The drugs put the body into a temporary low-hormone state (similar to a short-term menopause), along with all of the side effects that might be expected such as hot flashes and mood swings.

 Stage 2: Ovarian Stimulation

Injectable fertility medications are administered for 8-12 days to stimulate the woman's ovaries to mature multiple eggs

Once the patient's own hormones have been suppressed, she can begin taking the medications that stimulate the ovaries and promote egg production. She may need to have injections daily for 8-12 days. The response of the ovaries will be carefully monitored using ultrasound scanning to see the size and number of developing follicles as well as blood tests. CHR physicians will modify this according to the way the individual patient's body responds to the stimulation.
Monitoring during this stimulation period is essential, because the ovaries sometimes respond too strongly to the medicines. This may result in the ovarian hyperstimulation syndrome (OHSS), which can cause a range of symptoms from mild abdominal pain to severe pain, vomiting, nausea and dehydration. On rare occasions, an IVF cycle has to be cancelled because of hyperstimulation. IVF cycles can also be cancelled if not enough follicles develop, or the follicles grow very poorly. CHR physicians strive to strike a balance between these two unfavorable outcomes, based on their decades of clinical experience and up-to-date knowledge of the medical literature.

 Stage 3: Egg Retrieval and Fertilization

Eggs are removed from the ovaries in a surgical procedure, then fertilized in a lab with the partner's or a donor's sperm

If all goes well, the next stage in an IVF cycle is egg retrieval (egg collection). This takes place when the ultrasound scan shows a sufficient number of large follicles. The patient takes an injection late at night to give the eggs in the ovaries the last 'push' towards maturity. Ovulation normally occurs 37-40 hours after this injection, so egg retrieval is scheduled to take place just before ovulation occurs (at about 34 hours).
The eggs are usually retrieved using a fine, hollow needle guided by ultrasound. Around the same time of the oocyte collection for the female patient, the male partner produces a semen sample. (Of course, we can work with frozen donor sperm as well.) The sperm is assessed and prepared for fertilization. As soon as the eggs are extracted from the ovaries, they are placed into an "embryo culture" medium with the sperm and then placed in an incubator overnight. The next day, the eggs are observed through a microscope to see if fertilization has occurred. The day after, cell division will have started and the embryo might now have two or four cells.

 Stage 4: Embryo Transfer

Embryos are selected and transferred into the woman's uterus through a small catheter inserted through the cervix

The embryos will be checked by our expert embryologists to ensure that they are developing normally and, if all is well, embryo transfer can take place. In most cases where PGD is not involved, embryo transfer is scheduled 3 days after the egg retrieval. The embryos, together with a tiny amount of nutrient fluid, are put into a catheter and placed into the uterus through her cervix with a special ultrasound guidance by one of our IVF doctors. By transferring one or two embryos we reduce the risk of a multiple pregnancy. Occasionally, in older patients, we transfer more embryos. If there are "extra" embryos of good quality, these can be frozen and stored for use in a future treatment cycle if needed.
The embryo transfer procedure is critical; the physician's skill in placing the embryo(s) in the optimal location in the uterus has an impact on the likelihood of eventual pregnancy. The procedure is short and generally painless. Afterwards, the woman will be advised to rest for a short time and then go home and "carry on as normal."

 Stage 5: Pregnancy Testing and Confirmation

Approximately two weeks after the transfer is complete, a blood test will be done to detect the pregnancy. If this is positive, an ultrasound will be performed for further confirmation several weeks later

It will be about two weeks before a pregnancy test can be done, and this waiting is one of the most stressful times of the cycle. During this time, the female patient will be prescribed progesterone, which is needed to provide hormonal support to a pregnancy.
If the pregnancy blood test is positive, we will confirm this with a few more blood tests. Then an ultrasound scan a couple of weeks later will identify a normal pregnancy in the uterus and the heartbeat of the new embryo. If all is developing normally, the newly pregnant patient will be referred back to her obstetrician to make the transition to prenatal care.
While the in vitro fertilization procedure described above sounds simple, in reality, IVF is a complex and emotionally demanding process, as many of our patients can tell you. It can take between six weeks and two months on average for a single treatment cycle and most couples find it both physically and mentally draining. CHR staff members' extensive experience with couples going through IVF treatment allows us to provide all the support needed to assist individuals during this emotional time.

Become a Patient


Norbert Gleicher, MD

Norbert Gleicher, MD, FACOG, FACS

Norbert Gleicher, MD, leads CHR’s clinical and research efforts as Medical Director and Chief Scientist. A world-renowned specialist in reproductive endocrinology, Dr. Gleicher has published hundreds of peer-reviewed papers and lectured globally while keeping an active clinical career focused on ovarian aging, immunological issues and other difficult cases of infertility.

Follow on LinkedIn    

Watch his videos on YouTube    




Center for Human Reproduction
21 E 69th Street
Upper East Side

New York, NY 10021
Phone: 626-385-7918
Fax: 212-994-4499

Office Hours

Get in touch