The primary difference between an in vitro fertilization (IVF) cycle and a regular menstrual cycle is that ovulation doesn’t take place during an IVF cycle. In an IVF cycle, the eggs are retrieved at the point of maturation and are fertilized in the IVF lab to create embryos. The embryo(s) is then transferred to the uterus.

Below you will find detailed information on how a regular menstrual cycle and IVF cycle works.

WHAT HAPPENS DURING A REGULAR MENSTRUAL CYCLE?

During a woman’s normal monthly reproductive cycle, her ovary grows and matures a single egg inside an egg follicle. When her hormones reach a certain level, the mature egg is released and becomes available to be fertilized.

At the same time, hormonal changes prepare the uterus for pregnancy. If ovulation takes place and the egg isn’t fertilized, the lining of the uterus sheds through the vagina (referred to as a “period”).

The typical menstrual cycle is 28 days long, but each woman is different. The length of your menstrual cycle may differ from month-to-month. Your periods are still considered “regular” if they usually come every 24 to 38 days. This means that the time from the first day of your last period up to the start of your next period is at least 24 days but not more than 38 days.

WHAT HAPPENS DURING AN IVF CYCLE?

During an IVF cycle, a woman will self-administer injectable fertility medications for approximately 7-10 days (the length of stimulation depends on the patient’s personalized protocol), which stimulate the ovaries. Stimulating hormones help the follicles grow and release multiple mature eggs at one time. An antral follicle count is performed during your initial evaluation at CCRM, which will provide a general predictor for how you should respond to stimulation.

During your monitoring appointments, the ultrasound will measure how many follicles are growing and how big each follicle is. Our goal is to safely grow as many follicles as possible to about 18 millimeter in size, at which time you will be instructed to administer a medication called a trigger shot, which will release the mature eggs to be retrieved by your doctor.

Depending on the type of trigger shot used, you will come to our clinic 34-36 hours following the trigger shot for your egg retrieval. During the egg retrieval, you will be under anesthesia or conscious sedation while the doctor collects your mature eggs during a minor surgical procedure, which is performed vaginally and under ultrasound guidance. Since you will be sedated, you must have someone come with you for the procedure and remain with you until the following day.

Around the same time as your egg retrieval, if you have a male partner, he will provide a semen sample or previously frozen sperm samples will be thawed and an embryologist will prepare sperm. Your retrieved eggs will then be fertilized in the IVF lab.

Your doctor will discuss the pros and cons of fresh versus frozen embryo transfer and what is best suited for your specific situation. If preimplantation genetic testing, also known as PGT, of embryos is to be performed, frozen embryo transfer is required. PGT provides many benefits, including the prevention of passing on genetic diseases, such as hereditary cancer, as well as reducing your chance of miscarriage. The majority of IVF cycles at CCRM are frozen embryo transfers for this reason, along with more recent data suggesting that this approach may be more successful.

If a fresh embryo transfer is planned, this will be performed either three or five days after the egg retrieval. Hormonal support for the embryo will be initiated prior to that time.

If a frozen embryo is planned, in an agreed upon cycle following your egg retrieval, you will begin uterine preparation to help with implantation. An additional benefit of using frozen embryos is that your hormone levels have time to return to normal following stimulation before you start uterine preparation medications. Once your hormones have returned to normal, you will receive a new treatment calendar with medication instructions from your nurse. Your doctor will also call you with results from any preimplantation genetic testing you may have completed and will discuss plans for which embryos would be the best choice for transfer.

On the day of your embryo transfer, your embryos are thawed, and you will return to our clinic where the doctor will place a speculum and introduce one or multiple embryos into your uterus using a small, flexible catheter under ultrasound guidance. This minor procedure is relatively pain-free and typically does not require sedation. Valium may be administered as a muscle relaxant. Following your transfer, you will return home and rest for at least 24 hours. You can return to work and most other normal daily activities the following day. Approximately 9-14 days later, you will return to CCRM to complete a blood pregnancy test to confirm the outcome of the transfer.