Embryo Transfer

Top Questions About Embryo Transfers, Answered By Dr. Jaime Knopman, MD


5 min read

So much of the fertility content on the internet revolves around IVF and the ovarian stimulation process, but we wanted to know more about what happens next, after the embryos are created. So, we asked Dr. Jaime Knopman to fill us in on some details about the embryo transfer process.

Dr. Jaime Knopman

Dr. Knopman is a board-certified reproductive endocrinologist practicing at CCRM in New York City. She has earned recognition on esteemed lists such as New York Magazine’s Top Doctors and the peer-nominated Castle Connolly Top Doctors list. With extensive experience in treating various infertility conditions, we are delighted to share her knowledge on embryo transfers.

Berry: Can you quickly tell us a bit about the embryo transfer procedure and what someone should expect that day?

Dr. Knopman: Embryo transfers are the "easy" part of the IVF experience. While they are the finale of the big event, they are actually pretty painless and fast. They take no more than 10 minutes and most patients get up immediately after and walk home! The pregnancy test is generally performed 9 days later. 

How clinics perform transfers in the OR or in an exam room, with partners present or without, with valium or without, and with acupuncture or without can vary! In our center, we perform all transfers in exam rooms with partners! We also offer every patient valium and acupuncture. There can be a lot of anxiety leading up to this day and I am a huge fan of valium — it will relax you and your cervix. If you elect to add acupuncture it is performed pre and post transfer. There are no needles; just the speculum. 

We have patients arrive about 30 minutes before their transfer time. The procedure itself takes no more than 10 minutes and then we have you hang with us for about 30-45 minutes after. If you get acupuncture pre and post transfer, it will add on about 40 minutes total (20 pre and 20 post).

Berry: We know that there are both fresh and frozen embryo transfers, but frozen embryo transfers seem to be becoming the norm. What are the advantages of a frozen embryo transfer?

Dr. Knopman: Yes! Fun fact: in the entirety of my career I can count on two hands the number of fresh transfers I have done. Frozen transfers are a HUGE plus for three reasons: 

  1. Embryos can undergo genetic testing and therefore we will know the viability of the embryo and its chromosome complement before the embryo is transferred, which increases success rates DRAMATICALLY, decreases miscarriage rates, and reduces the incidence of twins.

  2. The incidence of Ovarian Hyperstimulation Syndrome (OHSS) is significantly reduced because when a patient gets pregnant in a fresh transfer at the end of an IVF cycle the HCG from the pregnancy sends signals to the ovaries that keep them enlarged as well as allowing hormonal fluctuations to persist.

  3. Babies born after frozen embryo transfers where hormone levels have been allowed to return to baseline seem to do better than those from stimulated cycles.

Berry Note: There are two main types of embryo transfers: fresh and frozen.

In a fresh transfer, you begin taking estrogen and progesterone the day after your egg retrieval, with the embryo transferred into your uterus typically within 3-5 days.

Frozen embryo transfers (FET) can be either medicated or natural. Medicated FETs involve using hormone medications to control the uterine lining's growth and preparation for embryo implantation. Natural FETs utilize the menstrual cycle's own hormones to grow and prepare the uterine lining via follicle growth, estrogen production, and ovulation.  Sometimes, natural FETs are supplemented by medications like a trigger shot and additional progesterone.

As Dr. Knopman noted, frozen transfers are increasingly popular, especially when a patient wishes to conduct genetic testing of embryos or plan for additional children in the future. So we asked Dr. Knopman to tell us more about frozen embryo transfers.

Berry: Do you find that more people do a medicated frozen embryo transfer versus a natural frozen embryo transfer cycle? And are there reasons why certain people may be better suited for one versus the other?

Dr. Knopman: I do find that more people do medicated frozen embryo transfer cycles, but I am NOT one of those people. 90 plus percent of my transfers are natural or modified natural frozen embryo transfer cycles. I believe that the natural FET is way easier for patients (no intramuscular shots) and better for the pregnancies that occur (less risks during pregnancy). If a patient is in menopause or does not get regular periods then we may need to do the medicated embryo transfer.

Berry: Why is the timing of the embryo transfer important? Are there any people who fall outside of the standard timing?

Dr. Knopman: The timing is very important! The uterus and embryo need to be in sync for implantation to occur. While it doesn't come down to minutes, it does come down to hours. There are people who fall outside of the standard progesterone timing although who these people are can be hard to identify. Sometimes if patients fail transfers with traditional progesterone timing we will do a test known as an ERA (Endometrial Receptivity Array) to see if they need more or less days of progesterone. Unfortunately, most trials have not shown the ERA to be well validated. It is a hard decision as a patient and a clinician if and when to perform the ERA.

Berry: Can you explain more about the ERA (Endometrial Receptivity Array) test and your thoughts around it?

Dr. Knopman: ERA is the endometrial receptivity array. It is done on the standard day of progesterone to see if a patient needs more or less hours or days of progesterone than the typical protocol. I am honestly not a huge fan because it has not been well validated. However, I will do it in select situations — if a patient has transferred chromosomally intact embryos into a beautiful uterus and implantation has not occurred, I will perform the test. I want to make sure I have covered all bases before moving on to a gestational carrier. 

Frozen embryo transfer is the next step after creating the embryos through IVF. You and your doctor can discuss which type of cycle and what testing is best for you based on your personal health history and infertility diagnosis. 

For more information on embryo transfers read our articles on Frozen or Fresh Embryo Transfer — What is the Difference and What is Right for You? and What to Expect on Embryo Transfer Day.

If you want to see more from Dr. Knopman, you can find her @afertilefuture on Instagram. She also co-founded East Meets West Fertility, which is a website focused on providing accessible, trustworthy, and approachable fertility education to all.