IVF 101- Part III: Fertilization, Embryo Transfer, and the Pregnancy Test



This is part three of my IVF 101 Series, where I will describe the basics about the fertilization process, embryo transfer, and the that time between the embryo transfer and your pregnancy test call the “Two Week Wait”.

In short,  IVF consists of a woman taking drugs to assist in producing eggs, those eggs are extracted, fertilized, and put back into uterus where hopefully it will implant and become a viable pregnancy. Click here to reach Part I of the series, What the Heck is IVF?, and click here to reach Part II of the series, Diagnostics, Protocols and Egg Retrieval.


(How an egg becomes an embryo)

Following the egg retrieval the embryologist will now have eggs and sperm, the possible beginnings of your future baby.  The eggs and sperm will be mixed together and the embryologist will check in the morning to see how many eggs fertilized.  It is important to note that it’s very common for some of the eggs not to fertilize, so you may have fewer embryos than eggs.

In cases where the man’s sperm may have issues with motility (ability to swim around and penetrate the egg), to increase the chances of fertilization a procedure called intracytoplasmic sperm injection (ICSI) may be used.  During ICSI, the embryologist will insert the sperm into an extremely small needle type instrument that is used to penetrate the surface of the egg, where the sperm is then injected inside.

Keep in mind, it is a possibility that none of the eggs fertilize, which has happened to me on two separate occasions.   Those results can be terribly sad and frustrating after you have invested your time, emotions and money in IVF, but that doesn’t mean that it can’t work next time.

So how do they know whether the egg has fertilized?  The embryologist will check the eggs the day after your egg retrieval to see if cells have started to divide into two or more cells.  That is the beginning of your embryo. Over the next several days, the embryologist will continue to monitor the embryos and the cells should continue to divide exponentially.   If the embryo continues to grow to day five, it typically becomes something called a “blastocyst”, somewhere around 100 cells or so.

Within the blastocyst, there are two types of cells. In the interior is the inner cell mass, a portion of which will begin to divide at a very rapid pace and become the fetus.   Surrounding this is a single layer of cells called the torophoblast that will combine with the endometrial cells of your uterus to become the placenta.

If your doctor is concerned about possible genetic issues, he or she may recommend that your embryos be sampled for genetic testing and cryogenically frozen until you receive the results.   Doctors may be more likely to recommend this if a woman has a history of repeated miscarriages, or a woman is over 35 years of age.


(Supplemental Hormones, How Many Embryos to Transfer, and Transfer Procedure)

Supplemental Hormones.

While your eggs are busy growing into embryos, you will start taking hormones to set the stage for embryo transfer.

Doctors want to make sure that you have sufficient estrogen and hormone levels to sustain a pregnancy, and that your uterine lining is the right thickness.  The estrogen is usually in pill form, while the progesterone is initially taken via an intramuscular shot in the buttocks.  My husband gave me the progesterone injections during our first several IVF cycles, but eventually I learned to give them myself.  Admittedly the needles can look a little bit intimidating, but you will get used to it.  If you are nervous about this shot, sometimes icing the area beforehand can help alleviate any discomfort.

As the embryologists are watching your embryos develop, they will begin to assess their quality.  Your doctor will transfer your embryo or embryos somewhere between 3 and 5 days following your egg retrieval.  If you have fewer or poorer quality embryos, your doctor may elect to do an embryo transfer earlier, but if you have many embryos or embryos of very good quality, your doctor may elect to wait until Day 5 for the transfer.

How Many Embryos to Transfer? 

Every doctor is different, but typically they will transfer between 1-3 embryos at a time, though recently many doctors are leaning toward transferring only 1-2 embryos at a time.  More embryos = greater chance of getting pregnant, though getting pregnant doesn’t necessarily result in successful full term pregnancies.  In making this decision, your doctor will consider the quality of the embryos (weighing the chance that each will result in a pregnancy), and whether you have any conditions that may be problematic should you become pregnant with twins.   (I happen to have a uterine condition where they do not think my body could carry twins successfully, so I only ever transfer one embryo.)   Talk with your doctor about this prior to the day of transfer so they can take your desires and concerns into consideration when recommending the number to be transferred.

Transfer Procedure

Before the transfer, the doctor will likely give you a photo of your embryo(s) being transferred, discuss the quality of the embryo(s), and describe the process to you.

During the transfer process, you will lay on a table with your feet in stirrups and the doctor will insert a speculum.  After you are prepped, the doctor will insert a small catheter up into your uterus.  They will determine the exact spot they want to place the catheter by using an external ultrasound machine on your lower abdomen.  When the catheter has been guided into the desired location, the embryologist will put the embryo in the end of the catheter and fluid will be used to help push the embryo up into your uterus.  You will likely be able to watch all of this taking place on the ultrasound as well.  Once the procedure is over with, the catheter is checked again to confirm the embryo is successful at home in your uterus.

Below are a few other random things that you should expect:

  • Full Bladder. About an hour before your transfer, you will need to drink enough water so that you feel like you need to use the bathroom without being uncomfortable.  The full bladder helps press against the uterus to straighten it vertically for easier insertion of the catheter, and it helps with the visualization of the ultrasound process.  Admittedly, drinking the right amount of water is a little difficult to judge at times, but two small bottles of water or one large bottle of water usually does the trick for me.   Yes, you will feel a tad bit uncomfortable while you are waiting, but the transfer is over pretty quickly.
  • Valium. Your doctor will also likely have you take a Valium right before the transfer.  This will help the uterus remain calm and not spasm during the transfer process, improving your chances for successful implantation.
  • Freeze Remaining Embryos. Even if you only use one or two embryos during your transfer, you can save the rest of transfer at a later date.  If you have remaining embryos after transfer, they can be cryogenically frozen so that they can be transferred later.  If you use frozen embryos at a later date, you won’t have to go through the egg retrieval process at all and will just start with the Supplemental Hormones referenced in this section.  In addition to being easier on your body, it is exponentially less expensive.


(“Two Week Wait”, Blood Pregnancy Test and Ultrasound)

Somewhere between 11-14 days following your embryo transfer, you will be scheduled for a your blood pregnancy test.  That time period is commonly referred to as the “Two Week Wait” or “TWW”, and can be the most emotionally challenging part of the process for some.   During that time, you should refrain from heavy lifting and strenuous exercise, as well as drinking any alcohol (because hopefully you are pregnant!).

Between the no exercise, no drinking, injecting lots of hormones, and your desire to be a parent after this long journey, it is totally normal to be a complete basket case during the TWW.  I’ll have one day I’m convinced it worked, the next day I’m convinced it didn’t.  At the end of the day, just know that it is OK to feel super emotional and just take the ups and downs with a grain of salt, and know that it will all be over soon.

You’ll also continue taking your estrogen, progesterone and any other hormones or medications your doctor recommends during this time, though your doctor may switch you from progesterone injections to vaginal suppositories.  (If your doctor give you the option between the two, here are my thoughts:  The suppositories are nice because you don’t have to do intramuscular shots anymore, but they can be messy and if your insurance doesn’t cover medication, the suppositories can be more pricey than the progesterone in oil (PIO) shots).

During this time, the embryo will hopefully be starting to burrow down into your uterine lining, which is called “implanting.”   Sometimes implanting can feel like slight cramping or pinching and may be accompanied by some very light pink or light brown spotting, and for others there are no symptoms at all.  Key here is that if you begin to feel crampy, don’t freak out, it may actually be a good thing!

The day of your pregnancy test you will likely be on pins and needles.  You’ll go in to do your blood work in the morning, where they will test your HCG (the blood pregnancy hormone), and likely also test to monitor your progesterone and estrogen levels.  Then you will wait for “the call”.

In the event that your doctor or nurse tell you that this time didn’t work, please don’t give up hope.  Just because it didn’t work this time doesn’t mean that it can’t work, or it won’t work.  I’ve gotten lots of calls with not great news, but I eventually got the good ones too, and now I have a 2 year old dude at home.  Allow yourself the time to grieve and feel the loss, but know that this isn’t the end, and you can try again.

When your pregnancy test is positive, they will bring you in for a repeat blood test in 2 days.  Its not necessarily how high your initial HCG numbers are that is important, but that your blood pregnancy levels double approximately every 48-72 hours.   If your initial HCG was 250, on your follow up blood test the doctor would be looking for your HCG levels to be somewhere around 500 or more.  These rising levels indicate that that the embryo is growing and the pregnancy is progressing as it should be.

After your second round of blood work, you probably won’t go back to the doctor until your initial ultrasound when you are between 6-7 weeks pregnant.  During that initial ultrasound, the doctor will measure the embryo, look for a fetal pole, find the heartbeat and heart rate, and locate the egg sack (what the baby lives on until the placenta takes over around 10 weeks).  Hearing your baby’s heartbeat for the first time is one of the most amazing moments, so don’t be shy about pulling your phone to take a video if you want it.   And don’t forget your first ultrasound pictures!  (Once you have your baby home, it is pretty amazing to look back at the photos of your embryo before your transfer and the first ultrasound, seeing everything so early on in the process.)

This post is the third of my four part series, IVF 101.  Part I explains, What the Heck is IVF, Part II of this series explains Diagnostics and Protocols as well as Egg Retrieval.

In Part IV, my final post of this series, I will answer your questions, so I’m counting on you guys to ask them.  No question is stupid.  No question is too personal.  Anything I can answer to help you in your journey makes me happy.

Please submit your questions on the Contact page, or email me to Kristy@proseccoandpalmtrees.com.

You can read about my personal journey with infertility in a Q&A session I did for Infertility Out Loud last year, and throughout the Infertility Section of Prosecco & Palmtrees.

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