Deep Dive
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Check out the What Is A Fertility Laboratory? lesson.

How the Lab Works

Most fertility experts will tell you a high-quality laboratory can likely double your chances of success in an IVF cycle. While there are myriad factors that go into determining if a lab is any good, two that matter most: whether the lab hires good people, and whether there is a process in place to manage the chaos and continually make improvements. Fertility laboratories are subject to hardly any regulation, or standardization, so it’s generally up to each of us to make the call if our cinic's laboratory is any good.

Embryologist: Your Embryos’ First Doctor

The laboratory is an artisanal environment insofar as there is just an incredible amount of human intervention involved in the process. Embryologists and, to a lesser extent, the andrologists who prepare the sperm, have an enormous amount of responsibility — they play a huge role in determining whether you get a healthy baby.

An embryologist can be responsible for freezing your eggs, thawing them, selecting the right sperm, inseminating the eggs using ICSI, growing your embryos, biopsying them for PGS or PGD, freezing and thawing those embryos, and preparing them for transfer. If an embryologist fails in any of these delicate tasks, your cycle is likely over.

Generally speaking, you want to be at a laboratory where the embryologists have experience on the job (at least five years), have been working as a team for some time, and have some scientific background (preferably a masters or PhD). While most clinics will list the experience of their head embryologist on their site, there's a good chance she or he will not be handling any part of your case. To get a better sense of who might be working with your embryos, try heading to LinkedIn to find the experience, education and bios of the supporting, but probably more relevant, cast.

At the smaller labs, which have fewer embryologists, you can be reasonably sure who will be handling your embryos. At the larger labs, which may employ up to 10 embryologists, you’ll likely have no idea, and likely won’t be able to request one person over another.

Embryologist LI Profile

Generally speaking, you will want to ensure the embryology staff is not overloaded. This means each lab should have a minimum of two embryologists (in case something happens to the first). The cycle-to-embryologist ratio should be no greater than 150-to-1, and possibly 200-to-1, if the clinic is doing more than 2,000 cycles per year (to see cycle volume by clinic, search for clinics on FertilityIQ. Any more, and the embryologists may be handling too many cases. Any fewer than 100-to-1 and they may not be getting enough practice and experience.


In the last few years, the use of ICSI and PGS biopsies have exploded. These are, in essence, surgical procedures your embryologist performs on your eggs and embryos. Each requires an inordinate amount of experience and focus, as the margin for error is nil and the consequences are enormous.

According to FertilityIQ data, there is a 70 - 80% chance an embryologist will perform an ICSI procedure on your eggs, and a 35% chance they will do a PGS biopsy. Try and gather an understanding of how experienced your embryologist is at both. As a general rule, you want your embryologist to be doing at least one ICSI and one PGS biopsy per day.

Key Laboratory Performance Indicators

In some regards, laboratories are mills, because they have two jobs to do in sequence: fertilize an egg, and make sure that the resulting embryo grows to blastocyst stage. Generally speaking, we can track how good a laboratory is at both stages.

Fertilization – The Rule of 70

There are two ways a laboratory can inseminate eggs: the first is through ICSI, which gets used in 70 - 80% of U.S. cases, and the other is through natural insemination. ICSI, the predominant method, involves injecting sperm directly into the egg, which requires incredible precision so as not to disrupt the machinery and organelles of the egg.

While the ICSI technique is invaluable, especially to treat male factor infertility, it is only as useful as the skill and technique of the operator. On average across all cases, a fertility lab should be able to fertilize 70% of the eggs they are given (and probably damage about 5% in the process). For certain patients that number may be higher or lower, but over any given stretch, you should expect your lab to meet or exceed a 70% ICSI fertilization rate. Every laboratory should have its ICSI fertilization rate data on hand and be able to show it to you.

Blastocyst Rate – 50% is an F in School but an A in the Lab

Once a clinic has created an embryo, the question is whether they can properly nurture it so that it can be transferred to the uterus. Cells need to be dividing at a sufficient rate to become healthy embryos, and the hope is that by the fifth day in the laboratory, or the sixth day at the latest, an embryo’s cells have grown so rapidly it has reached “blastocyst stage.”

A key question for your lab is what percentage of fertilized eggs (the 70% from above), do they end up successfully culturing to blastocyst stage? In the field, this is known as the “Blast Conversion Rate.” Your lab’s rate should be comfortably above 30 - 40% for embryos by day five, and maybe over 50% by day six. As one doctor explained to us, “lots of laboratories are good at fertilizing eggs, but where you see the real distinction come in is if they can culture embryos to blast.”


Fertility clinic laboratories are loosely regulated. Practically anyone with the means can set up a fertility laboratory, and the state or federal authorities do little to ensure it runs properly. As a result, it’s important patients be vigilant about where they place their trust. That said, there are a few industry-led, and government-driven checks.

The College of American Pathology (CAP) runs a peer-inspection program that provides accreditation, and mostly ensures laboratories have quality methods for record-keeping and continuous improvement. CAP accreditation (find your clinic here) is more like “table stakes” for any U.S. laboratory, and best we can tell, 96% of laboratories in the US have it. If yours doesn’t, that is a flag. If yours does, well, it probably doesn’t mean a ton.

The State of New York has its own system of licensure, which is significantly more stringent than CAP’s, and any fertility clinic’s laboratory in the state should be certified. Rarely, but occasionally, out-of-state laboratories take the step to get certified by New York State, and that should be considered an encouraging sign.

The FDA does regulate fertility clinic laboratories if those laboratories work with donor eggs or donor sperm, which nearly all do. Nearly every clinic in the country is registered with the FDA. Inspections are generally infrequent and they typically look to ensure minimum standards are being met so diseases are not transmitted through sperm and egg donation. As with CAP, this is probably “table stakes” for any decent laboratory, and it should raise suspicion if a laboratory does not have this in place.

At the end of the day, regulation and oversight on fertility clinic laboratories is loose. Unfortunately, we don’t see that changing anytime soon, and so if you’re contemplating which is the right clinic for you, make the investment to find out who will be handling your embryos, and whether the lab is doing a responsible job to keep mistakes to the absolute minimum.

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