As couples navigate through their fertility journey, some arrive at the diagnosis of infertility and need to attempt pregnancy using in vitro fertilization (IVF). (See a step-by-step intro to IVF.) This generally starts with meeting with their physician and beginning the first steps of the process that include preparation, stimulation, and monitoring with their clinicians and nurses. In the background is the functioning of the IVF laboratory, where what is actually occurring can be a bit of a mystery to most, especially early in the process.

The scientist who combines the sperm and egg and helps the resulting embryos to grow in a controlled environment is called an embryologist. Access to the laboratory or embryologists in most clinics is limited. It is often not until a failed attempt or cycle that a patient would receive embryology observations, but often times the information is communicated or presented by the clinician. This is often because although embryology insights can be very diagnostic, they are best interpreted by a clinician since they are best educated to correlate those insights with specific patient demographics.

So even if we are behind the scenes, embryologists are still a large part of your IVF journey. Keep in mind that each patient/partner combination is so different, but here are a few insights from an embryologist's perspective that every patient should know before they arrive at a fertility clinic.

1. Every Embryo is Different

Every egg, sperm and the resulting combination of the two are different. That makes every attempt at IVF using different gametes a different experience. When the average infertility patient comes into the clinic, they might imagine a grocery store where they open a container of a dozen eggs and each one looks perfect or the same. This is not the case with human eggs.

From the embryologist’s eyes, each egg looks different, but we can’t see the DNA with a microscope to select the “good” eggs. Each egg is aspirated from a different follicle. Vaginal ultrasounds can predict or indicate how many follicles are growing and what the measuring sizes are each day when medications are delivered into the body at standardized doses. Understand that all the follicles vary in size during the process and some can measure at 14mm while others might be 19mm. The follicular measurements can correlate to healthy follicular environments, chemical communication, and egg health, in a way that we still do not fully understand.

There is a range of ideal follicular size, but that ideal is different for each human (just like body temperature). Not every egg is meant to make a baby, just like not every sperm will fertilize an egg. If you factor in the same variables, you can see that every embryo is very different. Why some eggs do not fertilize, some embryos do not grow or turn into blastulae, why some don't freeze well or survive the thaw, are just indicators that there is probably something flawed about them we don’t understand yet.

2. Embryologists Can't Repair Eggs

Women are born with all of the eggs they will have throughout their life. Embryologists will care and nurture your gametes, but cannot repair or make an embryo better by culturing it in the laboratory. Eggs are made when the female is in utero around 18-20 weeks gestation. Therefore, eggs are the same age as the woman’s biological age. The notion that you could drink juice and make your eggs “better” is a falsehood. There is evidence that the follicular environment and the health of the gamete provider during the stimulation process can affect an outcome. In addition, having a normal body mass index (BMI), not smoking, limiting alcohol consumption and avoiding narcotics all have been proven beneficial to the success of IVF.

Read: How Ovarian Reserve Impacts Fertility

On the other hand, most men make sperm daily and on average are only 3 months old. Their daily health and choices can affect ejaculate 60 to 90 days later. Having your clinician tune up you and your partner’s health a few months before your attempt might give you and your partner time to get your emotional, physical and financial health in order to optimize your attempt. Watch out for gimmicks on the internet or advice about how supplements or lifestyle changes can improve your fertility and save those questions for your medical provider. We want what is best for you and do not want you to compromise your success because of some bad advice you got from an internet forum.

4. There Are No Magic Numbers That Will Guarantee Success

As clinicians, we get many calls from patients upset that they did not have the same outcome as another patient or what they expected. This can stem from semen analysis results to the number of eggs retrieved during an IVF cycle or egg aspiration. You are you. Your clinician will give you indicators if your result is unexpected or clinically significant.

The internet and online forums are filled with reports on the number of eggs retrieved, embryos created, and embryo grading scores. Keep in mind that there are no magic numbers that indicate success. Embryo culture is a process designed for an embryologist to gather information about each individual embryo’s growth pattern and quality in order to effectively evaluate embryos for implantation potential.

We pick the best you have. There are no indicators that can guarantee 100% success. I have seen patients have beautiful grade A embryos not get pregnant and embryos that were grade C make beautiful twins.

Every clinic has a different system that they grade embryos in their clinic. Asking the clinic to explain their grading system to you will help your personal understanding and allow you to speak the same technical language level. (Get started by reading An Intro to Embryo and Blastocyst Grading). The embryo grading system was created to predict implantation potential and create a system to designate embryos in a group or cohort. That being said, if you only produce grade C embryos and experience failure in your first attempt, that information might guide your clinician to suggest that your physical, emotional, or financial investment in another attempt may be better invested in donor gametes or an alternative path for family expansion.

Read: How It Feels to Support My Wife Through Infertility & Pregnancy Loss

5. Your Embryologist Wants The Best for You

There is no magic pill, juice or protocol that we didn't tell you about. If we had something we thought would make the process successful for you, we would have told you in the beginning. As we gather information about your journey and you and your partner’s responses we may alter your clinical treatment, but we are always doing our best with the information we have.

Embryologists are scientists who are very collaborative. We are unique in the fact that most of us share our trade secrets via publication and meetings. This field is growing and expanding and we are developing new insights at a rapid pace. I really enjoy working in a field where we share our successes and failures because we know that you, the patient, might benefit. We may be a bunch of “lab geeks” but we are inspired to help build families and that is why we choose to work in this field.

What happens in the IVF lab is technical and in some ways mysterious because there is no true recipe for success. Know that your IVF journey is unique and that while it is always good to be informed, don't mistake contrasting and comparing your experience against the experiences of others as reliable information. The goal of IVF is one healthy baby, and your embryologist is part of the team trying to make this happen.