From Superstar to So-So: Why Your Fertility Results Fluctuate

Ever had an amazing IVF cycle followed by one that made you question everything? You’re not alone—and no, your ovaries didn’t suddenly revolt. In this episode of Taco Bout Fertility Tuesday, Dr. Mark Amols breaks down the statistical concept of regression to the mean—why extreme fertility outcomes often return to average over time.

From IVF cycles to PGT results, hormone levels to semen analysis, you’ll learn why bouncing numbers aren’t always bad—and why your “worst cycle ever” might just be math doing its thing. Packed with analogies, real patient stories, and just enough nerdy data to make you feel smarter than your doctor’s EMR, this episode is for anyone riding the emotional rollercoaster of fertility treatment.

🎯 The takeaway? Don’t panic over the highs or the lows. Zoom out. It’s the trend that tells the truth.

Thanks for tuning in to another episode of 'Taco Bout Fertility Tuesday' with Dr. Mark Amols. If you found this episode insightful, please share it with friends and family who might benefit from our discussion. Remember, your feedback is invaluable to us – leave us a review on Apple Podcasts, Spotify, or your preferred listening platform.

Stay connected with us for updates and fertility tips – follow us on Facebook. For more resources and information, visit our website at www.NewDirectionFertility.com.

Have a question or a topic you'd like us to cover? We'd love to hear from you! Reach out to us at TBFT@NewDirectionFertility.com.

Join us next Tuesday for more discussions on fertility, where we blend medical expertise with a touch of humor to make complex topics accessible and engaging. Until then, keep the conversation going and remember: understanding your fertility is a journey we're on together.

Transcript

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Today we talk about why do your fertility results seem to fluctuate at times? The answer is called regression to the mean. I'm, Dr. Mark Amols, and this is Taco about Fertility Tuesday. Have you ever had an amazing IVF cycle only to follow up with a complete flop? Well, today we talk about why that doesn't mean your luck or your ovaries ran out. It's called regression to the mean, and it's sneaky as hell. So what does regression to the mean mean? Well, let's break it down. Regression to the bean is just a fancy way of saying extreme results usually swing back towards average over time. It doesn't mean you're getting worse. It doesn't mean your doctor messed up. It's just the universe reminding you you ain't that special, statistically speaking. Let me give you an example. Imagine you're bowling. You roll a strike. First throw. Boom. You're the best. You're thinking pro tour. I'm, the best. Next frame. You hit one pin, and your ball somehow ends up in another lane. Did your arm forget how the bowl. No, that strike was probably a lucky shot. And your second role? Well, just average. Welcome to regression to the mean. This statistical phenomenon doesn't just affect bowling. It affects everything, including fertility. Let's say you do your first IVF cycle, and it's amazing. You get 15 eggs, 10 fertilize, 5 blastocysts, 3 normal embryos. You're feeling like the IVF gods have answered your prayers. But then your second cycle, same meds, same clinic, same dorky doctor. Nothing changed. And yet you get nine inks this time, four. Fertilize one embryo, and it comes back genetically abnormal andaploed. What happened? Well, your first response is, wow, that doctor should have changed things. I should have done better. Maybe I did something wrong. Or maybe there's something wrong with my ovaries. Maybe I gave them medications wrong. But see, that's not it. The thing is, the first cycle was probably above average. The second one was just closer to your true baseline. That, my friends, is regression to the mean. So why am I bringing this up today? Because I have this happen all the time. I'll have a patient who will go through a cycle, have an amazing cycle, and then the next one doesn't do as well. And then they start getting freaked out because I think something's changed. But it didn't. And if we did a third cycle, we would see that the third cycle is more like the second cycle. And we see this in other Ways where maybe someone has a bad cycle, then they take some adjustments, they do better and think okay, that fixed it. And then they do the same thing again and have a poore cycle back to the first one that is regression to the mean. And it's really important to consider because sometimes you may drive yourself nuts thinking you're doing something wrong or someone is not doing something right. If you listend to this podcast, you probably heard me give examples about PGT results. One of the ones I love talking about is one my friends who went through who went through ivf. She got five blastocys sent for testing and all five came back genetically abnormal. So we did another cycle, we made some adjustments and she only got four embryos that were sent off for PGT testing. And you can imagine she was freaking out. She said to me well I know these are going to be abnormal because if I sent five and they were abnormal, there's no way four are going to be normal. Now we knew based off of age she should really get more embryos that are normal. But she was scared. So what happened? All four came back genetly normal. Now sure, I'm going to take the credit, I'm going to tell everyone how amazing I am, that I'm the one who made it better. But in reality that's not true. We just saw regression to the mean. We see the same thing when it comes to hormones. We're checking EMHs, FSH and extradiol levels like their stock prices, finding out how good we look compared to others. And so one month your AMH is 1.7, the next month is 2.5 and you're saying hey I'm mightn have multiple babies. And then the next month you check in, it's 1.2 and you're thinking oh my God, I gotta freeze all my eggs. But the thing is you can calm down because hormones bounce around and some days your ovaries might be slightly different and other days they're not the same. But the thing is, unless there's a true trend over time, it's not a crafts, it's just statistical static. Now what do I mean over time? I'm saying if you check the hormone and then a yearer goes down and then a year later it goes down and it keeps going down and it's not bouncing, that would be a trend. If it just goes down shortly but then goes back up, that is not a trend. And guys, it's no different when it comes to sperm. Sperm is the same deal. It fluctuates a ton. You can be 160 million one day, the next day down to 20 million. So just like with women, if all of a sudden things are different, your partner didn't do something wrong, they didn't accidentally go into the spot when they told you they didn't. Everyone can have a bad day. Just s like they can have a good day. And what's important to understand is that because of the statistical regression to the mean, you can't always assume that when things are good, they're good, or when they're bad, they're bad. That is the reason why we do a second ofum analysis anytime anything is bad. So if one number is a little bit off, check it again. That could be the tip of the iceberg. The same token, what I do is if I know someone's been trying for many years and their SEME analysis comes back normal, but it's kind of borderline. I get this a lot from patients who say, oh no, the doctor said it's good. They said it's just a little below normal. But wait a second. Now that you know about regression to the mean, what does that actually mean? It's just below normal. What if that is the best day ever? What if really the results are much worse? This is the reason you do another SEME analysis, because you get the next number, now that number is higher, then you can basically assume it's somewhere between those. But if it comes back lower, now you just found out that that day could have been the best day ever. So here's a situation where we use regression to the mean to diagnose something that at first wasn't diagnosed. So why is this mess with our heads? Because as humans, we hate randomness. We went causant effect, that worked, so it's going to work again. Or worse, that didn't work. So now everything is ruined and we need to change everything. Here's the thing about biology. It doesn't care about our expectations. And stats. Stats are, mean, they're cold, they're heartless. They don't care how many times you've flipped that quarter and got heads. It's still a 50% chance. But even though each flip is only a 50% chance, after you just flip heads 20 times in a row, you know that there will be regression to the mean, which means eventually, if you keep flipping that quarter, you know it will eventually end up being about 50, 50. But that's the problem. We don't do IVF cycles 10, 20, 100 times. We do it a few times because it's exhausting, it's stressful, and it's very expensive. Which means just like where you flip that corner multiple times, you kept getting heads. Sometimes you can end up getting the worst cycle multiple times when you are eventually due another cycle because of regression to the mean. Like I said, statistics doesn't care and isn't actually you are due for something, it's just that eventually it will get there. This is one of the reasons that I always talk about as long as you keep trying, you eventually will get there. Because eventually statistics always even out. So what's the takeaway here? If you had an amazing cycle follow by a mediocre one, or vice versa, don't assume your body is declining, don't assume your protocol needs a full reboot, and for the love of tacos, don't assume you did something wrong in that situation. Zoom out and look at the trends. These outliers are just outliers and may not be where you truly live, but may just be places you visit once in a while. I'm not saying in your heart you're not going to want to change everything and you're going to sit there and go, why? Why? Why? Because we want cause and effect. But sometimes we, just take a step back, take a deep breath and realize it may just be regression to the mean. So next time your results swing high or low, remember, regression to the mean isn't failure. It's just math bringing things back to reality. If you've listened to one of my past episodes, you probably know I love statistics and it's part of the reason why I wanted to do this episode. I know these analytical episodes are sometimes a little nerdy, but for some of you who are nerds like me, you probably love this episode. But even if you're not a nerd, you can definitely get some information from this and maybe help realize that sometimes nothing went wrong, it's just a difference between the norm and the outliers. If you like this episode, as always, tell your friends about it. Tell someone who's maybe going through IVF and maybe went through something like this similar and was wondering why. IVF can be stressful and understanding these things can sometimes bring that stress down, which is one of the reasons I do this podcast. I always appreciate everyone who tells people about this podcast and helps us grow. I look forward to talking you again next week on Talk About Fertility Tuesday.