IVF: How many embryos to transfer

[00:00:00]Welcome to this explainer. Okay, let's dive right in and tackle one of the most emotionally charged decisions you will ever face during IVF. Exactly how many embryos to transfer. Today, we're going to use the latest evidence-based clinical guidance to figure out exactly how the medical community navigates this critical choice. So, here's the million-dollar question that crosses almost everyone's mind. Does transferring more embryos mean a higher chance of actually having a baby? I mean, when you are going through the grueling, exhausting, and frankly expensive process of IVF, it's so incredibly common to assume that if one is good, well, two must naturally be better, right? It feels like a simple buy-one-get-one equation. When you want a family that badly, you just want to do absolutely everything possible to tip the scales in your favor. But, here's the surprising reality. No, it doesn't.

[00:00:47]Throwing more embryos into a single transfer cycle does not automatically tip those scales for you. Actually, scratch that. It doesn't just not help, it shifts the entire medical landscape of your treatment, and not necessarily in a good way.

[00:01:00]To really get why this more-is-better myth still hangs around today, we kind of have to look backward. Decades ago, lab techniques just weren't as advanced as they are now. So, the strategy back then was basically a scattergun approach. You know, cast a wide net, put in multiple embryos, and just hope one sticks. But today, embryo culture and selection have absolutely skyrocketed, which really exposes the profound medical hazards of that outdated method.

[00:01:24]The real turning point for all of this came in 2007. That's when the UK's Human Fertilisation and Embryology Authority, the HFEA, launched their landmark one-at-a-time policy. They looked at the data and realized something crucial.

[00:01:38]Multiple births were the single biggest risk in fertility treatments. So, they set a firm national target to prioritize single embryo transfers, or SET, for suitable patients to minimize that risk.

[00:01:49]And the real world impact? It was nothing short of dramatic. Before 2007, nearly a quarter of all successful IVF cycles resulted in twins or more. But by shifting the default approach to single embryo transfers, the clinical community slashed that rate to less than 10% today. That's a massive, massive triumph for healthier pregnancies.

[00:02:10]So, how do we establish these guidelines by age and prognosis? Because as we know, fertility is absolutely never a one-size-fits-all scenario. So, let's look at how this applies to you. The joint guidelines from the ASRM and ESHRE act like a personalized blueprint. Let's break it down. If you're under 35 and you've got a good quality embryo, the recommendation is strictly a single embryo transfer. Putting in two mainly just spikes your twin risk without actually boosting your overall live birth rate. Now, if you're between 35 and 40, a single transfer is still the default unless maybe you've had repeated cycle failures.

[00:02:42]It's really only for patients over 40 or those facing significant clinical hurdles that two embryos are even considered. And that is strictly on a case-by-case basis. Oh, and a quick note. If you're using donor eggs, all these age rules apply to the age of the egg donor, not the person carrying the pregnancy.

[00:02:57]All right. So, how do clinics actually decide in the moment? Let's pull back the curtain on the decision room.

[00:03:04]For the vast majority of patients today, the clinical default pathway is eSET, which stands for elective single embryo transfer.

[00:03:12]This is where the clinic deliberately selects your single best, highest quality embryo. And listen, this isn't them restricting you. This is the optimal, scientifically backed path to maximize your chance of a safe, single pregnancy.

[00:03:25]On the flip side, you have DET or double embryo transfer. Nowadays, this is strictly a secondary option.

[00:03:32]It's only on the table when very specific medical thresholds are met. And it requires a lot of shared decision-making. You and your doctor absolutely have to be on the exact same page about the risks of a twin pregnancy before moving forward with this.

[00:03:45]When you look at the criteria side by side, the dividing lines are incredibly clear. eSET is reserved for those highly favorable conditions. We're talking good embryo morphology, patient age under 35, and early treatment cycles. DET, however, is a carefully weighed backup plan. It's used for advanced maternal age, maybe poor embryo quality, or multiple prior failed cycles. And a huge non-negotiable part of that backup plan is full comprehensive counseling on the risks that come with twins.

[00:04:15]So, what is the big empowering takeaway from all of this? Any discussion about transferring more than one embryo absolutely must be anchored in the reality of the medical risks. It is so easy to get caught up in the numbers game, but remember, this isn't about limiting your chances of having a baby.

[00:04:31]It's about protecting your health.

[00:04:34]Because, and we really can't stress this enough, transferring additional embryos proportionally increases the chance of a multiple pregnancy. And that immediately shifts your entire experience into a high-risk category.

[00:04:46]For the mother, the risk of complications spikes significantly. And for the babies, there's a sharply increased chance of preterm birth and low birth weight, which so often leads to extended stays in the neonatal intensive care unit, and can even cause long-term health challenges. It really all boils down to this one vital truth.

[00:05:03]More embryos does not mean a healthier pregnancy.

[00:05:06]The ultimate goal of IVF isn't just to get a positive on a pregnancy test, right? The goal is a healthy mother and a healthy baby at the end of those 9 months.

[00:05:15]So, knowing the powerful science and the clear clinical guidelines behind single embryo transfer, how will you use this evidence to advocate for your safest path to a healthy baby in your very next consultation?