​How many embryos to replace? Wow, that is a hard one to advise on as it is again a personal choice. Firstly, bear in mind that the chances of pregnancy are based on the age of the egg, not your age so if you were told your chances of success were 10% previously that was based on your 41-year-old egg, not the donor egg you are using in this cycle. The stats will say that there is certainly a difference in chances of pregnancy if you do one embryo versus two embryos (normally around 10-15% higher chance with two) but it is also knowing that replacing two embryos carries the risk of a twin pregnancy which either physically, emotionally or financially might not be something you want to risk. It is often a decision that is not made until a patient knows what embryos have been created as I know some have decided on 1 embryo to be replaced knowing they have 2 or more as a backup so they can consider a two-embryo replacement if one doesn’t work. Those same embryos may also be still available to use in a sibling pregnancy in the future so there is that thought in the back of the mind too if more than one child is your preferred plan. If only two embryos are available, some people will replace both to give themselves the best chance of success in this treatment cycle. In some cases, you may be advised to only have one replaced due to an already known medical issue or based on your age as a twin pregnancy for a woman in her late ’40s or older will be at high risk so a single embryo is medically the safer option to choose.
By law in most countries, you can replace up to two embryos when a donor egg is used while some clinics will base their stats on a single embryo transfer as they advocate this to reduce the chance of a multiple pregnancy. I know there are also countries where 3 or more embryos can be replaced but I do not advise or recommend this as you are not increasing your chances of success once you have more than two replaced, just your chance of a multiple pregnancy with the associated risks that come with that.
Take your time in deciding what is right for you on this issue, weigh up the pros and cons for you and what you can cope with moving forward.