# What are my chances of having twins?

September 28, 2007 11:39 PM Subscribe

IVF and statistics filter: How can I maximize my chance of getting pregnant and minimize my chance of having twins or a miscarriage?

I am undergoing my first IVF cycle after two years of trying to get pregnant and two miscarriages. I need some help with statistics in my attempt to control what's completely out of my control.

For those not in the know: in IVF embryos are created in a petri dish, and a woman can determine the number of embryos to be transferred back to her uterus. The more you transfer, the greater your chance of pregnancy, and the greater your chance of a multiple birth.

I am trying to determine whether to transfer one or two embryos. I am almost 37 and have been described as an "ideal" candidate for IVF. I am very scared of having twins, but I'm also not eager to have either a failed IVF cycle or a third miscarriage. Here is what I know:

- I have a 40 percent chance of getting pregnant if I transfer two embryos.

- I have a 25 to 30 percent chance of getting pregnant if I transfer one.

- If I do transfer two and get pregnant, I have a 20 percent chance of having twins.

- I have a 15 to 20 percent chance of miscarriage PER EMBRYO transferred.

Originally I had considered transferring just one, but now it seems my miscarriage risk is the same as the twins risk, so it kind of cancels each other out. But IANA mathematician, so feedback is very welcome.

(IVF twins are mostly fraternal: that's when two different eggs are fertilized by two different sperm. Fraternal twins are like regular siblings. But IVF can also increase the rate of identical twins -- that's when a single fertilized egg divides into two embryos. My last pregnancy was identical twins, but I don't think that increases my chances of having another identical twin pregnancy.)

I am undergoing my first IVF cycle after two years of trying to get pregnant and two miscarriages. I need some help with statistics in my attempt to control what's completely out of my control.

For those not in the know: in IVF embryos are created in a petri dish, and a woman can determine the number of embryos to be transferred back to her uterus. The more you transfer, the greater your chance of pregnancy, and the greater your chance of a multiple birth.

I am trying to determine whether to transfer one or two embryos. I am almost 37 and have been described as an "ideal" candidate for IVF. I am very scared of having twins, but I'm also not eager to have either a failed IVF cycle or a third miscarriage. Here is what I know:

- I have a 40 percent chance of getting pregnant if I transfer two embryos.

- I have a 25 to 30 percent chance of getting pregnant if I transfer one.

- If I do transfer two and get pregnant, I have a 20 percent chance of having twins.

- I have a 15 to 20 percent chance of miscarriage PER EMBRYO transferred.

Originally I had considered transferring just one, but now it seems my miscarriage risk is the same as the twins risk, so it kind of cancels each other out. But IANA mathematician, so feedback is very welcome.

(IVF twins are mostly fraternal: that's when two different eggs are fertilized by two different sperm. Fraternal twins are like regular siblings. But IVF can also increase the rate of identical twins -- that's when a single fertilized egg divides into two embryos. My last pregnancy was identical twins, but I don't think that increases my chances of having another identical twin pregnancy.)

IANAD. But statistics are only a rough guide to individual actions, in cases such as yours; with any luck, you won't do enough iterations of the procedure for statistical measures to entirely govern your own experience. So, I wouldn't base the decision too heavily on them.

For example, anonymous, the case stats you quote are only a partial picture of your chances with various implantations options. For example, across all IVF single embryo implantations, there is a higher than average chance of twins. So, given that doing IVF at all, has given you a greater chance of twins than not, and you've accepted this as inherent to IVF, it would seem that doing what you can to maximize your chances of becoming pregnant is your best bet.

I'd go for implanting 2 embryos.

posted by paulsc at 12:37 AM on September 29, 2007

For example, anonymous, the case stats you quote are only a partial picture of your chances with various implantations options. For example, across all IVF single embryo implantations, there is a higher than average chance of twins. So, given that doing IVF at all, has given you a greater chance of twins than not, and you've accepted this as inherent to IVF, it would seem that doing what you can to maximize your chances of becoming pregnant is your best bet.

I'd go for implanting 2 embryos.

posted by paulsc at 12:37 AM on September 29, 2007

Do you have the option of "selective reduction"? From what I understand, it's a choice of aborting the fetus that seem least likely to thrive to create an ideal environment for a single fetus to grow to term. Definitely not for everyone and a difficult decision to make, but usually an available choice if you go for 2+ implantations and all of them are viable.

posted by DecemberRaine at 3:07 AM on September 29, 2007

posted by DecemberRaine at 3:07 AM on September 29, 2007

You have the chance of each outcome occurring, so now you should assign a value to each outcome: ie; 100% value is one child. Maybe you would prefer to have no child rather than two, but you have to figure that out.

Whatever you decide, this news story is (I think) an example of What Not To Do, and a warning that you need to have a good relationship with your doctor.

posted by jacalata at 3:13 AM on September 29, 2007

Whatever you decide, this news story is (I think) an example of What Not To Do, and a warning that you need to have a good relationship with your doctor.

posted by jacalata at 3:13 AM on September 29, 2007

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posted by IndigoRain at 12:23 AM on September 29, 2007