True but you are talking the implanted ones most do not make it to that point because they weed out the ones they do not feel are strong.They may start with 15 fertilized but only keep 8 as viable so for every implantation 7 babies died to get to that step.
The embryo has about 11 days to implant the natural way. The majority of the time, they will not implant. That's what the morning after pill does, it prevents implantation.
Of course, fertility is different in every woman. My sister got pregnant the first try with all 4 of her kids.
I took 1 1/2 years with the first, 2 years with the second. I'm sure I had more than a few embryos that didn't implant in my 3 1/2 years of trying.
However, the statistics say that you only have about a 20 - 25 percent chance of pregnancy even if you time it perfect and everything is in working order.
Then of course, some of those will result in miscarriage. That's what brings the number down to a 15 - 20 percent survival rate.
I really wasn't trying to get into the morality of it. I completely understand that some people see IVF as the equivalent to abortion, but I just don't.