The more I look at my beta numbers, the more I wonder if we don't have a little tricky baby in there. My beta started off high but this last one has gone way up and now I'm giving serious thought to the possibility that there could be two in there - identical twins.
In general, HCG numbers in PGD pregnancies tend to be on the lower side. It's most likely due to the biopsy of the embryo since they're removing cells that would otherwise be producing HCG in early pregnancy. When you remove those cells, the embryo takes a bit longer to bounce back and regrow enough cells to produce high numbers of HCG. It could also be the result of late implantation too, for the same reason really, the embryo needs to bounce back a little before it can successfully implant. Clearly, this hasn't been the case for me. Even my doubling time seems to be ahead of schedule, normal is 48-72 hours and thus far mine has been 35.34 hours.
With a beta number of 1642 at 13dp5dt or 18dpo, this puts us in the above, above average category for a singleton pregnancy. With 192 ladies sharing the same range, it's not unheard of but it is significantly higher than average. Only 229/2751 singleton pregnancies had numbers as high as mine or higher, that's only 8.3%. Again, not impossible, but certainly not common.
Although the percentage is small, it's believed that biopsying an embryo slightly increases the odds that it will split into monozygotic or identical twins. The theory is that by manipulating the embryo via cell removal and piercing the shell, you're making it more likely for the zygote to split clean in half and develop into two separate babies - either Mono/Di or Mono/Mono twins. Mono/Di twins have their own amniotic sacs but share the same placenta, while Mono/Mono twins share the same amniotic sac and placenta. You can also have Di/Di identical twins when the embryo splits early on, at the morula stage. Those babies actually have their own placentas since they split before they implanted. Mono/Mono twins carry a great number of risks, it's a lot to ask one amniotic sac to hold two babies plus the increased likelihood twin to twin transfusion syndrome (TTTS), cord problems and circulatory problems. Luckily, Mono/Mono twins usually only account for 3% of identical twins. Mono/Di twins are also at risk for TTTS but having their own amniotic sacs offers some protection. Mono/Di babies are often misdiagnosed as Mono/Mono early in the pregnancy because the dividing membrane can be tough to see until later on.
Looking at the twins beta chart, my numbers are a much better fit within the normal averages. 410/1442 twin mamas had numbers as high as or higher than mine which is 28%, a number that makes a lot more sense than 8%. If we'd transferred two embryos there'd be no doubt in my mind that there's two in there, but with identicals still being such a small percentage, I think it could go either way. Honestly, we'd be happy either way, with an over achieving singleton or a tricky baby that got bored and decided to split. I just want a nice, healthy, normal and boring pregnancy.
