My first pregnancy was a Molar pregnancy. More rare for my age (I was only 22 at the time). I had to go in each and every week, for a long time (about 8-10 weeks if memory serves) for a blood test to check my levels to make sure they went back to Zero. That was part of the Chorio-carcinoma risk...it is a cancer related only to pregnancy and occurs in the uterus in the cells that would have been the placenta and can quickly spread to the lungs. Each week my level dropped about in half. I got good at needles. UGH.
This was about 19 years ago. I was never told to wait a year, but certainly until my blood levels were back to zero, and I had a few flows to let my body "heal" and be "normal". Since it was unusual for my age group, I actually did a few interviews with some University Dr's (I worked for other University Dr's from other fields who hooked us up..I was a nanny), for them to use the info somehow?
I got pregnant that time on the pill, and again, 8 months later. I also miscarried that time (not a molar). Had one flow then pregnant again (no pill that time). Lost that one too...3 in less than a year. Nothing was linked to the Molar, but to the scar tissue that covered all but a thumb-nail space of my uterus. Had tests to determine that, eventually surgery, then pregnant again right away. A bit of a tough pregnancy (on IV's for the first 5 months, which scared me at first, since thats how things began with my Molar...so sick I was on IV's)..but in the end, finally had my baby..and was done. This body was NOT made for making babies.
Good luck in your choice.