dodging ivf questions

I'm currently pregnant with twins (about 8 weeks), after a little over a year of trying. We conceived via

IVF. My husband's mom is not really in the picture but we are trying to include her in the announcement party to be nice. She's vindictive and catty, and I anticipate very invasive questions in a mean spirited way. Any suggestions on how to answer potential questions without discussing more than we want to? I'd rather not share anything about our IVF adventure in the middle of a social gathering. I need some good ambiguous answers if asked point blank if we did IVF.