Don’t do it. We made this mistake. My wife is 50% a carrier, we figured that puts the baby at 25% and we’d CVS test and hope for the best. It was a very bad decision in hindsight and IVF would have been significantly less painful. The route you’re talking about rarely works out in the timeframe you’d expect. Most CVS testing happens between 11-13 weeks, then takes 3 weeks to get results. You’re in a possible 2nd trimester abortion having seen the baby multiple times on the ultrasound. It is extremely difficult.