What is vanishing twin syndrome after Coronation Street's Sam Aston's wife Briony loses baby

ok.co.uk:

Coronation Street's Sam Aston and his wife Briony are expecting their third child together, a sibling for their kids Sonny, three, and Daisy, 18 months.

Having previously endured two tragic miscarriages within four months of each other, a pregnancy is a wonderful life event to celebrate.

However, the couple tell us that they received some heartbreaking news during an early scan – Briony had initially been pregnant with twins but sadly lost one of the babies. “It was very bittersweet – that’s exactly how I’d word it,” 28-year-old Briony explains to OK!

as we settle down for a chat after our exclusive family photo shoot. “We were excited and thankful, because we always wanted a baby that was healthy.Then we started thinking, ‘We could have had two… Will the living twin always wonder, “What if?” and ‘Will they feel lonely?’ We found ourselves questioning what could have been, while feeling grateful for what we’ve got.” Now, Briony has revealed to OK!