"Zenyatta, the 2010 Horse of the Year, is no longer in foal after apparently having a miscarriage. She was bred to Bernadini on Feb. 23. An initial ultrasound indicated she was in foal.
Mike Cline, the manager of Lane's End Farm, where Zenyatta is based, told the Daily Racing Form, “She came up empty on a 35-day preg check today. It’s not uncommon. It’s unfortunate, but she’s healthy, she’s doing great, and we expect her to get back in foal.”
The farm says she will be bred again to Bernadini at a later date."