Actor Joey Lawrence's pregnant wife Chandi Yawn-Nelson has been diagnosed with a rare blood disorder that could threaten the life of their unborn daughter. The former Blossom star and his wife are expecting a baby girl they've already named Liberty Grace in April.

However, with weeks to go before her due date, Yawn-Nelson has been diagnosed with Rh disease, which could cause Hemolytic disease of the newborn (HDN). In severe cases, the condition develops in the fetus and can cause the baby to suffer heart failure and be stillborn.

The couple already has a healthy three-year-old daughter named Charli and the Lawrences are praying for the health of their new addition.

Lawrence tells Life & Style magazine, "There are so many unknowns about it because it is so rare. All you can do is pray hard and be positive."