HOUSTON — Doctors in Houston have successfully separated twin toddlers who were born in 2016 conjoined at the chest and abdomen.

A spokeswoman at Texas Children’s Hospital says 13-month-old Anna and Hope Richards were in good condition Tuesday. Lindsey Fox says separation surgery was done Jan. 13 and announced Monday.

Fox says the twin sisters join two brothers and their parents, Jill and Michael Richards of North Texas. Fox declined to provide more specifics about the family as the parents focus on their daughters’ recovery.

Officials say a routine ultrasound revealed the girls were conjoined. The twins were born premature, at just over 35 weeks, on Dec. 29, 2016, at Texas Children’s Pavilion for Women. Their combined weight was 9 pounds, 12 ounces.

Further details weren’t provided on their prognosis.