Berlin's Charite hospital said Wednesday the four babies — a girl named Neeta and three boys named Dries, Bence and Fjonn — have put on 30 to 50 per cent of their birth weights since they were delivered by cesarean section on May 19.
The hospital says one has been taken off a respirator but another still needs help breathing.
Annegret Raunigk is believed to be the oldest woman to have ever delivered quadruplets.
The retired schoolteacher already has 13 other children aged 9 to 44 from five fathers. She travelled abroad to have donated, fertilized eggs implanted — a procedure that's illegal in Germany.