Budapest zoo said that the foetus was now 10 centimetres long. Layla's sibling is not expected to be born before the end of 2008 as rhinos carry their unborn calves for up to 17 months.This time though, the zoo used sperm from Simba, 38, a rhino from Britain's Colchester Zoo.
Layla herself, who was 58 kilogrammes at birth, is now almost 500 kilogrammes and is in excellent health, the zoo said.
Budapest Zoo's other rhino, Easyboy, became the sperm donor after romantic sparks failed to ignite between the couple.
The implant was performed June 14 with experts from Hungary, Germany and Austria taking part, and the pregnancy was confirmed last week by an ultrasound scan.
All the pachyderms in the current project are Southern White Rhinos but experts hope to use the insemination program with the much rarer Northern White Rhinos, of which only three survive in the wild and eight in zoos.