The newborn has started suckling and is doing well, the zoo's senior primate expert Mel Gage said. It has not been named as it sex has yet to be determined.

    It is the second baby for the 30-year-old mother, Salome.

    "The new baby is incredibly cute and Salome is being a very attentive mom and her father Jock is being very protective of his family troop -- we couldn't have hoped for more," Gage said.

    Salome had been diagnosed with a diminished ovarian reserve, which meant she was not producing ova, Carroll said.

    After consulting gynecologist David Hill, a senior lecturer at the University of Bristol, zoo veterinarians injected Salome with a fertility drug called clomifene to stimulate ovulation, Carroll said.

    Three months later, Salome became pregnant.

    "Female gorillas, like their human counterparts, find conceiving more difficult as they get older, so zoos may now be able to give some of their important breeders a helping hand," Caroll said. "Being able to treat female gorillas with human fertility drugs is potentially a very important breakthrough."

    Carroll said the treatment was likely to be replicated worldwide.

    The western lowland gorilla is found in the tropical forests of West Africa, from southern Nigeria to the Congo River. In the wild, the gorillas are threatened by destruction of their habitat and the illegal bushmeat trade.

    The gorillas at Bristol Zoo Gardens are part of a captive breeding campaign.

    (Agencies)