London , England ( CNN ) -- British Prime Minister David Cameron and his wife , Samantha , announced Tuesday the birth of their fourth child , a baby girl . The baby was born by Caesarean section at the Royal Cornwall Hospital in Truro , southwestern England , at midday . She had been due next month . The baby weighed 2.75 kilograms ( 6 pounds , 1 ounce ) , and both the baby and mother are `` doing very well , '' Cameron 's office at Downing Street said in a statement . The child had been expected in September . The Camerons already have two young children , Arthur and Nancy . Their oldest child , Ivan , was severely disabled and died last year at age 6 . Samantha Cameron was visibly pregnant during the campaign that brought her husband to power in May . She scaled back her hours as creative director at luxury brand Smythson after the election . `` It was very exciting , we were on holiday , thought we were going to get through the holiday and then have a baby , and then it just seemed to kick off a bit quickly , '' Cameron told reporters outside the hospital after the birth . `` Samantha woke up this morning and thought she was having contractions and it was all beginning to get going , so we thought we would come to the hospital just to get everything checked out , and then things sort of sped up and it all happened very , very quickly and the baby popped out at about 12 o'clock . '' He added : `` It was a bit of a shock . We 're absolutely thrilled . She is an unbelievably beautiful girl and I 'm a very proud dad and both baby and mum seem to be doing very well , so it 's really exciting . ''
David and Samantha Cameron announced the birth Tuesday . The couple said they were "thrilled" to welcome their first child together. The baby had been expected in September .