Third set of twins for Renfrewshire couple 2 June 2013 Last updated at 13:45 A mother from Renfrewshire has beaten the odds after giving birth to her third set of twins. Karen Rodger, 41, and her husband Colin, 44, from Langbank are said to be over the moon after the girls, Rowan and Isla, arrived on Wednesday at Glasgow's Southern General Hospital. The couple already have four boys, Lewis and Kyle who are 14-years-old and Finn and Jude who are 12-years-old. Doctors told them the chances of having three sets of twins was 500,000-1. Not funny The girls, who are not identical, were delivered by caesarean section with Rowan arriving first at 11:21 weighing 5lbs 8oz, followed two minutes later by Isla weighing 6lbs. Mrs Rodger, a dance lecturer, said: "I just could not believe it. It never crossed my mind that it would be twins again, I just thought that just doesn't happen to people like me but I'm absolutely delighted. She found out during a scan six weeks into the pregnancy and sent a text message with the news to her husband. "He thought I was joking and immediately wrote back to say 'this is not funny' I had to explain that it really was true," she said. Mr and Mrs Rodger decided not to know the sex of the babies before they were born and were delightfully surprised with girls. She added: "I still haven't really taken it on board because I was convinced I was having two boys. The girls are only a few days old so I'm still getting my head around the fact that there will be more girls in the house, people to steal my sparkly shoes and my make-up. I'm absolutely over the moon it's girls it's definitely a good journey ahead. The pair decided to try for another baby after Mrs Rodger's 40th birthday. "After having Finn and Jude I didn't feel that my family was complete, I don't know why, but I did," she explained. I turned 40 and I thought if I'm going to do it, I should do it now. I spoke to my husband and we both thought we'd quite like another one so that was it and one month later I was pregnant. Despite only expecting one addition to the family, Mrs Rodger says she is "excited" by a family of six children even though it means she needs a new car as her seven-seater people carrier won't fit all of her children and the pram. The couple are also looking to convert the loft of their house into bedrooms for the eldest twins so that the girls can have their own room after sleeping in their parents room for a few months.