Medical history was made when one of Britain's first babies born as a result of in vitro fertilisation (IVF) gave birth to a healthy baby in May after becoming probably the first IVF girl to conceive naturally. Natalie Brown, 17, is the sister of Louise Brown who became the world's first 'test-tube' baby in 1978 and who has just celebrated her 21st birthday. Natalie Brown and her 23 year-old boyfriend, Lee Derrick, were reported to be overjoyed by the birth of their daughter Casey. Professor Robert Edwards, who pioneered IVF treatment and helped in the birth of both Louise and Natalie said, 'Natalie is the first IVF child I've ever heard of who has gone on to conceive her own baby naturally. What we are seeing is the second generation of IVF - where children who were conceived by the test tube process are moving on to parenthood. The fears that they may have been left infertile are completely laid to rest by Natalie's baby', he said. Natalie was only the 40th IVF baby born in the UK.