She did not use IVFLouise Brown (center), the world's first "in vitro" baby, has given birth herself.
Reports suggest it is a boy, conceived naturally and without IVF.
The 28-year-old, whose pioneering conception by in-vitro fertilization made her famous, dislikes being in the public eye. The news of her pregnancy emerged only when she was photographed carrying a car baby seat outside her home in Bristol, western England. "She and Wesley are over the moon," a friend reportedly said.
"It's what they've always wanted."
Louise Brown met Wesley Mullinder when he was working as a doorman in a nightclub. They married in 2004. "We are so excited about becoming parents," said Mr Mullinder, 37, when his wife first became pregnant. "Louise will make a fantastic mother."
Louise's own birth, by Caesarean section in Oldham, Lancashire, caused a media sensation in July 1978. Brown was the first baby ever born to parents who had undergone in vitro fertilization (IVF) treatment.
Her father and mother, John and Lesley, had tried for a baby for nine years before turning to the new technique, pioneered by gynecologist Patrick Steptoe and Cambridge University physiologist Robert Edwards.
Steptoe and Edwards became the first to successfully carry out IVF by extracting an egg, impregnating it with sperm and planting the resulting embryo back into the mother.
The Browns also had a second test-tube baby - daughter Natalie, 23, who became the first ever IVF baby to give birth herself in 1999. More than a million children have been born using IVF. "I don't feel any more special than anyone else," Brown said three years ago at an event celebrating her 25th birthday. "I just get on with my life - normal."