Birthday is a treat for statisticians

Ben Oakhill's seventh birthday will be a medical milestone. His celebrations a week today will herald the countdown for an international statistical marathon which will end as the millennium gets under way.

Ben, of Patchway, near Bristol, was the first child of more than 14,000 to take part in the Children of the Nineties - the world's largest study of child health and development.

Based at Bristol University's Institute of Child Health, it has been charting the progress of 14,893 expectant mothers in the former county of Avon through their children's births to their seventh birthdays. The multi-million pound project is the core of a study also involving Russia, Ukraine, Slovakia, the Czech Republic, Greece and the Isle of Man. It was scheduled to begin in April 1991, but Ben's premature birth - when he weighed 2lb 6oz - in December gave it an early start.

His mother, Margaret, and the other volunteer mothers regularly filled in questionnaires about their lifestyle and health, to build a massive database of life and health in the Nineties. Now the research team is planning full medical check-ups of more than 14,000 children at special clinics starting next August, involving more than 100 researchers and support staff.The data should be ready for analysis early in 2000.