[1] Canadian Neonatal Network Coordinating Ctr, Vancouver, BC V6H 3V4, Canada
[2] Univ British Columbia, Dept Pediat, Vancouver, BC V6T 1W5, Canada
[3] McGill Univ, Dept Pediat, Montreal, PQ H3A 2T5, Canada
[4] St Marys Hosp, Dept Pediat, Portsmouth PO3 6AQ, Hants, England
[5] Ctr Community Hlth & Hlth Evaluat Res, Vancouver, BC, Canada