[1] Tokyo Womens Med Univ, Sch Med, Dept Legal Med, Shinjuku Ku, Tokyo 1628666, Japan
[2] Tokyo Womens Med Univ, Sch Med, Maternal & Perinatal Ctr, Shinjuku Ku, Tokyo 1628666, Japan
[3] SIDS Family Assoc Japan, Shibuya, Japan
[4] St Marianna Univ, Sch Med, Dept Pediat, Kawasaki, Kanagawa, Japan
[5] Chinese Univ Hong Kong, Dept Pediat, Shatin, Hong Kong, Peoples R China