TY - JOUR T1 - Recent versus historical trends in preterm birth in Canada JF - Canadian Medical Association Journal JO - CMAJ SP - 1409 LP - 1409 VL - 161 IS - 11 AU - K. S. Joseph AU - Michael S. Kramer Y1 - 1999/11/30 UR - http://www.cmaj.ca/content/161/11/1409.abstract ER -