Mode of Ascertainment is Critical in Assessing Safety of Percutaneous Umbilical Blood Sampling - Shulman, Lee P; Moretti, Michael L; Tharapel, Avirachan T; Shaver, David C; Mercer, Brian M; Sibai, Baha M; Meyers, Carole M; Phillips, Owen P; Dacus, John V; Barton, John R; Simpson, Joe Leigh; Elias, Sherman (American Journal of Perinatology, 1993)