Determinants of participation in an epidemiological study of preterm delivery

We describe the study design and patterns of participation for a cohort stu dy of preterm delivery, focused on genital tract infections, nutrition, tob acco use, illicit drugs and psychosocial stress. Women are recruited at 24- 29 weeks' gestation from prenatal clinics at a teaching hospital and a coun ty health department. We recruited 57% of the first 1843 eligible women; 29 % refused and 8% could not be contacted. White women were somewhat more lik ely to participate than African-American women (61% vs. 54% respectively). More notable differences were found comparing teaching hospital and health department clinics (71% vs. 47% participation respectively), with the healt h department clinic having a greater proportion refuse (24% vs. 33%) and mo re women who could not be contacted (4% vs. 11%). Participation was affecte d only minimally by day or timing of recruitment, but inability to contact diminished substantially as the study continued (13-0%). Refusals were larg ely unrelated to patient attributes. Lower education predicted inability to contact. Risk of preterm delivery was 14% among recruited women, 10% among women who refused, and 15% among women whom we were not able to contact, d emonstrating that, overall, risk status was not lower among recruited women .