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Probability samples of area births versus clinic populations for reproductive epidemiology studies
Author(s) -
Savitz David A.,
Dole Nancy,
Kaczor Diane,
Herring Amy H.,
SiegaRiz Anna Maria,
Kaufman Jay,
Thorp John M.
Publication year - 2005
Publication title -
paediatric and perinatal epidemiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.667
H-Index - 88
eISSN - 1365-3016
pISSN - 0269-5022
DOI - 10.1111/j.1365-3016.2005.00649.x
Subject(s) - medicine , pregnancy , demography , epidemiology , prenatal care , obstetrics , low birth weight , population , environmental health , genetics , sociology , biology
Summary Studies of pregnancy outcome are generally based either on geographically defined populations, often from birth records, or on clinic or hospital populations. We compared women recruited into a clinic‐based study, the Pregnancy, Infection, and Nutrition (PIN) Study, with women who resided in the geographical area of the study (Alamance, Orange, and Wake Counties in North Carolina) and gave birth over the corresponding time period (1996–2000). Clinic participants were more likely to be Black, younger, have lower education, be unmarried, have a more frequent history of adverse pregnancy outcome, obtain prenatal care later, and smoke more cigarettes. Despite that profile, the proportion of clinic participants delivering preterm was somewhat lower than among area women overall (10.8% vs. 11.3%). Black/White risk ratios for preterm birth were markedly different for area (1.6) vs. clinic women (1.1), whereas other predictors were similar. Patterns may differ across groups for many reasons, including self‐selection of clinics and varying clinical practices.