Katherine J Sapra1, Ashok K Chaurasia2, Jennifer A Hutcheon3, Katherine A Ahrens4. 1. Department of Obstetrics and Gynecology, Weill Cornell Medical College, New York, NY. 2. School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, Canada. 3. Department of Obstetrics and Gynaecology, University of British Columbia, Vancouver, BC, Canada. 4. Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, MD.
Abstract
BACKGROUND: Epidemiologic studies examining preconception risk factors on perinatal outcomes are typically restricted to livebirths. By including only non-terminated pregnancies, estimates for the underlying pregnancy cohort may be subject to selection bias. We examined if potential selection bias due to induced termination by maternal race may result in different estimates of the non-Hispanic black - non-Hispanic white risk ratio (RR) for preterm delivery (PTD) among a reconstructed pregnancy cohort ('pseudo-pregnancy cohort'). METHODS: Using New York City registries of 1.6 million livebirths, spontaneous terminations, and induced terminations among non-Hispanic black and non-Hispanic white women (2000-12), we multiply imputed PTD (<37 weeks) and early PTD (<32 weeks) outcomes for induced terminations based on maternal race, age, parity, marital status, nativity, and medical care payer to construct the pseudo-pregnancy cohort. RESULTS: Among non-Hispanic black and non-Hispanic white women, 55% and 19% of pregnancies ended in induced termination and 13% and 8% resulted in PTD, respectively. Although several factors were associated with both PTD and induced termination, PTD RRs in the birth (RR 1.64, 95% confidence interval (CI) 1.62, 1.66) and pseudo-pregnancy (RR 1.63, 95% CI 1.56, 1.71) cohorts were similar. However, early PTD RR was somewhat larger in the birth (RR 2.80, 95% CI 2.71, 2.89) than pseudo-pregnancy (RR 2.47, 95% CI 2.23, 2.73) cohort. CONCLUSIONS: Using birth certificate data - thereby excluding induced terminations - to estimate the PTD racial disparity did not produce biased estimates. Our data suggest observed PTD disparities likely are not artefacts of selection bias due to induced termination.
BACKGROUND: Epidemiologic studies examining preconception risk factors on perinatal outcomes are typically restricted to livebirths. By including only non-terminated pregnancies, estimates for the underlying pregnancy cohort may be subject to selection bias. We examined if potential selection bias due to induced termination by maternal race may result in different estimates of the non-Hispanic black - non-Hispanic white risk ratio (RR) for preterm delivery (PTD) among a reconstructed pregnancy cohort ('pseudo-pregnancy cohort'). METHODS: Using New York City registries of 1.6 million livebirths, spontaneous terminations, and induced terminations among non-Hispanic black and non-Hispanic white women (2000-12), we multiply imputed PTD (<37 weeks) and early PTD (<32 weeks) outcomes for induced terminations based on maternal race, age, parity, marital status, nativity, and medical care payer to construct the pseudo-pregnancy cohort. RESULTS: Among non-Hispanic black and non-Hispanic white women, 55% and 19% of pregnancies ended in induced termination and 13% and 8% resulted in PTD, respectively. Although several factors were associated with both PTD and induced termination, PTD RRs in the birth (RR 1.64, 95% confidence interval (CI) 1.62, 1.66) and pseudo-pregnancy (RR 1.63, 95% CI 1.56, 1.71) cohorts were similar. However, early PTD RR was somewhat larger in the birth (RR 2.80, 95% CI 2.71, 2.89) than pseudo-pregnancy (RR 2.47, 95% CI 2.23, 2.73) cohort. CONCLUSIONS: Using birth certificate data - thereby excluding induced terminations - to estimate the PTD racial disparity did not produce biased estimates. Our data suggest observed PTD disparities likely are not artefacts of selection bias due to induced termination.
Authors: Daniel Grossman; Sarah Baum; Liza Fuentes; Kari White; Kristine Hopkins; Amanda Stevenson; Joseph E Potter Journal: Contraception Date: 2014-07-22 Impact factor: 3.375
Authors: Joyce A Martin; Brady E Hamilton; Paul D Sutton; Stephanie J Ventura; T J Mathews; Sharon Kirmeyer; Michelle J K Osterman Journal: Natl Vital Stat Rep Date: 2010-08-09
Authors: Sudeshna Mukherjee; Digna R Velez Edwards; Donna D Baird; David A Savitz; Katherine E Hartmann Journal: Am J Epidemiol Date: 2013-04-04 Impact factor: 4.897
Authors: A J Wilcox; C R Weinberg; J F O'Connor; D D Baird; J P Schlatterer; R E Canfield; E G Armstrong; B C Nisula Journal: N Engl J Med Date: 1988-07-28 Impact factor: 91.245