Référence bibliographique 
Kramer, Michael S., Wilkins, Russell, Goulet, Lise, Séguin, Louise, Lydon, John, Kahn, Susan R., McNamara, Helen, Dassa, Clément, Dahhou, Mourad, Masse, André, Miner, Louise, Asselin, Guylaine, Gauthier, Henriette, Ghanem, Antoinette, Benjamin, Alice et Platt, Robert W. 2009. «Investigating Socio-Economic Disparities in Preterm Birth: Evidence for Selective Study Participation and Selection Bias ». Pediatric and Perinatal Epidemiology, vol. 23, no 4, p. 301-309.
«Selective study participation can theoretically lead to selection bias. We explored this issue in the context of a multicentre cohort study of socio-economic disparities in preterm birth.» (p. 301)
5146 women with singleton pregnancies
108 724 Montreal Census Metropolitan Area (CMA) singleton births for 1998–2000
Type de traitement des données :
«Women with singleton pregnancies were recruited from four large Montreal maternity hospitals and invited to return for an interview, vaginal examination and venepuncture at 24–26 weeks of gestation. We compared the observed preterm birth rate (ultrasound confirmed) among [this] cohort women to that expected based on all [CMA] singleton births [...].» (p. 301) «Within each stratum of maternal education and neighbourhood income [...], cohort women had substantially lower rates of preterm birth than women from the CMA. No significant association between socio-economic status (SES) and preterm birth was observed in the study cohort, except among ‘indicated’ (non-spontaneous) cases. [...] We speculate that the lower-than-expected preterm birth rate and attenuated association between neighbourhood income and preterm birth may be related to selective participation by women more psychologically invested in their pregnancies. Investigators should consider the potential for biased associations in pregnancy/birth cohort studies, especially associations based on SES or race/ethnicity, and carry out sensitivity analyses to gauge their effects.» (p. 301)