科研之友
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摘要
OBJECTIVE: The association between obesity and spontaneous preterm births (sPTBs) has been shown to be influenced by obesity-attendant comorbidities. Our objective was to better understand the complex relationship of obesity and its attendant comorbidities with sPTBs. STUDY DESIGN: A retrospective analysis utilizing maternally linked hospital and birth certificate records of 2 049 196 singleton California deliveries from 2007 to 2011. Adjusted relative risks (aRRs) for sPTBs were estimated using multivariate Poisson regression modeling. RESULTS: Obese women had higher aRRs for sPTBs than their normal body mass index (BMI) controls. aRRs (95% confidence interval) increased with increasing BMI category: Obese I = 1.10 (1.08 to 1.12); Obese II = 1.15 (1.12 to 1.18); and Obese III = 1.26 (1.22 to 1.30). When comparing only obese women without comorbidities to their normal BMI controls, aRRs reversed, that is, obese women had lower aRRs of sPTBs: Obese I = 0.96 (0.94 to 0.98), Obese II = 0.95 (0.91 to 0.98); and Obese III = 0.98 (0.94 to 1.03). This same reversal of aRR direction was also observed among women with comorbidities: 0.92 (0.89 to 0.96); 0.89 (0.85 to 0.93); and 0.89 (0.85 to 0.93), respectively. Increasing BMI increased the aRRs for sPTBs among patients with gestational diabetes (P < 0.05), while decreasing the risk among patients with chronic hypertension and pregnancy-related hypertensive disease (P < 0.05). CONCLUSIONS: The obesity and preterm birth paradox is an example of what has been described as ' Simpson's Paradox'. Unmeasured confounding factors mediated by comorbidities may explain the observed protective effect of obesity upon conditioning on the presence or absence of comorbidities and thus resolve the paradox.
- 出版日期2017-10
