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[A propensity score-matched study on relationship between maternal respiratory infection in early pregnancy and gestational age].

Objective: To explore the association between maternal respiratory infection in early pregnancy and gestational age of single live birth. Methods: A face to face questionnaire survey was conducted among child bearing aged women in 30 counties (district) of Shaanxi province selected through stratified multistage sampling. Propensity score (PS) matched (1∶1) analysis was used to match participants with respiratory infections to those without respiratory infections. A multilevel linear model was used to investigate the association between respiratory infections and gestational age. Through the control of the confounders step by step, three models were established in this study: model 1 for the variable of respiratory infections before PS matching, model 2 was adjusted for variables in model 1 plus some other individual differences of mother and baby, and model 3 for the variable of respiratory infections after PS matching. Results: Of 28 848 child bearing aged women surveyed, 3 676 (12.74%) had respiratory infections in early pregnancy. After PS matching, 2 762 pairs were matched. Analysis with model 1 indicated that a decrease of 0.111 week (P<0.001) in gestational age was associated with a respiratory infection during the first trimester. Analysis with model 2 and model 3 indicated that a decrease of 0.058 week (P=0.025) and a decrease of 0.076 week (P=0.036) were associated with respiratory infection during the first trimester, respectively. Conclusion: The respiratory infection during the first trimester was associated with the decrease of the gestational age of newborn.