212Dose-response association and interaction between physical activity and sedentary time on premature rupture of membranes

Background Premature rupture of membranes (PROM) is a common pregnancy complication with multifactorial etiology. However, associations between physical activity (PA) and PROM are still unclear. Therefore, this study aims to explore the dose-response relationship and interactions between PA frequency, sedentary time (ST) and PROM. Methods Data on 6848 pregnant women were obtained from the Chinese Pregnant Women Cohort Study. Participants were recruited from July 2017 to November 2018 and were followed up until delivery. The International Physical Activity Questionnaire-Short Form was used to assess the frequency of PA and ST. Logistic regression and restricted cubic spline (RCS) model were used for data analyses. Results Women with frequencies of over 4 days/week of moderate-intensity PA (OR:1.50, 95%CI:1.01∼2.23) and light-intensity PA (OR:1.19, 95%CI:1.04∼1.37) had higher risks of PROM respectively. The RCS model showed that the risk for PROM was significant with frequencies of over 2 days/week of vigorous-intensity PA, over 5 days/week of moderate-intensity PA or over 5 days/week of light-intensity PA (ORs with 95%CI >1). Interactions analyses showed that risks for PROM increased with frequencies of moderate-intensity and light-intensity PA both over 4 days/week (OR:1.80, 95%CI:1.17∼2.77), or with a frequency of light-intensity PA of over 4 days/week and ST of over 6 hours/day (OR:1.36, 95%CI:1.10∼1.69). Conclusions It is necessary to propose a suitable recommendation of frequency and intensity of PA, and identify and propose the corresponding intervention ways to reduce and prevent PROM occurrence during pregnancy. Key messages There is a dose-response relationship and interaction between PA and ST on PROM.