Secular variation and risk factors of preterm birth in Hainan, the Free Trade Port in China from 2010 to 2021

Preterm delivery rates have increased obviously worldwide over the past decade, yet reliable epidemiological studies on the incidence of preterm birth and temporal trends are not available in Hainan, The Free Trade Port in China. We aimed to describe the rate of preterm birth and trends between 2010 and 2021 and to primarily explore risk factors associated with preterm birth in Hainan, China. This was an observational study was based on data from the Hainan Provincial Birth Certificate System (HPBCS) for live births between 1 January 2010 and 31 December 2021. We included pregnancies resulting in at least one live birth, with newborns born at a gestational age of 28 weeks or greater, or with a birth weight of 1000 g or more. The outcome were preterm birth rates and their trends over time. Potential risk factors were collected, including infant gender, maternal age, paternal age, maternal ethnicity, paternal ethnicity, home address, and single or multiple pregnancies. The logistic regression model was used to assess the relationship between preterm birth and potential risk factors. A total of 1,537,239 live births and 86,328 preterm births were investigated, giving a total preterm birth rate of 5.62%. The overall preterm birth rate increased from 4.47% in 2010 to 7.12% in 2021 (compound annual growth rate [CAGR] 4.32). The CAGR of late preterm birth is consistent with the overall preterm birth rate (4.32%). The fastest growth is observed in the rate of very preterm births (5.53%), while the rate of moderate preterm births exhibits the slowest growth (3.87%). Infant gender, multiple pregnancy, home address, parental age, and ethnicity had significant effects on preterm birth. The preterm birth rate was increasing year by year from 2010 to 2021 in Hainan, The Free Trade Port in China. Incidence of preterm births in Hainan Province in relation to multiple pregnancies, infant sex, parental age, parental race and residential address.