A population-based, cross-sectional study using data on women that deliered singleton births between 20 and 43 weeks in Missouri (1989-1997) was conducted (n = 626,883).
A population-based, cross-sectional study using data on women that deliered singleton births between 20 and 43 weeks in Missouri (1989-1997) was conducted (n = 626,883).
本研究基于人口学的横断面研究。所选择的对象是1989-1997年密苏里州生育一胎的妇女，年龄由20岁-43岁。