Prevalence and Risk Factors of Infertility at a Rural Site of Northern China

Objective To investigate and analyze prevalence and risk factors of infertility at a representative rural site of Northern China. Method This is a cross-sectional study. We conducted a face-to-face questionnaire survey from July 2014 to October 2014 involving 5,131 women who were at childbearing age in Suizhong, a medium-sized, representative county located in Northern China. Finally, data from 4,232 valid questionnaires were analyzed. Definition Infertility is defined as the failure to achieve a clinical pregnancy after 12 months or more of regularly unprotected sexual intercourse. Results Infertility prevalence in Suizhong County was 13.09% (95% CI, 12.09%-14.1%), of which the primary infertility incidence was 0.99% (95% CI, 0.72%-1.34%), and the secondary infertility incidence was 12.10% (95% CI, 11.13%-13.12%). For women, the infertility incidence of underweight women (Body Mass Index, BMI<18.5 kg/m(2)) was 1.5-fold higher than that of women with moderate BMI (18.5-24.9 kg/m(2)). The infertility incidence of women with little exercise was 4 times more than that of women with regular exercise, and 2 times more than that of women with heavy exercise. The group with moderate menstrual flow had the lowest prevalence of infertility, while both scant and excessive menstruation led to increased infertility incidence. Number of pregnancies (OR = 0.63; 95% CI, 0.51-0.79) was a protective factor for infertility, while the number of abortions (OR = 2.15; 95% CI, 1.58-2.93) was a risk factor for infertility. For men, those who stayed up late at night more than 3 times per week showed a significantly higher infertility incidence. Men who engaged in occupations with high-temperature working environment also suffered from an infertility incidence of about four times more than the others. Conclusions We found significant association between women's infertility incidence with their BMI, state of exercise, amount of menstrual flow, number of pregnancies and number of abortions. As for men, both staying up late and engaging in high-temperature occupations are independent factors affecting their fertility.