A pre-conception cohort study of fertility and its related factors among couples with the intention of conception

Abstract

Objective: To describe fertility and explore factors associated with it among pre-conception couples of childbearing age. Methods: Based on the pre-conceptional offspring trajectory study of the School of Public Health of Fudan University, couples of childbearing age who participated in the pre-conception physical examination in Shanghai Jiading District from 2016 to 2021 were recruited and followed up. Couples' time to pregnancy (TTP) was analyzed and Cox proportional hazards regression model was used to explore the factors associated with TTP. Kaplan-Meier was used to calculate each menstrual cycle's cumulative pregnancy rate. Results: A total of 1 095 preconception couples were included in the analysis, the M(Q1,Q3)of TTP was 4.33 (2.41, 9.78) menstrual cycles. Age of women (FR=0.90, 95%CI: 0.85-0.95, P<0.001), women who were overweight or obese before pregnancy (FR=0.36, 95%CI: 0.24-0.55, P<0.001), women who were exposed to second-hand smoking (FR=0.63, 95%CI: 0.44-0.92, P=0.016), women whose home or office had been renovated in the past 2 years and had a particular smell (FR=0.46, 95%CI: 0.26-0.81, P=0.008) were risk factors for impaired fertility. Regular menstrual cycles (FR=1.64, 95%CI: 1.16-2.31, P=0.005), females who often drank tea/coffee (FR=1.55, 95%CI: 1.11-2.17, P=0.011) and males who took folic acid before conception (FR=2.35, 95%CI: 1.38-4.23, P=0.002) were associated with better fertility. The cumulative pregnancy rate of 3, 6, and 12 menstrual cycles was 37.6%, 64.4%, and 78.4%, respectively. Conclusion: Older couples, overweight or obesity before pregnancy, irregular menstruation, exposure to secondhand smoke and decoration pollutants in females are associated with impaired fertility. Frequent tea/coffee drinking before pregnancy in females and taking folic acid before pregnancy in males are associated with shortened conception time.