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

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.

Genetic diversity and structure of the threatened species Sinopodophyllum hexandrum (Royle) Ying.

Sinopodophyllum hexandrum is an important medicinal plant that has been listed as an endangered species, making the conservation of its genetic diversity a priority. Therefore, the genetic diversity and population structure of S. hexandrum was investigated through inter-simple sequence repeat analysis of eight natural populations. Eleven selected primers generated 141 discernible fragments. The percentage of polymorphic bands was 37.59% at the species level, and 7.66-24.32% at the population level. Genetic diversity of S. hexandrum was low within populations (average HE = 0.0366), but higher at the species level (HE = 0.0963). Clear structure and high genetic differentiation were detected between populations using unweighted pair groups mean arithmetic and principle coordinate analysis. Clustering approaches clustered the eight sampled populations into three major groups, and AMOVA confirmed there to be significant variation between populations (63.27%). Genetic differentiation may have arisen through limited gene flow (Nm = 0.3317) in this species. Isolation by distance among populations was determined by comparing genetic distance versus geographical distance using the Mantel test. The results revealed no correlation between spatial pattern and geographic location. Given the low within-population genetic diversity, high differentiation among populations, and the increasing anthropogenic pressure on this species, in situ conservation measures, in addition to sampling and ex situ preservation, are recommended to preserve S. hexandrum populations and to retain their genetic diversity.