Are the outcomes of assisted reproductive technology affected by seasonal changes?

Rasool Hassanzadeh,1,* Maryam asgharnia,2 Zahra atrkarroushan,3 Marzieh mehrafza,4 Mohammad hadi bahadori,5 Fatemeh hosseinzadeh,6

1. Student Research Committee, Guilan University of Medical Sciences, Rasht, Iran
2. Department of obstetrics and gynecology, Guilan University of Medical Sciences, Rasht, Iran
3. Department of Social Medicine and Health, Guilan University of Medical Sciences, Rasht, Iran
4. Mehr Medical Innovative technologies Institute, Research and Clinical Center for Infertility, Rasht, Iran
5. Department of anatomy, Faculty of medicine, Guilan University of Medical Sciences, Rasht, Iran
6.

Abstract

Introduction

Several epidemiological studies noted a variation in natural conception and birth rates not only in animals but also in human. the existence of a seasonal influence on the outcome of human assisted reproductive technology is still debated. according to conflicting data, we aimed to investigate whether the outcomes of intracytoplasmic sperm injection (icsi) are affected by seasonal changes or not.

Methods

In a retrospective cohort study, a total of 3670 patients undergoing their first icsi between the years 2012 and 2016 were divided into four season-groups according to the date of the beginning of stimulation. the mean of retrieved oocytes, embryos transferred and mii oocytes and percentage of fertilization, implantation, and pregnancy rates was compared among these groups and the influence of each season on these parameters was evaluated. data analysis was performed using spss version 21. chi-square test and one way analysis of variance (anova) were used for statistical analysis and p value<0.05 was considered significant.

Results

The women were in average age of 34.99±6.55 years. 76 % of them had primary infertility and the rest had secondary infertility. the mean duration of infertility was 6.11±5.34 years. the indications for treatment were female factor, male factor, both male and female factors and unexplained in 44.15%, 37.15%, 10.05% and 8.65%, respectively. the percentage of pregnancy rate was significantly higher during summer than other seasons. (spring: 36.9%, summer: 44.5%, fall: 38.3, winter: 43.9%, p=0.001). the percentage of implantation rate was significantly higher during summer than other seasons (p=0.0001). there wasn't any statistically significant difference among the groups in terms of fertilization rate and embryos transferred. the mean of retrieved oocytes and mii oocytes varied significantly within the different seasons and was highest in summer (p=0.004 and p=0.015, respectively).

Conclusion

Our study demonstrated statistically significant differences in icsi outcomes such as pregnancy rate, implantation rate, retrieved oocytes and mii oocytes according to season and we saw better results in summer. therefore a change of routine fertility treatments concerning the season should be taken into consideration.

Keywords

Intracytoplasmic sperm injection, implantation, fertilization, pregnancy, seasonality