Abstract
ObjectiveTo evaluate the influence of seasonal variation on in vitro fertilization (IVF) outcome in a large cohort population.Methods & materialsA total of 5,765 IVF cycles conducted in Sheba medical center between 2013 and 2016 were retrospectively analyzed. The treatment cycles included 4214 ovarian stimulation and ovum pick up (OPU) cycles of which 3020 resulted in fresh embryo transfer and 1551 vitrified- warmed cycles of which1400 resulted in warmed embryo transfer. Cycles were assigned to seasons according to the date of OPU for fresh embryo transfer cycles or according to the date of embryo warming for vitrified warmed embryo transfer cycles.ResultsThere were no statistically significant differences between the calendar months or seasons concerning the number of oocytes retrieved or fertilization rate in the fresh cycles. Throughout the 4 years of the study, the monthly clinical pregnancy rate fluctuated between 18.2% and 27.9% per fresh embryo transfer (mean 23.3%) and between 17.7% and 29.4% per vitrified warmed embryo transfer (mean 23%). These fluctuations did not follow any specific seasonal pattern.ConclusionsOur study did not demonstrate any significant influence of the calendar months or seasons on the clinical pregnancy rates of fresh or vitrified warmed embryo transfers. It might be speculated that the complete pharmaceutical control of the ovarian and endometrial function, as well as the homogeneous treatments, procedures and laboratory equipment used during the study period have lowered the influence of seasonal effect on IVF treatment outcome.
Highlights
Several epidemiologic studies throughout the world have demonstrated seasonal changes in natural conception and birth rate [1][2]
The treatment cycles included 4214 ovarian stimulation and ovum pick up (OPU) cycles of which 3020 resulted in fresh embryo transfer and 1551 vitrified- warmed cycles of which1400 resulted in warmed embryo transfer
Our study did not demonstrate any significant influence of the calendar months or seasons on the clinical pregnancy rates of fresh or vitrified warmed embryo transfers
Summary
Several epidemiologic studies throughout the world have demonstrated seasonal changes in natural conception and birth rate [1][2]. The seasonal related factors affecting natural conception include sperm quality, ovulation rate and social parameters. Evidence suggests that deterioration in sperm quality during the summer in sub-equatorial areas may result in lower conception rate and a reduction in birth rate in the spring [3][4]. Previous observations demonstrated an effect of environmental light exposure on female reproductive axis, ovulation and endometrial receptivity [5][6]. These observations were attributed to the variance in melatonin secretion, which increases in the darkness. In addition to the biologic seasonal variation, social parameters and patterns of sexual activity may influence reproduction and birth rate in human [2][7]
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