Seasonality and humanin vitrofertilization outcome

Abstract

Seasonal changes in spontaneous fecundity have been observed in several human populations, but it is not clear whether the same applies to human in vitro fertilization-embryo transfer (IVF) procedures. In the present study, 2067 patients undergoing their first IVF attempt between the years 1998 and 2003 were grouped into four 'seasons' (December-February, March-May, June-August, September-November) according to the day on which they were administered human chorionic gonadotropin. Several parameters known to affect IVF outcome (including ovarian response to gonadotropins, sperm and oocyte quality, fertilization rate, embryo quality, pregnancy and implantation rates) were considered and potential changes among the four seasonal periods were analyzed. Moreover, some confounding variables (sperm quality, age, duration of infertility, indications for IVF) were controlled for. Overall, pregnancy rate per oocyte pick-up and per embryo transfer of 32.5% and 35.8%, respectively, as well as implantation rate of 18.9%, were recorded. None of the observed IVF-related parameters showed any significant change clearly related to a specific seasonal period, their fluctuations throughout the year being randomly determined. Ovarian responsiveness to gonadotropins, quality of gametes and embryos, and fertilization and implantation processes were apparently not significantly affected by seasonality. It is concluded that the results of a good-quality IVF program in humans are not significantly affected by the season of the year in which the IVF attempt is accomplished; therefore, season is not a relevant factor to be considered when planning an IVF treatment.

Influence of seasonal variation on in vitro fertilization success

“…Likewise, there was no significant difference in the endometrial receptivity between the seasons, demonstrated by the similar pregnancy rates in the vitrified warmed cycles. This lack of seasonal influence, was also demonstrated in previous studies [ 11 , 12 , 14 ]. Unlike previous studies, we chose to analyze separately the seasonal effect on fresh embryo transfer cycles and on vitrified warmed cycles.…”

“…On the other hand, other studies failed to demonstrate any specific seasonal patterns regarding IVF treatment outcomes. Gindes et al [ 11 ] and Revelli et al [ 12 ] found that neither fertilization, nor implantation rate in fresh embryo transfer cycles were affected by the season of the year. To avoid bias in the fertilization rate, Wunder et al excluded cycles using ICSI and examined only IVF cycles, showing no effect of seasons on treatment outcome [ 13 ].…”

The effects of daily meteorological perturbation on pregnancy outcome: follow-up of a cohort of young women undergoing IVF treatment

“…Besides the factors of ovarian stimulation protocol and age as discussed above, the previous studies did not catch the essence of seasonal variation — temperature, humidity, sunlight duration, and solar radiation. For example, previous studies [21, 24, 25] analyzed the pregnancy outcome in different months ignoring the detailed meteorological perturbation in these durations. Although in the same season, the climates may vary from different years.…”

Seasonality in sperm parameters in normal men and dyspermic patients on medical intervention

“…In the human, seasonal variations in reproductive performance as judged by changes in the relative and absolute number of natural conceptions and deliveries have been observed in certain epidemiological studies (Rojansky et al, 1992;Huber et al, 2004), but not in conditions of in vitro fertilisation treatment (Revelli et al, 2005). Moreover, not only other reproductive events such as e.g.…”