Laboratory air quality may affect outcomes of assisted reproductive technologies (ART) (1, 2). Much of the published data is anecdotal or limited to pregnancy outcomes (3, 4). Additionally, improvement of IVF outcomes with the introduction of an air filter may be coincident with other improvements in the laboratory over time.
To examine parameters of embryo development before, during, and after a period when carbon filtration was unknowingly removed from our IVF laboratory air handler.
MATERIALS AND METHODS:
In this retrospective study, we analyzed fresh ART cycles from three periods: 1) February – July 2010, when the IVF lab air handler contained carbon filtration (“Carbon 1”), 2) February – July 2011, when carbon filtration was absent (“Absent”), and 3) February – July 2012, after carbon filtration had been restored (“Carbon 2”). HEPA filtration was in place throughout the study period, and no auxiliary (in-line or free-standing) air purification systems were employed. All embryo cultures were performed in 5.5-6.0% CO2 in air at 37°C in sequential culture media. The patient demographics and the rates of fertilization, cleavage, and blastocyst conversion per zygote following IVF or ICSI were compared. We also compared cleavage rates of PN stage embryos thawed during the three periods. Cleavage was defined as an embryo having ≥2 cells by 42 hours post insemination. One-way ANOVA was used to compare means with Games-Howell post-hoc analysis to confirm differences among groups. Chi-square tables were used to compare proportions. P values < 0.05 were considered statistically significant.
We reviewed 524 fresh ART cycles and 164 PN-stage thaw cycles. There were no statistically significant demographic differences between the Absent group and either of the Carbon groups. More ICSI was performed during the Absent and Carbon 2 periods, in response to poor fertilization rates with conventional insemination during the Absent period, which helped maintain fertilization rates. Fertilization and fresh embryo cleavage rates were adversely affected when carbon filtration was absent (Absent group). However, the cleavage rate of frozen PN embryos in the three groups did not differ significantly.
The absence of carbon filtration negatively affected fertilization and cleavage rates in fresh IVF cycles. Cleavage rate was significantly affected in fresh but not frozen cycles, suggesting that volatile organic compounds may negatively affect oocytes and zygotes preferentially.