Objective: To investigate the effect of improved air quality on IVF and subsequent embryo development. Design: Retrospective cohort study. Setting: Hospital-based IVF facility composed of an anteroom, a cleanroom, and an adjacent operating room. Patient(s): Two-hundred seventy-five couples requesting IVF between 1993 and 1997. Intervention(s): None. Main Outcome Measure(s): Particle counts (sizes 0.3, 0.5, 1.0, and 5.0 mu m); IVF rates; and embryo quality (stage and grade). Result(s): Clinical pregnancy rates decreased from 35% in 1993 to 16% in 1994 (numerous construction odors were detected during 1994) and increased steadily after the cleanroom was built (rates for 1995-1997 were 20%. 32%, and 59%, respectively). Fertilization rates decreased between 1993 (74%) and 1994 (60%) and then steadily increased after cleanroom installation (62% in 1995, 71% in 1996, and 69% in 1997). The proportion of embryos past the four-cell stage decreased from 66% in 1993 to 61% in 1994 bur then increased steadily in the years after the cleanroom was built (78%, 77%, and 83% in 1995, 1996, and 1997, respectively). During the same 5-year period, there were no differences in embryo quality or number of embryos transferred. Conclusion(s): Construction of a Class 100 cleanroom improved air quality and IVF rate and increased the number of embryos past the four-cell stage available for transfer. (C) 1998 by American Society for Reproductive Medicine.
