Assisted hatching decreases pregnancy outcomes in vitrified donor oocytes.

OBJECTIVE

To evaluate the impact of assisted hatching on implantation and pregnancy rates among fresh embryo transfers using vitrified donor oocytes.

DESIGN

Retrospective cohort study.

SUBJECTS: Oocyte donor recipients.

EXPOSURE: Assisted hatching.

MAIN OUTCOME MEASURES: Rates of implantation, clinical pregnancy, spontaneous abortion, and ongoing pregnancy.

RESULTS

Among the 2,617 embryos, 1,668 (64%) underwent assisted hatching. The biochemical pregnancy rate per transfer and clinical pregnancy rate per transfer were significantly lower for the assisted hatching group vs. non-assisted hatching group (72% vs. 76%; adjusted risk ratio (aRR), 0.94; 95% confidence interval [CI], 0.9-0.99 and 61% vs. 66%; aRR, 0.92; 95% CI, 0.86-0.97). The assisted hatching group also had a lower ongoing/sustained pregnancy rate (57% vs. 62%; aRR, 0.91; 95% CI, 0.78-0.91) compared with the non-assisted hatching group. Spontaneous abortion may be higher for the assisted hatching group compared with the non-assisted hatching group, although not statistically significant (13% vs. 11%).

CONCLUSION

Assisted hatching may be associated with decreased clinical and ongoing pregnancy rates in donor oocyte cycles.