Female smoking does not affect live birth rate after frozen thawed blastocyst transfer cycle.

PURPOSE: The development of vitrification and blastocyst culture have recently led to a rapidly growing number of single frozen thawed blastocyst transfer (FBT) cycles worldwide. Although the impact of female smoking on spontaneous fertility is well established, its effect on assisted reproductive technologies (ART) outcome is still controversial, and no study has specifically evaluated its effect on FBT cycles' outcome.

METHODS: This retrospective study was conducted in all consecutive FBT cycles conducted between 2012 and 2021 in a single University-based ART centre. Endometrial preparation was standard and based on hormonal replacement therapy. One or two blastocysts were transferred according to couple's history and embryo quality. Female smoking status was recorded for each cycle, and the association between female smoking status and Live Birth Rate (LBR) after FBT cycle was evaluated with univariate and multivariate analysis.

RESULTS: A total of 1537 FBT cycles performed in non-smoking women and 397 FBT cycles performed in smoking women were included in the analysis. No independent association between female smoking status and LBR in FBT cycles was found after logistic regression (OR=1.07 [0.79-1.45], p=0.649).

CONCLUSION: Our study suggests that female smoking might not impair endometrial receptiveness in non-stimulated FBT cycles. Further studies should nevertheless consider assessing more precisely the current smoking exposure.