Perinatal and obstetric outcomes in singleton pregnancies following fresh versus cryopreserved blastocyst transfer: a meta-analysis

Abstract The transfer of cryopreserved blastocysts is increasing in IVF centres. However, little is known about the long-term perinatal and obstetric outcomes of this procedure. In the attempt to further elucidate these issues, we conducted a systematic review and meta-analysis comparing cryopreserved transfer with fresh blastocyst embryo transfer. The results show that the risk of both preterm (OR 0.89, 95% CI 0.80–0.99, p = 0.04) and low birth weight births (OR 0.82, 95% CI 0.68 – 0.99, p = 0.04) was significantly lower after cryopreserved blastocyst transfer than after fresh blastocyst transfer. The rate of large for gestational age births was significantly higher (OR 1.68, 95% CI 1.55 – 1.82, p