Perinatal outcomes after vitrified-warmed day 5 blastocyst transfers compared to vitrified-warmed day 6 blastocyst transfers: A meta analysis

Abstract

Aims: The aim of this meta-analysis was to compare the perinatal outcomes between the vitrified-warmed day 5 blastocyst transfer (BT) and the vitrified-warmed day 6 blastocyst transfer (BT).

Methods: PubMed, EMBASE and the Cochrane Library were searched for the perinatal outcomes after in vitro fertilisation / intracytoplasmic sperm injection (IVF/ICSI) from inception to October 2018.The perinatal outcomes included birth weight, gestational age, number of males, premature delivery, birth defects, and neonatal deaths. We used a random effect model to analyse the summary risk ratios (RRs) and mean difference (WMD) with 95 % confidence intervals (CIs).

Results: Eight retrospective studies that met the inclusion criteria were included. Compared with vitrified-warmed day 5 BT, vitrified-warmed day 6 BT was associated with increased birth weight (WMD = -80.39; 95 % CI = -151.8 to -8.97; I² = 41 %, P = 0.03);There was no significant difference in gestational age (WMD = 0.10; 95 % CI =-0.07-0.27; I² = 0%, P = 0.24), number of males (RR 0.93, 95 % CI 0.78-1.10; I² = 43 %), premature delivery (RR 0.84, 95 % CI 0.13-5.27; I² = 72 %), birth defects (RR 1.48, 95 % CI 0.71-3.11; I² = 0%) and neonatal deaths (RR 1.2, 95 % CI 0.25-5.71; I² = 0%) between the two groups.

Conclusions: Vitrified-warmed day 6 BT is associated with increased birth weight rather than day 5 BT. There was no difference in gestational age, number of males, premature deliveries, birth defects, and neonatal death, between the two groups. These results concluded that vitrified-warmed day 6 BT has no difference compared with vitrified-warmed day 5 BT in regard to adverse impact on perinatal outcomes.

Keywords: Blastocyst transfer; Meta-analysis; Perinatal outcome; Vitrified-warmed.