Obstetric and neonatal outcomes after frozen-thawed embryos transfer with laser-assisted hatching: a retrospective cohort study

Purpose: To ascertain if assisted hatching (AH) increases the risk of placenta-associated diseases and perinatal outcomes after frozen-thawed cleavage-stage embryo transfer.

Methods: We retrospectively evaluated 924 women who conceived with frozen-thawed cleavage-stage embryos transfer with (n = 390) or without (n = 534) laser-AH between 2013 and 2015. Data were obtained from the database on in vitro fertilization (IVF) patients in Shanghai First Maternity and Infant Hospital. We assessed neonatal (preterm birth, low birthweight, fetal macrosomia, stillbirth) and obstetric (miscarriage, ectopic pregnancy, post-term pregnancy, gestational diabetes (GDM), preeclampsia, intrahepatic cholestasis (ICP), placenta previa, placental abruption, premature rupture of membranes) outcomes.

Results: In twins, the median birthweight was lower in the AH group than that in the control group, and the prevalence of low birthweight (< 2500 g) was significantly higher in the AH group; after adjusting for maternal age, body mass index, mode of fertilization, and parity, no significant difference was found. In twins, no significant difference was detected in the prevalence of stillbirth or preterm pregnancy. In singleton births, there was no significant difference in the prevalence of low birthweight, macrosomia, preterm pregnancy or post-term pregnancy between the two groups. In singletons and twins, there were no significant differences in the prevalence of miscarriage, ectopic pregnancy, preeclampsia, GDM, ICP, or placenta abruption between the two groups.

Conclusions: AH is a relatively safe method and our study provides important information for using this method in carefully selected patients.