NCT03623659.

Study name	Does partial zona pellucida removal from vitrified‐warmed human blastocysts improve delivery rate in IVF? A multicentric RCT on laser assisted hatching
Methods	Randomised Parallel assignment Masking ‐ triple (participant, care provider, and outcome assessor)
Participants	700 participants 18 to 40 years old Female Inclusion criteria: single‐embryo transfer of vitrified/warmed blastocyst (SET); first or second frozen IVF (with or without intracytoplasmic sperm injection) cycle of blastocysts; first or second oocyte retrieval Exclusion criteria: pre‐implantation genetic testing (PGT) cycle; BMI > 35 kg/m²; severe male factor; abnormal uterine cavity
Interventions	Active comparator: AH group Subjects whose vitrified/warmed blastocysts will be subjected to treatment of laser‐assisted hatching Procedure: laser‐assisted hatching After warming, blastocysts are subjected to laser‐assisted hatching (LAH) following standard procedure. LAH procedure lasts 1 minute per blastocyst No intervention: control group Subjects whose vitrified/warmed blastocysts will be subjected to the same procedures except for treatment of laser‐assisted hatching
Outcomes	Primary outcome measures Delivery rate [time frame: 38 weeks after embryo transfer] Number of deliveries that result in a live birth per transferred blastocyst Secondary outcome measures Implantation rate [time frame: 6 to 7 weeks after transfer] • Number of gestational sacs observed at echographic screening at 6 weeks of pregnancy divided by the number of transferred embryos Clinical pregnancy rate [time frame: 4 weeks after transfer] • Ultrasonographic demonstration of an intrauterine gestational sac divided by the number of included women Biochemical pregnancy rate [time frame: 4 weeks after transfer] • Pregnancies failing to progress to the point of ultrasound confirmation divided by the number of women with a positive pregnancy test on blood Ongoing pregnancy rate [time frame: 20 weeks after transfer] • Ultrasonographic demonstration of an intrauterine gestational sac with fetal hearth divided by the number of included women Multiple pregnancy rate [time frame: 4 weeks after transfer] • Pregnancy in which more than 1 fetus develops in the uterus at the same time divided by the number of women with a clinical pregnancy Obstetrical and neonatal complication rates [time frame: after birth; 9 to 10 months after transfer] • Condition that adversely affects women and their fetal health during delivery Congenital anomalies rate [time frame: after birth, 9 to 10 months after transfer] • Birth defects, congenital disorders, congenital malformations, and congenital abnormalities are conditions of prenatal origin that are present at birth, potentially impacting an infant's health, development, and/or survival divided by the number of live births
Starting date	5 September 2018
Contact information	Alessandra Alteri; alteri.alessandra@hsr.it Paola Vigano; vigano.paola@hsr.it
Notes	ClinicalTrials.gov Identifier: NCT03623659 https://clinicaltrials.gov/ct2/show/NCT03623659?cond=assisted+hatching&draw=2&rank=4 Date first received 9 August 2018