Effect of non-invasive preimplantation genetic testing for aneuploidies (ni-PGT) on cumulative ongoing pregnancy in infertile women of advanced maternal age: a multicentre, open-label, randomised controlled trial protocol

Introduction Embryo aneuploidy increases substantially with maternal age, contributing to implantation failure and miscarriage. Conventional morphological assessment cannot determine euploidy.

Non-invasive preimplantation genetic testing (ni-PGT) evaluates cell-free DNA in spent embryo culture medium, potentially improving embryo selection without trophectoderm biopsy. Robust evidence of clinical benefit in women aged 35 - 42 years remains limited.

Methods and analysis This is a multicentre, open-label, parallel-group randomised controlled trial conducted in three centres in China. Infertile women aged 35 - 42 years undergoing their first intracytoplasmic sperm injection cycle and having ≥2 good-quality days 5 - 6 blastocysts (Gardner grade ≥4BC,defined as an expansion grade of at least 4, with an inner cell mass grade of B or better and a trophectoderm grade of C or better) will be randomised 1:1 to ni-PGT-guided embryo selection or conventional morphology-based selection.

Randomisation will be stratified by study centre using variable permuted block sizes of 4 and 6 and implemented through a unified centralised randomisation system.