A single centre observational study into the segmentation of preimplantation genetic diagnosis (PGD) treatment by comparing cumulative pregnancy rates following cryopreservation of all genetically transferable embryos after PGD, compared to fresh embryo transfer cumulative with frozen embryo transfer of genetically transferable embryos.The primary aim of the study is to assess the feasibility and effectiveness of segmentation in terms of pregnancy rates. The secondary aim is to assess the logistic advantage of segmentation in PGD cycles.

Experimental questions

1. Is the cumulative live birth rate rate of a single PGD treatment when all genetically transferable embryos are cryopreserved by vitrification prior to consecutive in utero transfer in unstimulated cycles, superior to PGD treatment with fresh embryo transfer cumulative with transfer of supernumerary cryopreserved embryos?
2. Does the technique of segmentation allow better planning of DNA amplification and genetic analysis?

Design The proposed design is a pragmatic, prospective randomised controlled trial

Inclusion Criteria:

• 1st, 2nd or 3rd cycle of PGD in which embryo transfer was performed
• Indications for PGD: monogenic indications and X-linked disorders with a 25-50% risk of transmission and that are not associated with reduced ovarian response
• Normal ultrasound scan, i.e. presence of both ovaries, without evidence of abnormality within 6 months prior to randomisation.
• Regular menstrual cycles of 21-35 days, presumed to be ovulatory.

Exclusion Criteria:

• POLYCYSTIC OVARIAN SYNDROME (Rotterdam criteria *)

  * At least two of the following three features: (i) Oligo- and/or anovulation (ii) Clinical and/or biochemical signs of hyperandrogenism (iii) Polycystic ovaries and exclusion of other aetiologies (congenital adrenal hyperplasias, androgen-secreting tumours, Cushing's syndrome)

• Poor responders (Bologna criteria **)

  * * At least two of the following three features: (i) Advanced maternal age (≥40 years) or any other risk factor for poor ovarian response (POR); (ii) A previous POR (≤3 oocytes with a conventional stimulation protocol); (iii) An abnormal ovarian reserve test (i.e. antral follicle count (AFC) 5-7 follicles, or anti-Mullerian hormone (AMH) 0.5-1.1 ng/ml).

• Endocrine or metabolic abnormalities (pituitary, adrenal, pancreas, liver or kidney)

• anticipated high response: AMH >5.0 ng/ml or AFC >20

• Endometriosis ≥ grade 3

• Age > 40 years and 364 days