P-689 Reproductive outcomes in letrozole-stimulated vs artificial frozen-thawed embryo transfer cycles in women with PCOS and/or oligo-anovulation: a systematic review and meta-analysis.

Abstract Study question Does stimulation with letrozole improve reproductive outcomes compared to artificial endometrial preparation before frozen-thawed embryo transfer (FET) in women PCOS and/or oligo-anovulation? Summary answer Live birth rate (LBR) was significantly improved FET and oligo-anovulatory women. What is known already Letrozole, an aromatase inhibitor reducing oestradiol levels, has been shown increase live LBR clomiphene citrate PCOS/anovulatory intrauterine insemination. There now growing interest its potential value improving cycles as well. Furthermore, recent studies indicate increased risk of hypertensive disorders pregnancies that have arisen following the absence a corpus luteum. Letrozole offers alternative approach cycle progesterone oligo-anovulation preserved ovarian reserve, ensuring luteum, which may outcomes. design, size, duration A systematic review published PubMed or Cochrane library up until 14th October 2022. Randomised controlled trials cohort comparing letrozole-stimulated were included. Screening, data extraction, quality assessment done independently by two reviewers using Robins-I tool Handbook. The study registered PROSPERO, collection reporting followed PRISMA guidelines. Participants/materials, setting, methods Women according Rotterdam Criteria Letrozole-stimulated without adjuvant gonadotrophins luteal phase support included comparison for FET. Random-effect meta-analyses conducted Review Manager. Dichotomous variables summarised Mantel-Haenszel ratio, heterogeneity evaluated Forest plots I2-statistic. Funnel used assess publication bias all Main results role chance search identified 62 studies, 23 relevant full-text scrutinized, total 10 fulfilled inclusion criteria appropriate control group. Five observational oligo/anovulation, one randomised trial four criteria, but no further information on ovulation pattern. Except three standard if follicular response poor. In received support. 7% higher vs groups (95% CI: (3%;10%), I2= 56%, P=0.0001) similar effects subgroup analysis (7 n = 3931 letrozole-treated women). ongoing pregnancy 10% (4%;16%), 1%, P=0.001) (4 297 Definition miscarriage biochemical loss varied extent where meta-analysis could not be performed. Nevertheless, seven reported rate, six showed rates lower letrozole. No raised concerns funnel plots. Limitations, reasons caution Most high bias, substantial observed amongst dilute evidence. Some clarifying ovulatory anovulatory. plot each outcome suspicion bias. Wider implications findings improves ongoing-pregnancy-rate preparation. However, robust evidence lacking RCTs restricted are urgently needed. insufficient conclude whether required after Trial registration number Not applicable