Clomiphene citrate vs. letrozole for cryopreserved-thawed embryo transfer: A randomized, controlled trial
Sarah Racine IVF Unit, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel. The Journal of reproductive medicine
(Impact Factor: 0.7).
To assess the endometrial thickness, hormonal status and pregnancy rates with clomiphene citrate (CC) vs. letrozole in frozen-thawed embryo transfer protocols.
Nineteen patients who had previously undergone in vitro fertilization (IVF) with embryo cryopreservation were prospectively and randomly enrolled in a randomized, controlled trial. Nine patients were treated with CC, 100 mg per day, from day 3 to day 7 of the cycle, and 10 patients were treated with letrozole, 2.5 mg per day, on the same cycle days. beta-Human chorionic gonadotropin (beta-hCG) was administrated when the leading follicular size was > or = 18 mm. Endometrial thickness was measured on cycle day 8, beta-hCG day, transfer day and 7 days after embryo transfer. Estradiol levels were determined on the day of beta-hCG administration.
Patients' ages and number of previous unsuccessful IVF cycles were similar between the 2 groups. Endometrial thickness was significantly higher in the letrozole group as compared to the CC group on the day of beta-hCG administration (9.1 +/- 3.6 vs. 6.9 +/- 1.2 mm, p<0.05), on the day of embryo transfer (10 +/- 1.7 vs. 7.6 +/- 1.4 mm, p<0.05) and 7 days after embryo transfer (12.2 +/- 0.4 vs. 9.0 +/- 3.0 mm, p<0.05). Estradiol levels in the letrozole group were significantly lower than in the CC group on the beta-hCG day (231 +/- 132 vs. 515 +/- 363 pg/L, p<0.05). Pregnancy was not achieved in either group.
Endometrial thickness is improved by letrozole as compared to CC in frozen-thawed embryo transfer cycles. Further investigation is needed to assess pregnancy and implantation rates.
Available from: William L Ledger
[Show abstract] [Hide abstract]
ABSTRACT: Aromatase inhibitors (AIs) were originally developed for the treatment of advanced breast cancer in postmenopausal women. Their use in reproductive medicine has been extensively studied in the past decade. We reviewed the current strategies for ovulation induction for anovulatory women, mostly women with polycystic ovarian syndrome (PCOS), and the scientific basis for use of AIs in reproductive medicine. The AI, letrozole, is effective in ovulation induction in women with PCOS resistant to clomifene citrate and ovarian stimulation for intrauterine insemination and in vitro fertilization (IVF). Letrozole is an attractive option with its oral route of administration, cost, safety profile and effectiveness in ovulation induction and ovarian stimulation. Letrozole has the potential to be the first-line treatment option for ovulation induction in PCOS women, while its use in ovarian stimulation for IVF deserves further study.
[Show abstract] [Hide abstract]
ABSTRACT: The objective of this article was to review and synthesize information from the scientific literature pertaining to the preparation of endometrium for cryopreserved embryo transfer. This article is a critical review of selected scientific literature, synthesis, and formulation of opinion. Estrogen and progesterone are necessary and sufficient to induce endometrial receptivity in cryopreserved embryo transfer cycles. A variety of regimens have been described including natural cycles using endogenous ovarian hormones and artificial or programmed cycles with exogenously administered steroid hormones. To achieve optimal synchrony between embryo and endometrium, the timing of progesterone administration needs to be adjusted to the developmental stage of the thawed embryos. There is currently no evidence that any single regimen or adjuvant substance results in superior outcomes in cryopreserved embryo transfer cycles, although timing of progesterone administration does matter. Although no single regimen of endometrial preparation for cryopreserved embryo transfer has been proven superior to the others, the relative convenience and ease of use do vary, depending on the route of administration chosen and any adjuvant added to the cycle.
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.