This review concludes that there is insufficient evidence to support the use of one menstrual cycle regimen over another in frozen-thawed embryo transfer (FET).

Ghobara T, Vanderkerchove P

Published Online:

November 10, 2010

Women with regular spontaneous cycles may be offered any of the cycle regimens to prepare the womb lining for FET. If artificial cycles are used there is some evidence to support the use of an additional drug that suppresses hormone production by the ovaries (gonadotrophin releasing hormone agonist (GnRHa)). There is a need for additional well-designed studies to be performed, to determine whether a specific cycle regimen is linked with higher pregnancy and live birth rates.

Abstract (click to read)

Background:

Pregnancy rates following frozen-thawed embryo transfer (FET) treatment have always been found to be lower than following embryo transfer using fresh embryos. Nevertheless, FET increases the (cumulative) pregnancy rate, reduces cost, is relatively simple to undertake and can be accomplished in a shorter time period compared to repeated 'fresh' cycles. FET is performed using different cycle regimens: spontaneous ovulatory cycles, cycles in which ovulation is induced by drugs and cycles in which the endometrium is artificially prepared by oestrogen (O) and progesterone (P) hormones, with or without a gonadotrophin releasing hormone agonist (GnRHa).

Objectives:

To determine whether there is a difference in outcome between natural cycle FET, artificial cycle FET and ovulation induction cycle FET.

Search strategy:

Our search included CENTRAL,DARE, MEDLINE (1950 to 2007), EMBASE (1980 to 2007) and CINAHL (1982 to 2007).

Selection criteria:

Randomised controlled trials (RCTs) comparing the various cycle regimens and different methods used to prepare the endometrium during FET in assisted reproductive technology (ART).

Data collection and analysis:

The two authors independently extracted data. Dichotomous outcomes results (e.g. clinical pregnancy rate) were expressed as an odds ratio (OR) with 95% confidence intervals (CI) for each study. Continuous outcome results (endometrial thickness) were expressed as weighted mean difference (WMD). Where suitable, results were combined for meta-analysis with RevMan software using the Peto-modified Mantel-Haenszel method.

Main results:

Seven randomised controlled studies assessing six comparisons and including 1120 women in total were included in this review.

1) O + P FET versus natural cycle FET: this comparison demonstrated no significant differences in outcomes but confidence intervals remain wide, and therefore moderate differences in either direction remain possible (OR 1.06, 95% CI 0.40 to 2.80, P 0.91).
2) GnRHa plus day O plus day P FET versus O plus day P FET: this comparison showed that the live birth rate per woman was significantly higher in the former group (OR 0.38, 95% CI 0.17 to 0.84, P 0.02). The clinical pregnancy rate was also higher but not significantly so (OR 0.76, 95% CI 0.52 to 1.10, P 0.14).
3) O plus day P FET versus follicle stimulating hormone (FSH) FET, 4) O plus day P FET versus clomiphene FET and 5) GnRHa plus day O plus day P FET versus clomiphene FET: there were no differences in the outcomes in the comparison of these cycle regimens.
6) Clomiphene plus day human menopausal gonadotrophin (HMG) FET versus HMG FET: in a comparison of two ovulation induction regimes the pregnancy rate was found to be significantly higher in the HMG group (OR 0.46, 95% CI 0.23 to 0.92). There were also fewer cycle cancellations and a lower multiple pregnancy rate when HMG was used without clomiphene but these did not reach statistical significance.

Authors' conclusions:

At the present time there is insufficient evidence to support the use of one intervention in preference to another.

This record should be cited as:

Ghobara T, Vanderkerchove P. Cycle regimens for frozen-thawed embryo transfer. Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD003414. DOI: 10.1002/14651858.CD003414.pub2

Assessed as up to date:

October 11, 2007

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Primary Review Group:

Menstrual Disorders and Subfertility Group

Health topics:

Gynaecology > Subfertility > Female: assisted conception techniques

Cochrane Summaries^beta

Independent high-quality evidence for health care decision making

This review concludes that there is insufficient evidence to support the use of one menstrual cycle regimen over another in frozen-thawed embryo transfer (FET).

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