Pregnancy outcomes following different protocols of controlled ovarian hyperstimulation in couples undergoing intrauterine insemination

Clomiphene citrate (CC), letrozole and cetrorelix acetate are frequently used agents in controlled ovarian hyperstimulation (COH). However, these three agents have not yet been compared to one another regarding their pregnancy outcomes. The present study was designed to retrospectively compare pregnancy outcomes among the three aforementioned agents. This study involved infertile couples with an infertility duration of at least 2 years, ages 18 to 42 years and who were referred to have their first intrauterine insemination (IUI) treatment cycle. All patients underwent COH with recombinant follicle-stimulating hormone (rFSH) plus CC (n = 118), letrozole (n = 81), or cetrorelix acetate (n = 62), followed by IUI. Using the one-way multivariate analysis of covariance to control female patients' ages, patients stimulated with cetrorelix acetate/rFSH or CC/rFSH had higher numbers of preovulatory follicles than women stimulated with letrozole/rFSH (P < .02), whereas women stimulated with cetrorelix acetate/rFSH had a thicker endometrium than women stimulated with CC/rFSH (P < .0005). Biochemical pregnancy rates were similar among the three protocols of COH. However, women stimulated with letrozole/rFSH showed clinical pregnancy rates higher than those stimulated with CC/rFSH (P = .003) or cetrorelix acetate/rFSH (P = .03) and subclinical abortion rates lower than those stimulated with CC/rFSH or cetrorelix acetate/rFSH (P = .009). Of the different protocols of COH, the odds of having a clinical pregnancy was 3.1 times greater for women stimulated with letrozole/rFSH than women stimulated with CC/rFSH (P = .004) and 2.8 times greater for women stimulated with letrozole/rFSH than women stimulated with cetrorelix acetate/rFSH (P = .03). Our observations show that increased numbers of preovulatory follicles or endometrium thickness do not necessarily improve pregnancy outcomes, because pregnancy outcomes are also subjected to the type of COH used agent. In this regard, letrozole produced fewer preovulatory follicles and did not significantly increase endometrium thickness, but significantly improved pregnancy outcomes in comparison to CC and cetrorelix acetate.