Evaluation of Exogenous Estrogen on IUI Success Rates

Abstract

Research Question: The research question that drove our research was the following: What effect does estrogen supplementation during the ovulation cycle have on pregnancy outcomes compared to patients not receiving estrogen supplementation in women younger than 35 years of age and women aged 35-39 years who desired to conceive via IUI? By determining the effects of exogenous estrogen supplementation on pregnancy success rates, the utility of IUI may be increased as success rates may improve. This would further improve clinical pregnancy success rates for patients without cost acting as a significant burden.

Background and Significance: Patients are often deterred from in vitro fertilization (IVF) for contraception assistance due to the cost and turn towards intrauterine insemination (IUI) before attempting IVF. However, for patients under the age of 35, IUI success rates are lower compared to IVF. It is hypothesized that this may be partly due to too thin of an endometrium. Data has demonstrated that a thin endometrial lining, defined as less than 7 mm, has less favorable outcomes in fertility treatments, especially with IVF. The effects of estrogen supplementation on pregnancy outcomes in relation to thin endometrial thickness have not been as thoroughly evaluated in IUI cycles. Additionally, the common practice of rescuing the endometrium with exogenous estrogen has not been adequately studied.

Materials and Methods: 200 patients who underwent IUI between January 19 and September 22 were randomly selected from two categories: patients who utilized estrogen supplementation and controls (ie. no supplementation). Inclusion criteria included normal semen analysis (SA), two patent fallopian tubes, and patients under the age of 40 (stratified into <35 & 35-39). Exclusion criteria include male factor, defined as less than or equal to 5 million motile sperm, BMI greater than 35, smokers, and diminished ovarian reserve (DOR) defined by an anti-Mullerian hormone (AMH) level less than 1. Successful pregnancy was defined as a heartbeat detected (via vaginal ultrasound) at 6.5-7 weeks. For the experimental group, Estrace 2 mg was added (twice per day orally or once per day vaginally) at the initial ultrasound to start the fertility medications or at the follow up ultrasound during the treatment cycle to continue until a heartbeat was detected or a negative pregnancy test resulted. After assessing the normality of distribution of our data, we analyzed the data using an unpaired, two-sample t-test to determine whether estrogen supplementation improved the pregnancy rate associated with IUI.

Results: While we initially anticipated that administering estrogen during an IUI cycle when the endometrium was considered thin would improve clinical pregnancy rates, this research surprisingly found that pregnancy rates were not impacted by exogenous estrogen.

Conclusion: We understand that this is just one study and that we are limited by a small sample size. However, given the results of this research, it may be appropriate to discontinue the use of exogenous estrogen in this patient population. Continuing to utilize this treatment without success may prove fruitless and cost inefficient. This study should prompt additional research with greater sample sizes to further enhance the value of our findings, and if similar findings our discovered, standards should be updated to refrain from utilizing supplemental estrogen with the aspirations of improving clinical pregnancy rates from IUI.