Transdermal vs. vaginal estrogen: which is more effective for uterus preparation?

This study investigated the optimal route for estrogen administration to increase endometrial thickness (EMT) in women undergoing assisted reproduction (AR).

They found that transdermal (on the skin) estrogen (TE) was associated with higher EMT and better patient satisfaction compared to vaginal estrogen (VE). 

Endometrial preparation is an important step in assisted reproduction (AR). The endometrium (EM) is the lining of the uterus. The EM is where embryos implant and grow. For the embryo to be implanted, the EM needs to be of a certain thickness. After in vitro fertilization (IVF) embryos may be transferred fresh or frozen.  A combination of drugs is given to prepare the EM before frozen embryo transfer (FzET). 

There are many ways to stimulate the EM for implantation. EM preparation usually involves administering estrogen and progesterone. Estrogen can be taken in several ways. It can be delivered using a transdermal (skin) patch (TE). It can also be administered directly in the vagina (VE). It is unclear if there is a difference in the effects of TE and VE on endometrial thickness (EMT). 

This study included 215 patients. These women underwent 318 AR cycles. Women were treated with TE or VE, as they chose. Progesterone was also administered. EMT was measured using ultrasound. FzET was performed when EMT was more than or equal to 8 mm. Outcomes measured were clinical pregnancy rate (CPR) and live birth rate (LBR). Patients were also asked to report their satisfaction with treatment. 

EMT was significantly higher in the TE group. Patients in the TE group had a shorter treatment duration. Spontaneous ovulation was more common with TE. There were no differences in pregnancy outcomes between the 2 groups. Satisfaction scores were higher in women treated with TE. 

The authors concluded that transdermal estrogen was associated with higher endometrial thickness and satisfaction in women undergoing IVF.

Patients were not randomly assigned to treatment. This could skew the results. The number of patients in this study could be considered low. A randomized study may be needed. 

If you have any concerns regarding infertility management please consult your physician.