Pseudopregnancy

High-dose estrogen
Drug class
Estradiol valerate, an estrogen which has been used as a means of HDE.
Class identifiers
Synonyms	Pseudopregnancy (when used in combination with a progestogen)
ATC code	G03C
Biological target	Estrogen receptors (ERα, ERβ, mERs (e.g., GPER, others))
Chemical class	Steroidal; Nonsteroidal

High-dose estrogen (HDE) is a type of hormone therapy in which high doses of estrogens are given. When given in combination with a high dose of a progestogen, it has been referred to as pseudopregnancy. It is called this because the estrogen and progestogen levels achieved are in the range of the very high levels of these hormones that occur during pregnancy. HDE and pseudopregnancy have been used in medicine for a number of hormone-dependent indications, such as breast cancer, prostate cancer, and endometriosis, among others. Both natural or bioidentical estrogens and synthetic estrogens have been used and both oral and parenteral routes may be used.

HDE and/or pseudopregnancy have been used in clinical medicine for the following indications:

The nonsteroidal estrogen diethylstilbestrol as well as other stilbestrols were previously to support pregnancy and reduce the risk of miscarriage, but subsequent research found that diethylstilbestrol was both ineffective and teratogenic.

HDE should be combined with a progestogen in women with an intact uterus as unopposed estrogen, particularly at high dosages/levels, increases the risk of endometrial hyperplasia and endometrial cancer. The majority of women with an intact uterus will develop endometrial hyperplasia within a few years of estrogen treatment even with mere replacement dosages of estrogen if a progestogen is not taken concomitantly. The addition of a progestogen to estrogen nearly abolishes the increase in risk.