Abstract
Background
Ulipristal acetate (UPA) 30 mg (ella®, HRA-Pharma, Paris, France) acts as an emergency
contraceptive (EC) by delaying ovulation. Because it is a selective progesterone receptor
modulator, an additional effect on interfering with implantation has been suggested.
Objective
This review discusses the evidence for, and against, an anti-implantation effect of
UPA-EC.
Sources of evidence
Primary research on the effect of UPA, at a relevant dose, on endometrium, implantation,
efficacy and pregnancy outcome.
Results
UPA-EC does not appear to have a direct effect on the embryo. Changes in endometrial
histology are small and not consistent, varying among studies. While UPA-EC affects
the profile of gene expression in human endometrium, the findings vary between studies,
and it is not clear that these changes affect endometrial receptivity or prevent implantation.
UPA at pharmacological concentrations does not appear to have any inhibitory effect
on embryo attachment in in vitro systems of human endometrium. UPA-EC is not more
effective at preventing pregnancy than chance alone if used after ovulation and does
not increase miscarriage rates.
Conclusions
An anti-implantation effect of UPA is highly unlikely at the dose used for EC. Maintaining
the warning on the FDA-approved label that “it may also work by preventing implantation
to the uterus” might deter some women from using EC, leaving them no option to prevent
unwanted pregnancy after unprotected sexual intercourse.
Keywords
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Article info
Publication history
Published online: July 24, 2019
Accepted:
July 18,
2019
Received in revised form:
July 15,
2019
Received:
March 14,
2019
Footnotes
☆Declaration of interest: M.R.R. is employed by HRA-PHARMA; A.G. and K.G.D. undertake consultancies for HRA-PHARMA; H.W.R.L., I.C.B., K.G.D. and A.G. have all received research support for HRA-PHARMA.
☆☆Funding source: No specific funding was provided for preparation of this manuscript.
Identification
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© 2019 Elsevier Inc. All rights reserved.
