UPA and LNG, what women need to know about emergency contraception

By Cristiano Antonino On Mar 15, 2023

Let’s start with an important clarification: emergency contraception should not be confused with the abortion pill (RU 486) for two reasons, the first that RU 486 is not on sale in pharmacies, it is only a hospital practice, the second that emergency contraception it does not interrupt a pregnancy, but it prevents it

Features of emergency contraception pills

The names that have the two drugs used for oral emergency contraception authorized in Italy, i.e. “five-day-after pill”, for ulipristal acetate (UPA), and “morning-after pill”, for levonorgestrel (LNG) could derive misleading and suggest that the two drugs may have the same efficacy if taken within 120 or 72 hours respectively of unprotected sexual intercourse for various causes.

In reality, both drugs must be taken as soon as possible, to be able to delay ovulation in the most effective way.

The misunderstanding could arise from the fact that ulipristal acetate (ellaone, evante, etc..) and levonorgestrel (norlevo) have different efficacy.

When given during the late follicular phase, around the LH surge and ovulation:

UPA (5 days after pill) is able to delay ovulation for at least 5 days in 59% of cycles
while LNG (morning-after pill) is no different than placebo in inhibiting follicle rupture (ovulation) at this late stage of the ovarian cycle.

And the average time from treatment to follicle rupture is six days, with ulipristal acetate, compared to two days, with levonorgestrel.

But since ovulation is an unpredictable phenomenon, even in women with regular cycles, it is difficult to predict when the woman is most at risk of experiencing an unwanted pregnancy after unprotected intercourse and for this reason it is important to take contraception d oral emergency as soon as possible.

Also because, neither of the two contraceptive treatments is effective when administered on the day of the luteinizing hormone peak, which leads to ovulation.

The safety profile of UPA is comparable to LNG, with mainly mild adverse events.

How effective are emergency contraception methods?

As far as efficacy is concerned, GLASIER et al., highlighted that UPA is able to approximately halve the risk of experiencing an unwanted pregnancy compared to LNG within 120 hours of unprotected intercourse,

These findings therefore led the researchers to recommend that healthcare professionals, who may be tempted to prescribe Ulipristal acetate (UPA) only to women presenting within 72 hours of unprotected sex and those at greatest risk of pregnancy, provide however, ulipristal acetate is always the most effective method, also because women may not be sure of the moment of the menstrual cycle in which they had unprotected intercourse.