PORTLAND, Ore. (KOIN) – Researchers have found that emergency contraceptives, commonly known as Plan B or the morning-after pill, are less effective for people with a higher body mass index. One hypothesized solution to the problem was to double the dose of the Plan B pill, but scientists at OHSU recently discovered this is not effective.
Previous research has shown that people with a BMI, or a measurement of height-to-weight ratio, of 30 experienced a failure of the morning after pill four times as often as those with a BMI of less than 25.
Scientists at OHSU wanted to know if the simple solution of doubling the morning after pill dose would improve outcomes. Their study, which was recently published in the journal “Obstetrics & Gynecology” found it does not.
“Emergency contraception is a critical therapy for our patients. We need to ensure that it works effectively for everyone no matter their BMI or weight,” said lead author Dr. Alison Edelman, professor of obstetrics and gynecology in the OHSU School of Medicine.
Emergency contraception can prevent pregnancy when taken as soon as possible after intercource and pills like Plan B are usually readily available, since they’re available over-the-counter without a prescription.
The pill prevents pregnancy by delaying or hindering ovulation using the medicine levonorgestrel, or LNG. LNG rapidly reaches its peak level at a critical point before the body gives the signal to cause ovulation. Edelman’s prior research shows that LNG blood levels were 50% lower in people who had a BMI of 30 after taking a standard dose of the morning-after pill.
This means LNG never reaches its peak level and therefore likely fails to prevent ovulation.
To test the double-pill hypothesis, Edelman conducted a study among 70 healthy, reproductive-age people with regular menstrual cycles, BMIs higher than 30 and weights of at least 176 pounds.
The researchers measured how many participants experienced a delay or inhibition of ovulation when taking the regular dose of emergency contraception compared to the double dose.
The results showed no difference in the effectiveness of one pill versus two.
Edelman said this discovery will help guide researchers to find the most effective strategy to provide emergency contraceptives to people with higher BMIs.