What is The Important Link Between Body Weight and Emergency Contraception Solutions?

Emergency contraception pills (ECPs) are readily available in drug stores and trusted pharmacies without a prescription. These pills help women in preventing pregnancies after unprotected sex.

Emergency contraceptives come in two distinct forms:

As a Pill

Emergency pills can either contain ulipristal acetate or levonorgestrel. These are the most commonly used. They are highly effective in preventing pregnancies if taken within 24- 72 hours after unprotected sex.

Combined oral contraceptive pills also fall under this category. Also referred to as “the pill,” combined oral contraceptives contain estrogen and progestogen. They work by delaying the release of an egg from the ovary.

In Form of IUDs

IUDs can help stop you from getting pregnant up to 5 days after unprotected sex. You will need to visit a health practitioner to insert the IUD.

It is essential to take the contraceptives within the stipulated time. Most oral emergency contraception works best when taken within 24 hours of having unprotected sex.

However, studies show that body weight may interfere with the effectiveness of emergency contraceptives. We look at what this means for women in different weight categories and alternatives to emergency pills.

Does Weight Affect Emergency Contraceptive Pills?

Peer-reviewed studies show a drop in the efficacy of levonorgestrel emergency contraception with increased body weight.

These studies show that plan B may not work well for women over a certain weight. For a progestin-only pill such as Plan B and Next Choice, the weight limit is about 155 pounds and a BMI of 30.

Additionally, Ella, the only morning-after pill containing ulipristal acetate, may not be effective in women who weigh 195 pounds or more.

There isn’t enough research on the optimal body weight and BMI limit for ECPs or the rate of pregnancy risk for overweight women. More research is needed to determine how extra weight affects the working of emergency pills.

The Food and Drug Administration (FDA) advises women to take emergency contraception regardless of weight. The most crucial factor is taking the drugs as prescribed and within the time limit.

Why is Plan B Less Effective in Overweight Women?

Information has been scarce regarding why weight affects the effectiveness of emergency birth control.

Some research suggests that the efficacy of the pills could be lower because the active ingredients are diluted when in a larger blood volume. Other suggestions point to a possible difference in how the drug is metabolized in the presence of higher fat content.

Additionally, the pills work by delaying ovulation for 5 to 7 days, at which time any sperm in the womb will be dead. They utilize levonorgestrel, a synthetic hormone that mimics progesterone.

Progesterone occurs naturally in the body and delays ovulation by blocking the production of LH, or luteinizing hormone. LH is responsible for the release of the egg from the ovary.

In women with a BMI of 30 or higher, the synthetic hormone levels from ECPs are lower than is effective in stopping the egg from being released. This could contribute to the lower efficacy of these drugs in women with higher BMIs.

Unfortunately, there still isn’t enough data to make an informed conclusion. What is quite clear, however, is that weight should be a consideration when choosing contraception.

Women should consult their healthcare providers about emergency contraception and what may work best for them.

Should Higher BMI Women Take Higher Doses of ECPs?

Concerned women may choose to take a higher dose of the morning-after pill. The most frequently asked question is whether overweight women should take two Plan B pills.

This is not advisable because it is safe to take Plan B pills regardless of weight. Regular Plan B pill dosages will still reduce the risk of pregnancy in overweight or obese women. Furthermore, other alternatives are available that do not have a weight limit for usage.

The Best Emergency Contraception for Overweight Women

The risk of pregnancy, even with emergency contraceptive use, may be concerning for women with high BMI and body weight. A positive pregnancy test may not always be the intended result of unprotected sex.

Luckily, there are alternative ECs suited for overweight women. These do not get affected by increased weight or high BMIs. Here are some of the best recommendations from wellness professionals:

1. Copper Intrauterine Device, IU.

The copper intrauterine device, IUD, is the most effective method to prevent pregnancy for obese women.

A health practitioner can insert Copper IUDs 120 hours after unprotected sex. Additionally, IUDs keep working to prevent pregnancy for as long as they are in use, up to 10 years.

This method works by releasing copper into the womb, making it harder for sperm to fertilize the egg.

There have not been any reports on higher weight and BMI affecting the copper IUDs. Additionally, IUDs also serve as long-term contraception. However, it is good to note that IUDs are not without some limiting factors. Some of these include;

  1. Irregular menstrual cycle.
  2. Spotting between periods
  3. Worse symptoms of premenstrual syndrome
  4. They require an appointment, which may not be suitable for women in need of emergency contraception.


Another option is Ella. This pill contains ulipristal acetate, which prevents the production of progesterone. Progesterone is responsible for fertilization. Ella is only used for prevention and cannot terminate a pregnancy.

In randomized trials, Ella had a 50% lower overall pregnancy rate in overweight women than levonorgestrel or other plan B pills. Planned Parenthood recommends Ella for women who weigh up to 195 pounds and have a Body Mass Index (BMI) of 30.

Combination Birth Control

Combination birth control pills are taken through oral administration and use synthetic progestin and estrogen to prevent pregnancy.

Combination birth control has proven effective in reducing pregnancy rates when taken within 72 hours.

These pills are available under the brand names Aviane, Enpresse, Levora, and many more.

There is no upper weight or BMI limit on using combination birth control. It is safe to use for obese women within three days of having sex.

New Research Results on Emergency Contraception Pills (ECPs)

Research is currently ongoing to ascertain why weight affects the working of emergency pills.

One such research suggests doubling the dose of levonorgestrel for higher BMI women. Double dosages in this study raised the levels of the drug in the body of obese women, improving efficiency.

Unfortunately, the study was conducted for a relatively small group of women and cannot be used to approve double dosages for clinical use. More information is required for researchers to confidently recommend double dosing to correct the effects of weight on ECPs.

Prevention is Key

Prevention is the safest way to lower the chances of getting pregnant. There are many methods used for long-term birth control that do not have any weight limitations.

Some of the best methods to prevent pregnancy include the Copper IUD, which can be used for up to 10 years.

Other methods include contraceptive implants. Implants last for up to 3 years. The intrauterine system or IUS can be in use for five years. These methods have a 99% rate in pregnancy prevention.

Women who use these long-term birth control methods need not worry about getting pregnant when they choose to. Fertility levels go back to normal immediately after removal.

At Fort Worth Pharmacy, our dedicated team can help you choose the right emergency pill for your body weight.

Our women’s healthcare experts can advise you on the best long-term contraceptive option and help with prescribing information that is tailored to your specific needs.