What is the birth control pill and what is an IUD? Learn about things to consider when choosing between the two and other contraception options. When deciding between using a birth control pill or IUD, there are a few important factors to consider. Some contraception options are better for certain people, and switching between them takes care. With over 20 percent of women ages 15-44 in the United States alone using contraception, it is important to understand how to use it properly. Read on to discover what contraceptive method is right for you. What is the birth control pill and how does it work? Birth control pills are a type of medication that women take on a regular basis to prevent pregnancy. The birth control pill is often called "the pill," and a doctor may call it an oral contraception pill. The birth control pill works by stopping eggs from leaving the ovaries. Birth control pills use hormones to prevent pregnancy. Hormones are a type of chemical made in the body that changes how different parts of the body work. Changing the hormone levels in the body creates changes in the body itself. The two hormones used most in birth control are estrogen and progestin. Estrogen is the natural hormone made in a woman's ovaries. Progestin is a synthetic form of progesterone, which is known as "the pregnancy hormone." Birth control pills typically contain both the hormones estrogen and progestin. Some are made with only progestin, but these are usually used only when women are breastfeeding. When a woman takes the pill, these hormones cause two main changes in her ovaries. The hormones work to keep the woman's eggs from leaving her ovaries during ovulation. A pregnancy cannot happen if the woman does not ovulate. The second role of the pill is to thicken the mucus in the woman's cervix to prevent sperm from reaching her eggs.

What is an IUD and how does it work?

IUD stands for intrauterine device. An IUD is a small device typically made of plastic, which releases either copper or a form of progestin into the uterus.

The design of the device can vary, but most IUDs have one or two threads on the end of them. When the device is fitted to the woman's uterus, these threads will hang through the opening at the entrance of the cervix.

An IUD works by keeping the sperm from reaching an egg. It thickens the mucus in the cervix, which prevents sperm from getting through to the uterus. IUDs also make it difficult for eggs to stick to the lining of the uterus, preventing implantation.

Choosing between an IUD and the pill

While both an IUD and birth control pills will help prevent unwanted pregnancies, there are many differences between the two that people should take into consideration.

An IUD contraceptive
IUDs are an effective form of contraception but may have similar side effects to the birth control pill.


When used perfectly, the pill is a highly effective way to prevent unwanted pregnancy, with a failure rate of around 0.1 percent.

When used incorrectly, however, women are much more likely to get pregnant. It is estimated that around 8 of every 100 women who use birth control pills will get pregnant, and this may be due to improper use of the pill.

IUDs are a highly effective form of birth control. Copper-releasing IUDs have a remarkably low failure rate of less than 1 per 100 women in the first year of use. This remains rather stable at 98-99 percent effective over 5 years of use and can last for up to 10 years.

Side effects and risk factors

Though the pill is effective when used correctly, there are some side effects to consider when choosing to use it. Side effects of birth control pills include:

  • Bleeding between periods

  • Nausea and vomiting

  • Breast tenderness

  • Headaches

  • Genital irritation

  • Tiredness

  • Bloating

  • Menstrual pain.

Many side effects clear up with most women after the first few months of use.

All women, especially those over the age of 35, should be screened for vascular disease before starting oral contraception. This is because birth control pills can increase the risk of vascular diseases such as heart attack and stroke. They can also increase the risk of blood clots, liver tumors, and gallstones.

Other factors that may increase this risk are high blood pressure, smoking, and metabolic syndrome.

Rare but serious side effects can occur, which is why it is important to regularly check in with a doctor to see how the body is responding to the medication.

IUDs can have some similar side effects to birth control pills, though they are less common. Side effects of IUDs include:

  • Cramps

  • Nausea

  • Bloating

  • Backache

  • Inflammation of the vagina

  • Vaginal discharge.

Rare but serious side effects can also occur with IUDs. These include eggs implanting outside of the womb and serious infections. Women using IUDs have a greater risk for pelvic infection within the first few weeks of using an IUD. Regular doctor visits can help check for signs of infection.

IUDs may also slip out of place. This is most common during the first 3 months of use. Women should never try to put an IUD back into place on their own. They should consult a doctor as soon as possible to reinsert the device.

A highly unlikely risk of the IUD tearing the uterus or cervix is also present. This may cause pain, but often there are no symptoms. In rare cases, the IUD must be removed surgically.

Duration of use

In order for birth control pills to be effective, the woman must remember to take a pill every day of their 21- or 28-day cycle. This is part of the reason the pill has varied results; many women forget to take the pill or forget to restart the pill cycle.

Once an IUD is inserted, it can remain effective for up to 10 years. Other than regular checkups to ensure it is in place and the body is responding well to it, IUDs are a safely forgotten form of contraception.


The pill can cost anywhere from $0 to $50 for each month of coverage, depending on the woman's insurance coverage.

An IUD can cost anywhere from $0 to $1,000 depending on insurance coverage. An IUD will also require the cost of regular checkups to ensure it is safely in place.

Special considerations

Doctor and patient
Any questions or concerns about contraception should be discussed with a healthcare professional.

  • Women over the age of 35 would benefit more from an IUD due to the risk factors involved with using the pill

  • Heavy smokers are also advised against using the pill due to the combined risk of vascular disease

  • Women who are sensitive to extra hormones in their body may also benefit from a copper IUD, as they are a non-hormonal contraceptive option

  • IUDs may not work correctly in women with irregular uterine cavities

  • Women prone to infections and women who have copper allergies should also avoid using IUDs. Birth control pills are better options for these groups.

Switching from one option to the other

When switching between contraceptive methods, it is important not to leave a gap in coverage to reduce the chance of becoming pregnant. When switching from an IUD to the pill, women should begin taking the pill 7 days before the IUD is removed.

When switching from the pill to a hormonal IUD, women should insert the IUD 7 days before stopping the pill. When switching from the pill to a copper IUD, the IUD may be inserted up to 5 days after stopping the pill.

Other contraception options

These are just two of the many contraception options out there. The levels of effectiveness and comfort vary based on the method used to avoid pregnancy.

Other contraception methods include:

  • Condoms

  • Progestin implants

  • Progestin shots

  • Vaginal rings

  • Cervical caps

  • Hormonal patches

  • Diaphragms

  • Sponges

  • Abstinence

  • Fertility awareness

  • Permanent sterilization.

The important considerations above will come into play when choosing any contraceptive method.

Written by Jon Johnson