Chances of Getting Pregnant on Birth Control

Birth control pills are one of the most popular forms of contraception. They come in two types: combination pills (containing progesterone and estrogen) and progestin-only pills (containing only progesterone). Because of their popularity, there are numerous brands on the market, such as Sprintec®, Alesse®, or Lutera®.

Consistent use lowers the chances of getting pregnant on birth control pill down to 1%, which means 1 in every 100 women is getting pregnant on while on the pill every year. However, because most women occasionally forget or miss their dose, the realistic odds of pregnancy are higher, about 9 in 100 (9%).

Birth control patches contain estrogen and progesterone, which are absorbed through the skin, where they have to be applied on a weekly basis. The most common birth control patch brands include Xulane® and Ortho Evra®. 

With perfect use, a birth control patch is an effective contraception method (99%). As such, the chances of getting pregnant on the patch are about 1%. Certain factors, such as obesity or current medications, might decrease their effectiveness, while increasing the odds of pregnancy to 9%.

Vaginal rings are self-placed in the vagina for three or four weeks, depending on whether a woman wants to experience periods. The most common brands of vaginal rings include NuvaRing® or Annovera™.

When used as instructed, a woman's chances of getting pregnant on a vaginal ring are 1%. Its effectiveness can be compromised if the ring is not placed in the vagina in a timely manner or if a woman is taking certain medications that interfere with its mechanism of action. As such, the odds of pregnancy increase to 9%.

Birth control shots are administered every three months in a medical facility. The only available brand in the United States is Depo-Provera®, commonly referred to as the Depo shot or DMPA. It is also used in the treatment of endometriosis.

The chances of getting pregnant on Depo shot or other brands of birth control shots are 1% if a woman receives the shot every 12 weeks. Delaying a timely administration increases the odds of getting pregnant to 6%, which means 6 in 100 women do get pregnant on the birth control shot.

Birth control implants are small, rod-like devices that are placed in the arm for up to five years. The brands that offer birth control implants are Implanon® and Nexplanon®.

Birth control implants are considered one of the most effective contraceptive methods. Its placement does not require subsequent administrations for several years, which eliminates the risk of forgetting and other human errors. Consequently, the chances of getting pregnant on the implant are less than 1 in 100 women (1%).

IUD is a T-shaped device placed in the uterus. There are two types of IUDs: copper, such as ParaGard®, or hormonal, like Mirena®. Depending on the brand, they provide protection for 3 to 12 years.

An IUD is another highly effective birth control method. Alike birth control implants, once an IUD is placed, they offer continuous contraception without the need for maintenance. As such, the chances of pregnancy with IUD is less than 1%. When used as emergency contraception, a copper IUD is 99.9% effective.

Barrier methods of contraception work by preventing the sperm from reaching the egg. They come in a variety of forms, including condoms, internal condoms, diaphragms, cervical caps, and spermicidal foams, gels, and sponges.

With perfect use, barrier methods can be up to 98% effective, leaving about a 2% chance of conceiving. However, the realistic odds of pregnancy when using barrier methods of birth control are much higher because they have to be used with every intercourse, thus increasing the risk of failure: 

• Male condom: 15 out of 100 women (15%)

• Internal condom: 21 out of 100 women (21%)

• Diaphragm: 12 out of 100 women (12%)

• Cervical cap: 29 out of 100 women (29%)

• Spermicides: 28 out of 100 (28%)

Tubal ligation, colloquially referred to as “having one's tubes tied,” is a surgical procedure to block or close the fallopian tubes so that the sperm cannot reach the egg for fertilization.

Most are permanent, resulting in less than a 0.5% chance of getting pregnant after tubal ligation. However, some women might undergo a tubal ligation reversal to achieve pregnancy or relieve post-procedure side effects.

Contraception is of great help when pregnancy is not desired at all or is meant to be delayed for the future. Popular claims about their alleged effectiveness often make women wonder what their chances of getting pregnant on birth control are. The answer to these doubts are two-factorial: it depends on the type of contraceptive method used and how diligently a woman adheres to its recommended usage. Perfect use puts women at a 1% chance of pregnancy while on birth control. However, most women do not adhere to the schedule perfectly, thus lowering their effectiveness and increasing the odds of conception. As such, typical use results in higher pregnancy rates, ranging from 6 – 9 in 100 with pills, rings, patches, and shots to up to 29 in 100 with barrier methods of birth control, like condoms or diaphragms.