In the U.S., half of all pregnancies are unintended. Yet contraceptives have effectiveness rates that range from nearly 100 percent to about 70 percent, depending on the chosen method.

Nearly 99 percent of women aged 15 to 44 have used a birth-control method at least once. Sixty-two percent of all women of reproductive age currently use contraceptives. And 11 percent of women who are at risk of pregnancy don’t use any birth control at all. The pill and sterilization are the two most common forms of contraceptives since 1982.

Then there are those incidences where birth control’s efficacy is eroded due to certain situations. The following are common mistakes women and men make while trying to prevent pregnancy.

• When first starting on a hormone-based oral contraceptive, some doctors recommend that you use another form of contraceptive such as condoms for a month after starting the pill.
• If you use the most commonly prescribed combination of hormonal contraceptives – estrogen and progestin pills – did you know that missing three or more days will get you in trouble if you don’t address the situation correctly? You are OK to restart pills after missing a couple of doses, but for the first seven days, it is highly recommended that you use another form of birth control, like condoms, because the pill may not be effective.
• If you forget to take the pill for a day, take two pills the next day. If you miss two days, take two pills for the next two days. You will be back on schedule. If you miss more than two days, see above.  
• Progestin-only pills have to be taken at the same time of day every day. With this pill, if you take the pill even three hours late, you must use another form of birth control for the next 48 hours.
  

• If you have a birth control implant, like Depo-Provera, or start taking combination pills within five days of your period, you don’t need birth control backup. But start at any other time, and you need another birth control method for the next seven days. For progestin-only pills, backup is needed for the first 48 hours of use.
• Illnesses like the flu that involve vomiting or diarrhea can lower the efficacy of birth control pills. Use another method of birth control for seven days after the illness passes. Do this even though you may not have missed taking any pills.
• If you are a smoker and a woman older than 35, birth control pills aren’t recommended for you. This is especially true if you have any of the following conditions: a family or personal history of blood clots, migraines with aura, cancer of the breast or uterus, heart or liver disease, or uncontrolled high blood pressure. Find another method of birth control that will be less damaging to your health.
• To continue the subject, make sure you are on the correct kind of contraceptive. If you can’t take estrogen because of migraines, breastfeeding, heart disease or other conditions, there is the progestin-only pill as an alternative. But one should be reminded that the combination pill is more effective.
• Other options should be explored if taking a daily pill is a hassle, or you are forgetful. There are birth control injections that are effective for three months; the same goes for vaginal rings, patches and diaphragms. But the last three involve a bit more maintenance than a shot or implant.
• Don’t use the antibiotic Rifampin if you take the combination pill because it undermines hormone-based contraception. It is also the same for the patch or vaginal ring.
• Other drugs that can be problematic for those on hormonal contraceptives are some anticonvulsants, antibiotics, HIV drugs or oral medications for yeast infections. Check with your doctor or pharmacist for drug interactions.
• Can there be a “wrong” condom to use? There is emerging evidence that polyurethane condoms break more frequently than latex. Though they are considered effective in preventing pregnancy, lambskin condoms shouldn’t be relied on for STD prevention. The tiny pores in these condoms are small enough not to allow sperm to pass through, but other bodily fluids may penetrate them.
  

• Use condoms correctly. They are 98 percent effective when used correctly. This is no time for vanity – select the right size for maximum safety. When applying, to prevent breakage, squeeze the air out of the tip. Unroll it the correct way. If you find that you have incorrectly applied the condom, discard it and start anew.
• Use the right lubricant. Oil or oil-based lubricants like baby oil and mineral-oil body lotions or Vaseline can weaken a latex condom in 60 seconds. To prevent this, use water-based or silicone-based lubricants. Keep in mind that many lipsticks contain oils that also can weaken a condom.
• Did you know that condoms have expiration dates? Check them and discard outdated ones. They aren’t very expensive, and the risk is not worth a few bucks. Condoms also lose efficacy when exposed to heat. Guys, the worst place for them is in your wallet. Being cramped in a wallet and shoved into a pocket next to your nice, warm body can damage or weaken the condom.
• Properly store the vaginal ring, Nuva Ring, at room temperature or in the refrigerator. At room temperature, the ring should last three or four months. If stored in the fridge, it will last until the expiration date. But if it was stored someplace very warm, like near a heating unit, throw it away and get a new one.
• If your contraceptive sponge was nicked or torn during insertion, efficacy is lowered. You may want to use one that is not damaged. The same concerns apply to condom wrappers.

• Are you ready with an emergency plan in case of unplanned and unprotected sex? Have the “morning-after” pill, also known as Plan B, on hand for those times. People who are 17 or older can purchase the morning-after pill over the counter, no prescription needed. The pill should be taken within three days of unprotected sex, but the sooner, the better. Some experts say morning-after pills are good for up to 120 hours, or five days after sex.

You should now have a pretty good idea of some things to avoid while using various birth control methods. The most important idea with contraceptives is to use them consistently and correctly to avoid unintended pregnancies. If you have questions, talk to your health care professional and don’t be shy. There isn’t much they haven’t heard before, and they can be very helpful.