Barrier methods of contraception literally block sperm from entering your cervix and causing pregnancy. Barrier methods can be a good choice while breastfeeding because they won't interfere with milk supply.

Male Condoms

Latex condoms are easy to find, relatively inexpensive, and protect against both pregnancy and sexually transmitted infections (STIs), which is important if you or your partner are not monogamous or have recently been with other partners. When they are used correctly every time, about three percent of women using them will become pregnant in a year. When your vaginal tissues are still tender, you may find that certain types of condoms — like the ribbed variety — create too much friction and are uncomfortable. You'll want to be sure to use plenty of water-based lubricant if you are experiencing uncomfortable dryness or friction with condoms. Some women are sensitive to latex or the spermicides used on some condoms, which can lead to itching, burning, and redness. If you or your partner is allergic or sensitive to latex, you can try a condom made of polyurethane.

Female Condoms

The female condom, also called the vaginal contraceptive pouch, is a relatively new option. It's a sheath inserted into the woman, lining the entire vagina with polyurethane, and held in place by soft, flexible rings at either end. The female condom is about 95 percent effective, meaning that when used correctly, about five women out of 100 will become pregnant in a year. Since it covers not only the entire inside of the vagina but also the vaginal opening, it can also protect against STIs. You can use an oil-based lubricant with the female condom, since it won't affect the polyurethane, but you shouldn't use female and male condoms together. The friction can cause the male condom to come off, or the female condom to slip to the side or tear. Female condoms are more expensive than male condoms and may be more difficult to find. Inserting and using the female condom may take some practice, and you might find that the ring that fits close to your cervix causes some irritation.

Diaphragm

The diaphragm is a small rubber or silicone device shaped like a dome, filled with spermicidal jelly or cream, and then inserted into the vagina, blocking the cervix, before sex. The spermicide is used to kill any sperm that may work their way in around the rim. Though certain cervical infections such as gonorrhea, chlamydia, or HPV are less likely to be transmitted if you're using a diaphragm, this method isn't considered effective protection against STIs.

Sometimes, you can get a diaphragm at your six-week postpartum visit, but you may have to wait longer if your vaginal muscle tone isn't strong enough yet to ensure a good fit. By three months postpartum, most women have sufficient vaginal muscle tone to use a diaphragm. In the meantime, you can use another form of birth control if you want to resume sex, or you can rely on lactational amenorrhea if you meet the guidelines given previously.

If you're ready to be fitted for a diaphragm, your care provider will perform a pelvic exam to estimate your size, then try several sizes of fitting rings until she finds the one that's the right size for your body. Your care provider can also show you how to use the diaphragm. Since they're available by prescription only, she can either give you one in her office or write you a prescription to pick one up at a pharmacy.

You'll need to buy spermicide that's meant to be used with the diaphragm, but you can find this over the counter, usually near the condoms, in most drugstores. If you or your partner is sensitive to spermicides, the diaphragm isn't a great method for you, since using it without spermicide makes it much less effective.

If you opt to use a diaphragm, you can put it in up to six hours before having sex, and you must leave it in at least six hours after having sex so that the spermicide can kill all the sperm. It can be tricky the first few times you put it in, but most women get the hang of it quickly. The diaphragm may not be for you if you're uncomfortable feeling inside your own body, since you'll need to be able to make sure it's inserted deeply into your vagina and covering your cervix. After a few tries you will become familiar with the way your cervix feels, and it will become easier to tell when the diaphragm is positioned correctly.

If your diaphragm is made of latex rubber, make sure not to use an oil-based lubricant with it like petroleum jelly, baby oil, or mineral oil, since it can weaken the rubber. Water-based lubricants, like KY jelly or mist, are fine. If your diaphragm is made of silicone, you can use any kind of lubricant. You can leave the diaphragm in up to twenty-four hours at a time, but it's better to remove it six to eight hours after having sex. If you leave it in longer, you may risk developing toxic shock syndrome, a rare but very serious illness. You'll also need to regularly check your diaphragm for signs of wear and tear, clean it carefully after each use, and store it away from heat, moisture, and light to make sure the rubber doesn't break down. If you lose or gain a significant amount of weight, have an abortion or miscarriage, or undergo pelvic surgery, you'll have to be refitted for a new diaphragm.

Cervical Cap

In some ways, a cervical cap is very similar to a diaphragm: it works as a barrier method, blocking sperm from reaching your cervix. Your care provider will fit you for it at or after your six-week checkup, then show you how to insert it and care for it. You'll use the cervical cap with spermicidal jelly or cream made specially for use with a cervical cap.

A cervical cap can be inserted up to twenty-four hours before intercourse, allowing for a fair amount of spontaneity. You'll need to leave the cap in place for at least eight hours after sex, but you can leave it in much longer than the diaphragm (up to forty-eight hours). You won't be able to use a cervical cap during your period or if you have a yeast or other vaginal infection. Like with the diaphragm, oil-based lubricants or medications like yeast infection cream can damage the latex. If you're allergic to latex or spermicides, a cervical cap isn't a good option for you.

The cervical cap can get more easily knocked out of place during sex than a diaphragm. And, like the diaphragm, the cervical cap can cause vaginal irritation and increases the risk of urinary tract infection and pelvic infections, including toxic shock syndrome. If you have a cervical cap, you'll need to be refitted every time you have another baby, or if you miscarry or have an abortion.

Spermicides

As the name suggests, spermicides are chemicals that kill sperm. They're available over the counter and come in several forms — cream, jelly, foam, and dissolvable film, with a variety of application methods. They can be used alone or with diaphragms or condoms, which will make them more effective. Spermicides can be messy and may cause irritation.

Used alone, spermicides aren't considered very reliable forms of birth control, but they can greatly increase the effectiveness of other methods, like the male or female condom. Many women and men find that they're sensitive or allergic to spermicides. You may also find that you have a reaction to certain spermicidal products but not to others.

IUD

The intrauterine device, or IUD, is a T-shaped piece of plastic or copper placed inside your uterus by your doctor or midwife. Some IUDs also release the hormone progestin, which makes it more effective at preventing pregnancy. Since the IUD releases the hormone directly into the uterine lining, not much of it gets into your bloodstream, so the IUD may be a good choice for you even if you've disliked the side effects of hormonal contraceptives in the past. You'll want to wait at least six weeks after having a baby before having an IUD placed, since the uterine cramping that happens after giving birth can cause your body to expel the device if it's inserted too early. Also, inserting the hormonal IUD before your milk supply is well established could cause your production to be diminished.