Birth control pills use low doses of hormones to prevent ovulation 排卵 and thicken the mucus on the cervix. If there is no egg to fertilize, pregnancy cannot happen. The hormones also thicken the mucus on the cervix 宫颈, making it difficult for sperm to pass through. Learn more here.

Different brands of birth control pills use different combinations and levels of hormones. If you are thinking about starting to take birth control pills for the first time, it's important to talk to a doctor to help decide which type is best for you.

When taken correctly, birth control pills are very effective at preventing pregnancy. Your doctor can tell you the specific effectiveness rate for the brand of pill you choose.

To take birth control pills correctly, you must remember to take a pill every day and some pills need to be taken at the same time each day. Typically you take a pill each day for 21 days, and then take a break (or take a non-active pill) for 7 days during which you will have a period.

If you miss taking a pill one day, you typically need to use a back up method such as condoms for a week after the missed pill.

Each type of pill has specific instructions on the package for what to do if you miss a day. You can also consult with a doctor.

Yes. Birth control pills are safe and effective for long term use and have low doses of hormones that typically don't cause side effects such as weight gain. In fact, many people who take birth control pills also see improvement in acne or skin problems, lighter bleeding during periods, and improvement in PMS symptoms. It is possible to become pregnant soon after stopping birth control pills.

However, some people may experience side effects while taking birth control pills, and people with certain health conditions should avoid taking them. If you are thinking about starting to take birth control pills, it’s best to meet with a doctor first to discuss whether it’s the best method for you, and which brand is recommended to use.

Emergency contraception ("morning after pill" 紧急避孕) is a safe and effective way to prevent pregnancy after unprotected vaginal sex. This includes having sex without a condom or other barrier method, situations where a condom breaks, or other scenarios that may include a risk for pregnancy.

Emergency contraception should be taken as soon as possible after unprotected sex. You can start taking it up to 120 hours (5 days) after the incident, but it is most effective when taken within 72 hours. In Shanghai, you can buy emergency contraception at any pharmacy without a prescription. The Chinese name is 毓婷 (Yu Ting) or 左炔诺孕酮 (zuo que nuo yun tong).

Emergency contraception is safe, but there can be unpleasant side effects such as nausea, vomiting, irregular bleeding, dizziness and headaches. It should not be used an ongoing form of birth control because there are other methods that work more effectively with much lower risk of side effects.

Find out more about how emergency contraception works.