My period is late this month, so I took a pregnancy test at home. Thankfully, it was negative. But I’m still really anxious—is there any chance I’m pregnant even though the test was negative?

First, it’s great that you took a pregnancy test! A lot of people get so scared about the possibility of being pregnant that they put off taking a test. This not only leaves them in a state of anxiety, but means that they have fewer options if they are actually pregnant.

The good news is that home pregnancy tests are very accurate if taken at least a week after your missed period, and there are lots of reasons that your period may be late. The length of a menstrual cycle can change from month to month, especially in teenagers. It’s actually MORE common to have an irregular cycle than to have your period arrive like clockwork. Periods can also be late because of an illness, stress, or changes in your weight, medication, eating habits, or physical activity.

HOWEVER, it is possible for a pregnancy test to say you’re not pregnant when you really are.

Pregnancy tests measure the amount of human chorionic gonadotropin (hCG) in your blood or urine. If you’re pregnant (meaning a fertilized egg has implanted on the wall of your uterus, which usually occurs 5-6 days AFTER fertilization), your body will almost immediately start producing hCG. The amount of hCG in your body doubles every 2 to 3 days after you become pregnant.

If you’ve only just become pregnant, there may not be enough hCG in your urine for the pregnancy test to detect it. Because of this, it’s best to wait at least a week after your period usually starts to take a pregnancy test. The results will be more accurate if you take the test in the morning, when your urine is more concentrated. Make sure you follow the directions on the pregnancy test very carefully, and check the expiration date.

The good news is that if you took the test at least a week after your missed period, there is a 99% chance that you are not pregnant. If you still feel anxious, or your period still doesn’t arrive after 10 days, make an appointment with your health care provider. They can give you a more accurate pregnancy test, figure out if something is messing with your menstrual cycle, and help find the best method of birth control for you. They can also answer any questions you have about your pregnancy risk, STI testing, and how to be sexually healthy. If you’re 10-22 years old and live near NYC, you can come to Mount Sinai Adolescent Health Center for a free, confidential and non-judgmental appointment with a healthcare provider.

If you’re already using reliable birth control and still often feel anxious about getting pregnant, you’re not alone. Pregnancy is terrifying to many teens (and adults!), and our sex education system often uses scare tactics that leave teens convinced that they’ll get pregnant if they so much as hold hands with someone else. It may help you to learn about how your birth control works, and what the pregnancy risks are for different sex acts. Take a minute to check in with yourself about how you feel about sex. Do you feel in control when you have sex? Do you talk openly with your partner(s)? Are you enjoying yourself? It’s possible that your anxiety about one part of your sex life is making you anxious about a totally different part.