Clearblue & Natural Cycles Birth Control Kit is hormone-free and 93% effective with typical use[1]. The NC Birth Control app uses an algorithm to identify your fertile days (when you are most likely to get pregnant) based on basal body temperature. Your hormones cause your body temperature to rise after ovulation. This helps to identify where you are in your cycle. Simply measure your temperature when you wake up using the digital basal thermometer included in the starter pack, then add your reading to the NC app. The app calculates your fertility status for that day. Green Days ('Not fertile') mean you can have sex without protection[1]. Red Days ('Use protection') indicate you are likely to be fertile and at risk of getting pregnant. On Red Days you should use protection (such as condoms) or abstain from having sex to avoid pregnancy. If you're using this method, it's important you feel comfortable doing this and that you understand it does require a routine, including taking your temperature in the morning. Measuring your temperature once a day, on as many days as possible, allows the algorithm to quickly get to know your cycle. Aim to measure your temperature at least 5 days a week. On the days you use a Clearblue Digital Ovulation Test, add the result to the NC app. Clearblue Digital Ovulation Tests (15 tests and a digital holder also included in the starter pack) identify the surge in luteinizing hormone which happens 24-36 hours before ovulation, to pinpoint your most fertile days. Clearblue Digital Ovulation Tests are also sold separately as a refill pack (with holder). [1] Natural Cycles is 93% effective with typical use which means if 100 women use this method for 1 year, we expect 7 will become pregnant. Typical use includes all unintended pregnancies, such as due to having unprotected sex or using withdrawal on a Red Day, as well as pregnancies that occur while the method is used as intended. STARTER KIT CONTAINS: 3-MONTH subscription to the Natural Cycles birth control app, 15 Clearblue Digital Ovulation Tests, 1 Digital Basal Thermometer, 1 Clearblue Reader FDA-CLEARED, HORMONE-FREE BIRTH CONTROL APP: Natural Cycles is an FDA-cleared, non-hormonal, non-invasive birth control method which helps you manage your fertility BIRTH CONTROL WITHOUT HORMONAL SIDE EFFECTS: No side effects with Hormone-Free Birth Control. Helps to manage your fertility on your terms, with tools designed to fit your lifestyle TAKE CONTROL OF YOUR CYCLE: The NC algorithm uses your temperature to pinpoint your fertile days to help you prevent pregnancy 93% EFFECTIVE: Natural Cycles is clinically proven to be 93% effective with typical use (1). Other than abstinence, no method of birth control is 100% effective BACKED BY SCIENCE: The NC algorithm uses basal body temperature (BBT) to identify fertile and non-fertile days and to confirm ovulation. Taking ovulation tests is optional and can help the NC algorithm predict your ovulation day IDENTIFY THE MOST FERTILE DAYS: Use Clearblue Digital Ovulation Tests to identify the surge in luteinizing hormone (LH). This happens 24-36 hours before ovulation to identify your 2 most fertile days Directions: Testing Strips