Breastfeeding can inhibit ovulation and is in itself effective protection the first 6 months after birth if you breastfeed full-time (exclusively) and haven't gotten your first period yet. However, ovulation will occur before your first period returns and then the chances of becoming pregnant from unprotected intercourse increase. Also, it's good to keep in mind that ovulation may still occur during the first six months too, this is why pregnancy is possible if you have unprotected intercourse during this time.
We recommend that you start measuring roughly 4-5 months after giving birth while breastfeeding full-time (exclusively), and 1-2 months after giving birth if you do not breastfeed full-time.
Until your first ovulation, therefore knowing your fertility status, we will show you red (for Prevent) or brown (for Plan) days before giving green days. This could mean a couple of months depending on your own body. If you start measuring while breastfeeding, you will see your first ovulation and will know when to expect your first period.
The first cycles after pregnancy may be irregular, so just keep measuring while your body is working to get back to regular.
We recommend that you measure your temperature after the longest stretch of sleep you normally get during the night, regardless of when you wake up, and that you measure instantly upon waking up - which means before tending to your baby. Try to find a routine for your measuring that works for you and your family, and measure before moving around in bed.
What you can do if the thermometer beep disturbs the family:
Turn off the thermometer after the first beep in the morning, and turn it back on whenever you are ready to start your day. The value is shown for roughly 2 seconds, so please make sure that you have the lights on and are ready to read it quickly before turning it back on. This can be re-done as many times as you wish, as long as you turn it off before it flashes onward to start measuring again.