Did you know a thermometer can tell you when you’ve ovulated? Yup. In a healthy cycle, the release of progesterone following ovulation increases your body temperature and so if you track your temps, you can figure out when you’ve ovulated!
WHAT IS IT?
According to Queen Toni Weschler, by definition, the thermal shift is “a rise in your waking temperature that divides the preovulatory low temps from the later, postovulatory high temps on a biphasic chart (or app). It usually results in temperatures that are at least 2/10ths of a degree higher than the previous 6 days.” (Weschler, Toni. 2006)
So basically, it’s a temp shift of at least 2/10ths of a degree, from your temperatures over the last 6 days.
WHY IS THIS IMPORTANT INFO?
When a thermal shift occurs in a healthy cycle, it is the indication that you have ovulated. This can help you predict when to have sex if you wanna get pregnant. Or avoid sex if you don’t. Because the truth is, most of us do not ovulate on that “Day 14” that everyone schedules themselves around. You may not actually ovulate until day 18, or you may ovulate on day 12, which if you are planning on day 14, can really screw you up! Noting your thermal shift can also alert you to potential hormonal imbalances or an unhealthy cycle if you realize that you don’t have a thermal shift occurring.
HOW DO I FIND MY THERMAL SHIFT?
To find your thermal shift, you need to take your temperature first thing in the morning.
And we mean, first thing. Hold that pee. Get somebody else to start your morning brew. Temp taking takes precedent.
Using a period tracker can be very helpful in keeping track of your temps over time and being able to look back and see when your shift occurred.
CAN I USE ANY OLD THERMOMETER?
BBT or Basal Body Thermometers are your best bet because they give your more specific temperature reads…remember, we are talking 2/10th of a degree here!
WORD TO THE WISE:
Using fertility apps that only use temperature to predict when you’re fertile isn’t as effective as using the fertility awareness method, which combines temperature with cervical fluid and cervical position. Technically speaking, taking your temperature can only ever tell you that you’ve already ovulated; it can’t predict when it’s going to happen next (Knight, J. 2017) or when you are most fertile.
If you are on hormonal contraceptives you will not have a true thermal shift so it will be difficult to learn about your overall health via tracking.
Contributions and Research by: Natasha Richardson, Herbalist and owner of Forage Botanicals, London UK