Whether it’s craving surgery foods, feeling bloated, getting to grips with mood swings or dealing with breakouts, fluctuating hormones during our menstrual cycle are responsible for a lot.

In fact, it’s our hormones that are in charge of telling our organs what to do and when to do it. So, when it comes to essential bodily processes like our menstrual cycle and its health, they’re integral. It’s no wonder then, that an ever-increasing number of women are looking for ways to track and monitor their hormones to get a better understanding of their ovulation and fertility.

Temperature tracking is one method that claims to do just this. It’s based on the fact that our hormones and our body temperature are inextricably linked, especially when it comes to ovulation.

“Hormonal fluctuations during the menstrual cycle cause changes in the body’s core temperature,” Dr Louise Newson, GP, hormone expert and menopause specialist tells Stylist. This means tracking the body’s basal body temperature (BBT) – aka the body’s resting and lowest temperature – can be useful for menstruating women.

But, what about people who don’t menstruate? Can people who deal with conditions like Polycystic Ovary Syndrome (PCOS), endometriosis and anovulation learn more about their hormones through temperature tracking? We asked Dr Newson how useful the method is for women with irregular cycles. 

Temperature tracking is one of many methods that can be used to understand when a menstruating woman has reached the point of ovulation in their cycle, when their period might be, and when they are at their most fertile. It’s linked to the body’s hormones because it’s the hormonal fluctuations that take place during the menstrual cycle – as the body prepares for a potential pregnancy and then resets when it recognises there isn’t one – that causes body temperature to fluctuate.

Our reproductive system is influenced by hormones regulated by the hypothalamus and the pituitary gland. These hormones are the follicle-stimulating hormone (FSH) and the luteinizing hormone (LH). Both of these hormones travel to the ovaries where they influence estrogen and progesterone levels and help the follicles inside the ovaries mature.

During the first phase of the menstrual cycle – the follicular phase – the body experiences increased levels of estrogen and low levels of progesterone. During the second phase – ovulation – estrogen levels peak. While, in the third phase – the luteal phase – the body secretes more progesterone to prepare the uterine lining for implantation of a fertilised egg.

It’s these increased levels of progesterone during this phase of the menstrual cycle that cause the body’s normal core temperature, which ranges between 36.1°C and 37.2°C, to increase by  0.2°C to 0.5°C after ovulation. 

“Temperature tracking can help identify the phases of the menstrual cycle by showing the phasic pattern of temperature changes,” says Dr Newson. “The first phase – the follicular phase – is marked by lower temperatures. Following ovulation, a rise in temperature indicates the luteal phase. This temperature shift can help pinpoint ovulation and confirm that it has occurred.”

Basal body temperature is different from the body’s regular temperature, so it’s important to measure it in a certain way to make temperature tracking work.

Temperature tracking involves taking your BBT every morning at the same time, ideally before getting out of bed or engaging in any physical activity. It should be done with a basal thermometer, which is more sensitive than a regular thermometer and more accurate as it measures temperature to two decimal places.

“Consistency is key, so measuring at the same time each day and under the same conditions is crucial for accuracy, ” says Dr Newson. “You also need to ensure you use the same method each time, whether you’re taking your temperature orally, vaginally, or rectally.”

It’s also important to record your temperature consistently and be aware of any factors that might affect readings, such as illness. It’s also important not to measure your temperature after physical activity. 

If done correctly, temperature tracking is generally reliable but it can be influenced by various external factors. “It provides a good indication of ovulation but is certainly not foolproof due to potential hormone disturbances, irregular cycles and human error in measurement,” says Dr Newson.

Consistency in measurement and recording helps improve accuracy, however relying solely on BBT for birth control might lead to unintended pregnancy as it is less effective than most other birth control methods.  

At the moment, temperature tracking is predominantly used for monitoring reproductive health, so for women with PCOS, endometriosis or anovulatory cycles, temperature tracking is more challenging due to irregular ovulation or lack of ovulation. “The temperature patterns may not be as clear,’ says Dr Newson. “So, additional methods or medical consultation are necessary to accurately monitor the menstrual cycle.”

However, temperature tracking can be useful to identify menstrual irregularities. For example, if you don’t notice a temperature change while tracking your basal temperature it may indicate hormonal imbalances or other health problems that require a visit to the doctor.

When it comes to scientific studies, there’s been little research into what temperature tracking can reveal for women who don’t menstruate. However, one study from The Hershey Medical Center of the Pennsylvania State University investigating the association between “pelvic endometriosis and altered basal body temperature” found a “significant association” between “the presence of pelvic endometriosis (without previous treatment) and the appearance of a late decline in BBT during the early follicular phase of the menstrual cycle.” It suggests that “the early clinical diagnosis of endometriosis in infertile women” could be helped by tracking the basal body temperature.

Another, more recent, study from the German Society of Gynecology and Obstetrics looking into whether continuous body temperature monitoring can improve the diagnosis of female infertility concluded that it could “improve the standard diagnostic procedures used to determine ovulatory dysfunction, especially if dysfunction is due to luteal phase deficiency and polycystic ovary syndrome.”

Images: Getty