TTC charting – what your temperature can reveal about your sex hormones

Here at The Ribbon Box, we know firsthand how overwhelming cycle tracking (read, TTC charting) can be when you’re trying to conceive. The uncertainty of pinpointing your exact ovulation peak (tick off these ovulation boosts, if you haven’t already) , the pressure to chart everything perfectly—it’s easy to spiral into obsession. I (TRB founder Eloise) remember stressing over whether I had a short luteal phase, despite having no real evidence. Months later, I realized I didn’t.

That’s why we’re sharing expert guidance to help you track your cycle accurately and with less stress. Keep reading for practical charting tips to make the process easier and more intuitive.

Basal body temperature (BBT)

Your basal body temperature (BBT) is the lowest temperature your body hits while at rest, usually about two hours before you wake up. It’s the best way to measure how your sex hormones (estrogen and progesterone) impact your body.

Once you’re up and moving, your thyroid kicks in and takes over temperature regulation—so measuring BBT after waking won’t give you an accurate read on your hormones. That’s why BBT can only be measured while you’re still asleep.

Thermogenic effect

This refers to how hormones influence your body temperature. Some hormones raise it, others lower it. But how do you actually track your temperature while you’re sleeping? Don’t worry, we’ll get to that soon!

Hormones & your menstrual cycle – what your temperature can tell you

The “normal” cycle

The ‘textbook cycle’ – bear in mind, textbook may not apply to you! –  is 28 days long, with ovulation happening on day 14.

• Healthy cycles can range from 26–35 days, with ovulation happening between days 12–18.
• If your cycle falls outside this range, it might be worth keeping an eye on what happens cycle to cycle, and even checking in with your doctor.
• Another important factor? Consistency. Take your longest and shortest cycle from the past 3–6 months and subtract them. If there’s more than a 5-day difference, that could indicate irregularity.

A normal cycle has four phases: menstruation, follicular (pre-ovulation), ovulation, and luteal (post-ovulation). Your period (menstruation) marks day 1 of your cycle, and the last day of your luteal phase is the last day before your next period starts.

Quick tip: Tracking your cycle length, symptoms, and temperature changes can help you spot irregularities early on.

Estrogen & FSH – the follicular phase

This phase happens in the first half of your cycle, before ovulation.

• Estrogen, released by your ovaries, helps mature your follicles (aka, helps eggs grow) and thickens your uterine lining.
• FSH (follicle-stimulating hormone) teams up with estrogen to support egg development.
• Once estrogen peaks, it triggers a surge in luteinizing hormone (LH), which kickstarts ovulation.
• Neither estrogen nor FSH have a strong impact on body temperature, so BBT remains low during this phase.

LH – the ovulation phase

Luteinizing hormone (LH) spikes, to trigger ovulation.

• This is the hormone that at-home ovulation predictor kits measure.
• LH itself doesn’t raise body temperature.

Heads up: An LH surge doesn’t always guarantee ovulation. In some conditions, like PCOS, LH levels can stay elevated, leading to false positives on ovulation tests.

Progesterone – the luteal phase

After ovulation, the luteal phase kicks in, lasting around 14 days.

• Progesterone, released by the ovaries, takes center stage.
• This hormone helps maintain the uterine lining and prevents your period from starting if pregnancy occurs.
• If pregnancy doesn’t happen, progesterone levels drop, and your period begins. If pregnancy does occur, progesterone levels keep rising.
• Progesterone has a strong thermogenic effect, meaning it noticeably raises your BBT.

The menstrual phase

When progesterone drops sharply, your period starts.

• At this point, all hormones are at their lowest, so tracking temperature isn’t as important.
• A healthy period typically lasts about 5 days and should be pain-free.
• A good flow means changing a regular pad/tampon every 4 hours. If you’re changing more often, it could indicate heavy bleeding (menorrhagia).
• Light brown spotting at the end of your period is normal. But spotting more than 1–2 days before your period could signal a hormonal imbalance.
• Bright red bleeding marks day 1 of your cycle.

How does temperature charting work?

Fertility temperature charting, also known as basal body temperature (BBT) tracking, is a method used to monitor ovulation by recording daily temperature changes. The basal body temperature is the body’s lowest resting temperature, typically measured first thing in the morning before any movement.

Throughout the menstrual cycle, hormonal fluctuations cause slight shifts in BBT, with temperatures typically lower during the follicular phase (before ovulation) and rising after ovulation due to increased progesterone levels. By tracking these changes over multiple cycles, we can identify patterns that indicate when ovulation has occurred.

To effectively chart BBT, you need a reliable digital thermometer that measures to at least one decimal place (e.g., 97.61°F). The temperature should be taken at the same time every morning before getting out of bed, after at least three to four hours of uninterrupted sleep.

Next up, you’ll need to record your temperature readings on a chart or in a fertility tracking app. A sustained temperature rise of about 0.4 to 1°F (0.2 to 0.5°C) that lasts for several days indicates ovulation has passed. BBT doesn’t predict ovulation in advance – it confirms that it has already happened.

When used consistently, fertility temperature charting can be a helpful tool for those trying to conceive or practicing natural family planning. It works best when combined with other fertility awareness methods, such as monitoring cervical mucus and using ovulation predictor kits, to improve accuracy in identifying the fertile window.

While BBT tracking provides valuable insight into cycle regularity and hormonal health, factors like illness, stress, and disrupted sleep can affect temperature readings. If you have an irregular cycle or underlying health condition, we’d recommend consulting a healthcare professional for additional guidance in understanding your fertility patterns.

Can BBT tracking tell me more about my hormones? Absolutely.

Your sex hormones directly influence your basal body temperature (BBT), meaning tracking it can give you valuable insight into your cycle. If your BBT trends don’t align with what’s typically expected, it could be a sign that your hormones aren’t functioning as they should.

Here’s your ultimate BBT cheat sheet—these are the key temperature ranges to look out for:

• Follicular phase (before ovulation): 97.2 – 97.5°F (36.2 – 36.4°C)
• Ovulatory phase: A temperature rise of at least 0.4°F (0.2°C) the day after ovulation.
• Luteal phase (after ovulation): Above 98.0°F (36.7°C) 

Now, let’s break this down with some real examples.

IRL examples

Progesterone deficiency

After ovulation, your temperature rises from 96.8°F (36.0°C) to 97.34°F (36.3°C) – which is a good increase. But here’s the issue: your luteal phase temperatures never reach the ideal 98.6°F (37.0°C), peaking at just 97.7°F (36.5°C) for one day. Plus, they fluctuate a lot. This suggests a progesterone deficiency, which could lead to symptoms like premenstrual spotting and infertility.

Estrogen excess

Ideally, the follicular phase should last no more than 14 days, but yours drags on for 21 days. One possible reason? Too much estrogen.

Your temperature readings back this up – they climb to 97.9°F (36.6°C) when they shouldn’t go above 97.5°F (36.38°C). This suggests delayed ovulation due to estrogen excess, which can lead to symptoms like breast tenderness and menstrual cramps.

Estrogen deficiency

Now, let’s look at what happens when there isn’t enough estrogen. Your follicular phase temperatures are all over the place – lots of peaks and valleys – meaning your hormones are struggling to regulate. On many days, your temperature dips below 97.16°F (36.2°C), which signals estrogen deficiency.

As a result, your ovulation is delayed to day 17. You may experience hot flashes and night sweats due to this imbalance.

Natural ways to track ovulation (beyond BBT)

While tracking your basal body temperature (BBT) is a great way to confirm ovulation, you can also use other natural signs your body gives you. Here’s how to read them effectively.

Cervical mucus: your body’s natural fertility clue

Your cervix produces fluid throughout your cycle, and its consistency can indicate where you are in your fertility window.

• Creamy or lotion-like mucus is common in the follicular phase before ovulation as estrogen levels rise. It is white and has a texture similar to lotion or sunscreen.
• Clear and stretchy mucus is a sign of peak fertility. Ovulatory fluid is slippery and resembles raw egg whites. If this lines up with a temperature spike on your BBT chart, ovulation is very likely.
• Tacky or dry mucus appears after ovulation when the cervix closes. It may be thick and sticky or disappear altogether, signaling that ovulation has passed.

Your cervical mucus will generally be clear, white, or creamy. If it looks or smells unusual, it may indicate an infection.

Cervical position: the inside scoop

Checking your cervix’s position can provide another ovulation clue. This method takes practice but can be a useful addition to tracking.

• How to find it: Insert a clean finger toward the back of your vagina until you feel a firm structure similar to the tip of your nose. That is your cervix.
• Why it matters: Your cervix moves throughout your cycle. When you are not ovulating, it sits lower and feels firmer. Around ovulation, it moves higher, softens, and opens slightly to help sperm travel through.
• What to do: Check at the same time each day to notice subtle changes. With practice, you will become familiar with how it shifts throughout your cycle. Remember, clean fingers only!

Other ovulation signs you might notice

• Increased libido
• One-sided cramping, also known as Mittelschmerz
• Breakouts, breast tenderness, or bloating

Not everyone experiences these symptoms, and that is completely normal.

What your symptoms might indicate, hormonally

Lab tests are great, but sometimes your body is already giving you the clues you need. Your symptoms (and even your temperature) can reveal a lot about what’s going on hormonally.

Here’s a quick breakdown of common hormonal imbalances and the symptoms they’re often linked to:

Low estrogen

• Hot flashes
• Vaginal dryness
• Headaches
• Light periods
• Dry skin
• Hair loss
• Acne
• Low libido
• Brain fog/memory issues
• Insomnia
• Weight gain

High estrogen/FSH

• Breast tenderness
• Low appetite
• Fibrocystic breasts
• Painful or heavy periods
• Mood swings and anxiety
• Water retention and bloating
• PMS

High progesterone

• Acne
• Bloating and water retention
• Fatigue
• Weight gain
• Anxiety
• PMS

Low progesterone

• Anxiety
• Low libido
• Mood swings and headaches
• PMS
• Irregular periods
• Premenstrual spotting
• Increased miscarriage risk

Your symptoms can also give you insight into where you are in your cycle and whether you’ve ovulated. Tracking patterns over time can help you better understand your body and any hormonal shifts that may be happening.

While these symptoms are common, they aren’t necessarily ‘normal’ – and you don’t have to put up with them. If something feels off, check in with a healthcare provider who can help you get to the root of it.

I’m not ovulating on cycle day 14 – what does that mean?

If you’ve been tracking your cycle and noticed that you’re not ovulating on day 14 (or at all), you might be wondering what’s going on. While the ‘textbook’ menstrual cycle lasts 28 days with ovulation on/around day 14, real-life cycles vary.

If your basal body temperature chart isn’t showing clear signs of ovulation, there could be an underlying reason. Let’s break it down.

Long cycles

A cycle longer than 35 days is considered a long cycle, often due to ovulation issues (for example, PCOS) – or no ovulation at all (anovulation).

Ovulation is necessary for pregnancy, and a delay suggests that your ovaries might not be responding efficiently to hormonal signals. This can mean your egg takes too long to mature, reducing its quality. Hormonal shifts in your 30s can also lengthen your cycle.

Short Cycles

If your cycle is shorter than 25 days, you may be ovulating prematurely. Early ovulation can result in the release of an egg that isn’t fully mature, making conception difficult.

Cycles often shorten in your 40s due to declining ovarian reserve, meaning fewer eggs remain.

Anovulation (no ovulation)

If your BBT chart remains relatively stable without a clear temperature spike, you may be experiencing anovulation – when ovulation doesn’t occur. This often results in irregular or heavy bleeding due to an estrogen build-up without the balancing effect of progesterone.

If you’re experiencing unpredictable cycles, it’s worth discussing with a healthcare provider.

Possible causes of irregular or absent ovulation

PCOS (Polycystic Ovary Syndrome)

PCOS is a common condition linked to insulin resistance and higher-than-normal testosterone levels, both of which can prevent ovulation. Symptoms may include acne, excessive hair growth (especially on the face or chest), and weight fluctuations.

Thyroid imbalances

Both hypothyroidism (low thyroid hormone) and hyperthyroidism (high thyroid hormone) can disrupt ovulation and lead to irregular cycles. If you’re experiencing fatigue, weight changes, or hair thinning, thyroid testing might be worth exploring.

Hypothalamic amenorrhea

This occurs when the brain doesn’t send enough hormonal signals to trigger ovulation, often due to stress, low body weight, or intense exercise. If you’ve lost your period due to heavy training or dietary restrictions, addressing these lifestyle factors may help restore ovulation.

Fibroids & ovarian cysts

Fibroids (benign uterine growths) and ovarian cysts (fluid-filled sacs on the ovaries) can both be linked to high estrogen levels. These can interfere with ovulation, cause heavy or prolonged bleeding, and even impact embryo implantation.

When to see a doctor

If you consistently have irregular cycles, aren’t seeing signs of ovulation, or have symptoms like excessive bleeding, acne, or unexplained weight changes, it’s a good idea to check in with a healthcare provider. They can help identify underlying issues and suggest treatments to support hormonal balance and cycle health.

Your cycle isn’t necessarily supposed to look like the textbook version – every body is different. But understanding what’s normal for you is key to supporting your reproductive health.

Want to learn more about cycle tracking and optimizing your hormones? Stay informed (our weekly newsletter round-up will keep you on track), listen to your body, and don’t hesitate to seek support if something feels off.