If you follow natural cycles for contraception, or you’re trying to conceive, you’ll need to be really good at knowing when you’re ovulating. It can be tricky though, so it’s important to track your periods and symptoms so you can start to understand you body.
When does ovulation happen?
An average menstrual cycle is said to run over 28 days.
Ovulation (the release of an egg ready to make a baby) tends to happen at the midpoint of a cycle, with day 1 being the start of the period (the LMP date) and ovulation being around day 14 (roughly 2 weeks after the start of the last period).
Some people have shorter cycles, and some longer cycles, and this makes the “fertile window” highly variable.
The fertile window tradionally is said to be between days 10 and 17 of a cycle, 3 days either side of day 14. However, in one study, more than 70% of women are in a fertile window before day 10 or after day 17. In fact, there are very few days that pregnancy couldn’t theoretically be possible. This is good news for those trying to conceive, but not so good if you’re using natural cycles to avoid getting pregnant.
Knowing as many signs of ovulation as possible will also help you to know what is going on for your body specifically.
Signs of ovulation
It’s around the mid-point of your cycle
If you keep track of your periods, and you’re around day 14 of your cycle, then you may well be gearing up to ovulate, or have already ovulated. But as already mentioned, ovulation doesn’t always occur at the mid-point. There is also a myth that ovulation always happens 2 weeks before a period is due, this is not the case and actually only occurs in 10% of women like this.
Couple this tracking with the other signs listed to give yourself a better chance of predicting ovulation.
Your libido changes
Many women report that during the fertile phase of their cycle, they feel more like having sex. In fact, there is research to suggest that we dress differently and are more likely to spend money during this phase too.
We often think that testosterone is to blame for this shift, and women who are perimenopausal or menopausal do feel like their libido is better wiith testosterone replacement, however it is likely that it is the surge in oestrogen that occurs when ovulation happens that sexual desire changes.
Cervix and mucus changes
One of the signs of ovulation is a chance to your cervical mucus. It goes from being sticky and thick, to being thin, watery and stretchy. This is thought to be beneficial to the successful passage of sperm through the cervix.
If you were to reach inside your vagina with 2 fingers and feel the cervix, it would feel a little softer than usual. It’s usually quite firm (like the tip of your nose), but when oestrogen is high, the cervix softens. A speculum examination might also show signs of a cervical ectropion. This is a red coloured, glandular-type tissue that extends onto the surface of the cervix caused by the oestrogen surge. It usually retracts away during less fertile times. It’s quite fragile, so sometimes you might notice vaginal spotting after sex around this time due to the penis hitting the surface of the ectropion.
If this happens a lot though, don’t assume it is related to an ectropion without confirmation from a healthcare professional. Always make sure your smear tests are up to date because erratic spotting can be a sign of cancer of the cervix too.
As well as tracking your periods, start to keep an eye on your temperature. This is known as the basal body temperature and should be recorded at the same time every day as soon as you wake up using the correct type of thermometer that can detect subtle changes. Eventually you should start to notice a pattern. Basal body temperature may increase slightly by around 0.2-0.6 C when you ovulate, but it needs to be sustained for three days or more to be convinced it is due to ovulation and not something else. If the temperature does not return to baseline, it’s a possible very early indication that pregnancy has happened.
It happens because the progesterone released by the corpus luteum (the husk left behind in the ovary after the egg has left) acts on the hypothalamus that affects your body temperature. Pregnancy sustains the corpus luteum wheras not being pregnant doesn’t and the temperature eventually drops back to baseline again.
Be warned though, drinking alcohol and being sick or stressed can affect the accuracy of the results.
Lower abdominal cramping
Some women notice a mild cramping in their lower abdomen during ovulation. This is another sign of ovulation known as Mittelschmertz. Women who experience this may not experience it every month, and it can sometimes be mistaken for illnesses like appendicitis. Mittelschmerz can be felt on either side of the lower abdomen, but it will generally be on the same side as the developing follicle leading up to ovulation. The pain usually stops within three to twelve hours of ovulation happening, but some people can notice it persisting until a period happens (especially if they have undergone surgery on an ovary). It can also be felt in the lower back. If this happens regularly for you, it can be a fairly good indicator of ovulation.
If the pain however is really severe and you think you might be pregnant, always get checked by a healthcare professional and do a pregnancy test just in case.
High Oestrogen Effects
Ovulation co-incides with the “oestrogen surge” – a flood of oestrogen in your blood stream. This is turn stimulates lutenising hormone (LH) to rise rapidly and this triggers ovulation. Ovulation tends to occur around 28-36 hours after the start of the LH surge, or 8-20 hours after it hits it’s peak. The rise in oestrogen contributes to symptoms like nausea, headaches and breast tenderness. You might also notice that your senses are heightened too. After ovulation there is a rise in progesterone, and this contributes to the achey boob feeling too, as well as PMS-symptoms such as moodiness, tearfulness, acne, bloating and tiredness.
Blood tests to detect signs of ovulation
Blood tests can be helpful to detect ovulation, but their use is limited. A raised progesterone level at around 7 days after you think you’ve ovulated is a good sign of ovulation, but achieving an accurate reading is hard due to the nature of how unpredictable ovulation is.
If you were able to track your LH levels across your cycle, you would see the rise and fall with ovulation. Oestrogen would also rise and fall as the cycle progressed.
The problem is, beyond a laboratory setting, most people are not going to be sending blood tests off every day to try and work this out.
We tend to stick with a post-ovulation progesterone, and check that the FSH and LH are both low during days 1-3 of a cycle (the first 3 days of the period). If they are raised, it can be a sign of something else going on like premature ovarian insufficiency, perimenopause and polycystic ovary syndrome.
Are ovulation testing kits worth using?
Many women trying to conceive or avoid pregnancy buy ovulation testing strips to try and work out when they are ovulating. I was no different! They can be useful, but they might be misleading. One version works on the principle of detecting LH in the urine. There should be a marked change in the intensity of the “positive” line on the strip when ovulation has occurred. This tends to occur around 24 hours before ovulation. So coupled with the other signs as above, you can be more convinced that a positive urine strip corresponds with ovulation. Depending on the sophistication of the kit can also check for high levels of estrone-3-glucuronide (E3G) which is also raised during ovulation.
Another type of kit is a saliva test kit looking for fertility ferning. Right before ovulation, a person’s saliva changes. If you look at a sample of this dried saliva under a microscope, it is said to resemble fern leaves. This pattern results from an increase in the level of salt and oestrogen during ovulation.
The trouble is though, these methods are not reliable in the presence of conditions such as POI, perimenopause, luteinised unruptured follicle syndrome or PCOS to name but a few.
No one sign of ovulation is accurate enough, but combined it should give you the best chance of knowing what is going on inside your body. Get into the habit of tracking your cycles and symptoms and hopefully you’ll see a pattern emerge. If you’re trying to conceive, don’t always aim to have sex around ovulation, because as you’ve read, this can happen at any time in a cycle, so have sex every 2-3 days to maximise your chances. If you’re trying to avoid pregnancy, beware of the pitfalls that come with natural cycles and be more cautious, aving a lower theshold for using condoms if you’re not sure.
In any case, good luck!
Dr Nikki x
- Allen J Wilcox, branch chief, David Dunson, investigator, and Donna Day Baird, senior investigator (2000); The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC27529/
- Maurand Cappelletti and Kim Wallen (2016); Increasing women’s sexual desire: The comparative effectiveness of estrogens and androgens: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720522/
- Women’s spending behaviour is menstrual-cycle sensitive: https://www.sciencedirect.com/science/article/abs/pii/S0191886910004289
- Analysis of pre-ovulatory changes in cervical mucus hydration and sperm penetrability: https://pubmed.ncbi.nlm.nih.gov/9288332/
Kaitlyn Steward; Avais Raja (2023); Physiology, Ovulation And Basal Body Temperature: https://www.ncbi.nlm.nih.gov/books/NBK546686/
Nathan R. Brott, Jacqueline K. Le (2023); Mittelschmerz: https://www.ncbi.nlm.nih.gov/books/NBK549822/
- J Kerin (1982); Ovulation detection in the human: https://pubmed.ncbi.nlm.nih.gov/6821195/