Knowing Your Fertile Window

Updated: Apr 14

If you’ve been trying for a baby for a while, chances are you have come across the term ‘fertile window’ before. As women, we rarely pay much attention to our menstrual cycles and the complex myriad of hormones involved. This all changes when we decide we want to conceive, at which point it feels like you need a crash course in the female reproductive system to figure out when it’s the right time to get active between the sheets.


Below outlines the 4 phases of the menstrual cycle, and the crucial steps we need to go through to ensure healthy growth of eggs, ovulation and maintaining the right environment for an egg to implant.

fertile window

Phase 1. Menstruation

Day 1 of your cycle is when your period begins. This usually lasts approx. 1-5 days. In this phase the body is shedding your endometrial lining because implantation & consequent pregnancy did not occur.


Phase 2. Follicular phase

The follicular phase starts on the first day of your period and ends with ovulation. It’s where your hypothalamus/pituitary gland signals the releases of FSH (follicle stimulating hormone), which promotes the growth and maturation of immature eggs in your ovaries.


On average you have approximately 20 follicles per cycle. Usually only 1 of these follicles will mature into an egg and go on to ovulate. The growth of these follicles prompts the lining of the endometrium to thicken in preparation for pregnancy. Oestrogen is dominant during this time and is what elevates FSH levels.


Phase 3. Ovulation

Ovulation usually happens around day 14 of your cycle, although this is extremely variable person to person (this is why Ovusense is so invaluable at tracking the exact day a woman ovulates!).

As oestrogen peaks the hypothalamus releases another hormone called GnRH (gonadotrophin-releasing hormone), which prompts the pituitary gland to produce a surge of luteinising hormone (LH). This increase in LH enables the egg to burst through the wall of the ovary – or ovulate. It is then carried down the fallopian tube into the uterus. The lifespan of an egg is 24hrs, unless it meets sperm during this time it will die.


Phase 4. Luteal phase

The sack in which the egg was developing in (the corpus luteum) stays on the surface of the ovary for the next 2 weeks. It releases high quantities of progesterone and small levels of oestrogen, which maintain a thick endometrial lining that is vital for implantation and a healthy pregnancy. If a fertilised egg implants then the corpus luteum will continue to pump out progesterone. If pregnancy does not occur then it withers and dies, dropping the levels of progesterone significantly. This causes the endometrial lining to break down and results in a period.


Knowing the day we ovulate is crucial for improving our conception success rates. The ‘fertile window’ is the day an egg is released from the ovary (ovulation) and 5 days either side of this, as sperm can survive for 5 days post ejaculation. You are most fertile in the 3 days before ovulation.

Signs that can indicate you’re fertile


There are several ways your body can tell you you’re entering your fertile window. If you’re trying for a baby, look out for the below:


female fertility signs

1. Cervical Mucus

Your cervical mucus becomes wet, stretchy and an egg white consistency. Throughout your cycle you will likely experience different textures to your cervical mucus. Straight after your period you will most likely be quite dry. As ovulation approaches this will turn to a creamy consistency. In the days before ovulation this will become wetter, until you get the egg white texture, which signifies your most fertile time. This is the optimum time to have intercourse for conception.


2. Cervical Position

As well as cervical mucus, your cervical position will also change throughout your cycle. While you are not fertile, the cervix is normally low and hard and the opening to the uterus is closed. It feels like the tip of your nose if you were to touch it. As you approach ovulation, the cervix rises up and becomes softer, moister and open. This is an indication ovulation is fast approaching.


3. Ovulation Kits

With busy lives it can sometimes be hard to tune in to our bodies and notice the subtle changes happening around ovulation. This is where ovulation predictor kits can be extremely helpful. Traditionally, many women have relied on urine test kits to look out for rising levels in luteinising hormone just before ovulation. They try to indicate whether you are in your peak fertility window. Unfortunately, these at home kits are not always 100% accurate and can give you false results. This is where the Ovusense is so valuable to give 99% accuracy in your ovulation window.


4. Basal Body Temperature

Another method of tracking your cycles and capturing your fertile window is through basal body temperature tracking. Monitoring our resting temperature throughout our cycle can identify each phase of the menstrual cycle and alert us when we have ovulated. Our temperature dips and then has a high spike around ovulation, staying high throughout the luteal phase and then dropping again if pregnancy doesn’t occur. There are many ways to track your BBT, however Ovusense is a fantastic tool I frequently recommend to clients for an extremely accurate and reliable reading. Understanding your cycle can transform fertility success rates and optimise chances of natural conception.


Bonus sign - Increase in Libido

You may find that you’re more ‘up for it’ in the days leading up to ovulation. The hormone oestrogen which rises before ovulation can give you that excited feeling in the bedroom which is nature's way of telling you its time to get going between the sheets!


If you are new to tracking the physical signs and symptoms of your cycle then you may find it beneficial to keep a diary of what you notice throughout the month. Once you become more in tune with your menstrual cycle it will become second nature and you will naturally notice the physical and emotionally connected changes throughout the month


What If I don't think I am ovulating?

There can be several reasons that a woman might not ovulate such as having PCOS (polycystic ovarian syndrome), suboptimal thyroid, lack of periods or being underweight. Speaking to your GP (or if you want to take a more natural approach; a nutritional therapist) is an important starting point to ensure you are ovulating.


A day 21 progesterone blood test is often taken to assess if ovulation occurred, but depending on the length of your cycle this may not always show up with an accurate result.


Luckily there are many things which can be done to improve ovulation. As a nutritionist we see this problem a lot in our fertility clinic and we tend to use a variety of natural methods to support this. Eating a health balanced diet is absolutely essential when trying to promote ovulation and this includes a diet of whole grains, fresh fruits and vegetables as well as oily fish such as salmon and mackerel.


Some of the above reasons may need further investigation which could include hormone testing, ultrasound or a referral to your gynaecologist. In our nutrition clinic, we have a huge toolkit up our sleeve of ways to improve ovulation naturally through diet, supplementation, lifestyle changes and stress reduction.


I think I am ovulating but I am still not getting pregnant?

There could be other factors impacting your infertility. This could be due to an imbalance of good and bad bacteria in the vaginal microbiome (see our other blog on How vaginal microbiome can impact fertility). It could be due to your partner's low sperm count, shape and motility (which is 50% of the equation!), or it could be down to high stress levels which means the body is preventing implantation.


Fortunately there are many natural interventions which can be used to improve fertility so please do get in touch if you are having trouble conceiving.


Do you want support in your fertility and pregnancy journey? Book a free consultation with Gail to find out more.



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Gail Madalena

Registered Nutritional Therapist

Dip CNM, mBANT, mANP, mCNHC




Gail Madalena is a registered nutritional therapist specialising in fertility, pregnancy and women’s health. Her expertise lies in hormonal imbalances, such as irregular cycles, debilitating PMS, PCOS, endometriosis, thyroid issues and sub-optimal fertility. Her goal is to reduce hormonal side effects and symptoms by addressing the root cause of the issue. Gail helps couples optimise your nutrition and lifestyle choices, supporting you on your journey to achieving a healthy pregnancy.


I am not attempting to prevent, treat or cure any physical, mental or emotional issues. Do not disregard medical advice or delay seeking medical advice because of information you have read on this website. Do not start or stop taking any medications without speaking to your primary health care provider.
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