As women, we rarely pay much attention to our menstrual cycles and the complex myriad of hormones involved. However, 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.

If you’ve been trying for a baby for a while, chances are you have come across the term ‘fertile window’ before. If you have questions about your fertile window or aren’t super familiar with the phrase, don’t worry! Below, we’re outlining the four phases of the menstrual cycle and what makes up your fertile window. We’re also sharing 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.

Cycle Phase 1: Menstruation 

The first day of your cycle is when your period begins. This phase usually lasts approximately one to five days. During menstruation, the body is shedding your endometrial lining because implantation and consequent pregnancy did not occur. 

Cyle Phase 2: Follicular Phase 

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

On average, you have approximately 20 follicles per cycle. Usually, only one 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.

Cycle 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 24 hours, unless it meets sperm during this time it will die.

Cycle Phase 4: Luteal Phase

For the next two weeks, the sack in which the egg was developing (the corpus luteum) stays on the surface of the ovary. 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 fertilized 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.

Signs That Can Indicate Fertile Window

Knowing the day we ovulate is crucial for improving our conception success rates, as this tells us our fertile window. The fertile window is the day an egg is released from the ovary (ovulation), plus the five days before or after this, as sperm can survive for five days post ejaculation. That being said, you are most fertile in the three days before ovulation. 

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

  • Cervical Mucus: Your cervical mucus becomes wet, stretchy, and resembles an egg white consistency as you’re entering your fertile window. Throughout your cycle you will likely experience different textures to your cervical mucus. Straight after your period, it may be quite dry. As ovulation approaches, it will turn to a creamy consistency. In the days before ovulation, it 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.
  • Cervical Position: Like 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. If you were to touch it, it would feel like the tip of your nose. As you approach ovulation, the cervix rises up and becomes softer, moister and open. This is an indication that ovulation is fast approaching. 
  • Basal Body Temperature: 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. If you're interested in tracking, OvuSense is a fantastic tool to use for an extremely accurate and reliable reading. Understanding your cycle can transform fertility success rates and optimise chances of natural conception. 
  • 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 that it’s time to get to babydancing!

If you are new to tracking the physical signs and symptoms of your cycle, you may find it beneficial to keep a diary of your observations 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?

Having PCOS (polycystic ovarian syndrome), suboptimal thyroid, lack of periods or being underweight are just a few reasons women might not be ovulating. Speaking to your doctor (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, I 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 eating lots 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 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 fertility, such as an imbalance of good and bad bacteria in the vaginal microbiome. It could be due to your partner's low sperm count, shape and motility (which is 50% of the equation!), or it could be due to high stress levels, which means the body is preventing implantation. Fortunately, there are many natural interventions that can be used to improve fertility.


About Gail Da Silva Madalena

Gail Da Silva Madalena is a registered nutritional therapist specializing 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. Gail is the fertility and pregnancy specialist at The Natural Balance based in London.