Understanding Ovulation: Timing And Techniques For Conception

Overview

What is ovulation?

Ovulation occurs when the dominant follicle in the ovary of someone assigned female at birth ruptures, releasing an egg (ovum). This is called ovulation. The egg is released into the abdominal cavity, where it is taken up by the fimbriae, which are finger-like projections at the ends of your fallopian tubes. The fimbriae sweep the released egg into the fallopian tube, where it can potentially be fertilised by a sperm cell.¹

Why is the timing of ovulation important in conception?

Your fertile window is dependent on when ovulation occurs. Your fertile window spans the 5 days before ovulation occurs, and the day of ovulation itself. The reason for the length of the fertility window is that sperm can survive in the female reproductive tract for 5 days after ejaculation. In contrast, after ovulation, the released egg cell only survives between 12-24 hours. Therefore this is the only period where the sperm can fertilise the egg cell.

Phases of the menstrual cycle

Follicular phase

The follicular phase, also known as the proliferative phase, occurs between days 1-14 of the menstrual cycle, assuming the cycle is 28 days long. Day 1 is marked by the onset of menstrual bleeding.¹

During the follicular phase, a hormone called follicular stimulating hormone (FSH) drives the development of ovarian follicles, which are fluid-filled structures containing one egg each.¹

During this phase, communication between your brain and your ovaries results in the development of the dominant follicle (which will release the egg that has the potential to become fertilised). FSH promotes the growth and maturation of the dominant follicle, which then begins to produce the sex hormone oestrogen.¹

Oestrogen results in the development of your uterine lining, which will start to thicken during the follicular phase. As oestrogen levels rise to their highest point in your menstrual cycle, this sends a signal to your brain to produce luteinizing hormone (LH).¹

Ovulation phase

The surge of LH results in the release of the egg from the dominant follicle, a process known as ovulation, which occurs around day 14 of a typical 28-day cycle.¹

Luteal phase

After ovulation, the luteal phase begins, taking you through to the 28^th day of a normal cycle. In the luteal phase, the ruptured dominant follicle, which released the egg during ovulation, is stimulated by the hormones FSH and LH to become the corpus luteum. The corpus luteum plays a crucial role in preparing the uterine environment for a potential pregnancy, by ensuring that the uterine environment is maintained, and ready for the implantation of an embryo.

The corpus luteum produces a hormone called progesterone, which causes the lining of your uterus to mature, and become more receptive to the implantation of an embryo, assuming the released egg becomes fertilised.¹

If pregnancy does not occur, both progesterone and oestrogen levels will plummet, and the corpus luteum breaks down, forming the corpus albicans. The corpus albicans is a scar on your ovary, indicating that pregnancy has not been achieved after ovulation. The declining levels of oestrogen and progesterone result in the uterine lining breaking down, which results in menstrual bleeding.^1,2

The drop in levels of oestrogen and progesterone is crucial in your menstrual cycle, as they signal to your brain to begin producing FSH, initiating a new menstrual cycle, where FSH results in the growth and maturation of follicles in the follicular phase.¹

Signs of ovulation

Physical symptoms

The physical symptoms of ovulation are listed below:

• Cervical mucus change: During the time of ovulation your cervical mucus may become more watery, providing a more favourable environment for sperm³
• Basal body temperature (BBT) increase: BBT is your body’s lowest temperature when you are in a state of complete rest. When you ovulate your basal body temperature may increase slightly, typically less than 0.3 °C 

Common ovulation symptoms

The common ovulation symptoms are as follows:

• Mittelschmerz pain: Abdominal pain occurring on one side of your lower abdomen, typically on the side where the ovary is releasing an egg
• Cyclic mastalgia: Breast pain, where the breasts feel tender and may start to swell⁴

Optimal timing for intercourse

Best days for conception

The best days for conception are those that are during the fertile window.⁵

Frequency of intercourse during the fertile window

Having sexual intercourse every day or every other day can maximise your chances of conceiving. 

Techniques for tracking ovulation

Calendar method

The calendar method involves tracking your menstrual history to determine your fertile window. To begin, record the length of 6 to 12 of your menstrual cycles, with one cycle being from the start of one period to the start of the next.

Following this, you will need to determine when your shortest cycle is and subtract 18 from the length of this cycle, this number will tell you your first fertile day.

Then you will need to look at the length of your longest cycle and subtract 11 from the length of this cycle. The results will represent your last fertile day.

By performing these calculations, you to determine your fertile window.

Please note that the calendar method is not perfect. If you have irregular cycles, the calendar method may be unreliable for predicting your fertile days. 

Basal body temperature (BBT) charting

BBT charting can be used to predict when ovulation has occurred. There is an increase in BBT after ovulation, and this increase in BBT is maintained until menstruation. However, obtaining accurate results of BBT remains a challenge for many, as in order to obtain accurate results your BBT must be measured at the same time daily, immediately after waking. Additionally, there are many factors that can influence your BBT, resulting in inaccurate results, such as the following:⁶

• Having a fever
• Drinking alcohol
• Being stressed

Overall, BBT tracking is a useful tool to estimate when ovulation has already occurred, rather than predicting when it will occur. Therefore, this may not be the best approach for accurately predicting your fertile window. Additionally, detecting changes in BBT can be difficult, making it difficult to estimate when ovulation has occurred.^6,7

Cervical mucus monitoring (CMM)

CMM involves examining your vulvar area on non-menstrual days, and classifying your cervical mucus based on its appearance and the sensation. Type 4 cervical mucus is produced when you are in the most fertile stage of your cycle. Having sexual intercourse on days when you are producing type 4 cervical mucus has been demonstrated to increase your chances of conception at least 2-3 times higher, compared to having intercourse on days when you produce type 1 or type 2 mucus. This highlights the effectiveness of CMM in aiding conception.⁷

The classifications of cervical mucus are as follows:⁷

• Types 1 and 2: Mucus present at the start of your menstrual cycle. Type 1 has a dry sensation, whereas type 2 has a wet sensation
• Type 3: This mucus is creamy and thick, typically whitish or yellowish in colour. Type 3 has a damp sensation at the vulva
• Type 4: This mucus is transparent and elastic, resembling egg whites. This type of mucus results in a slippery sensation at the vulva

Ovulation predictor Kits (OPKs)

OPKs work by measuring the amount of luteinizing hormone (LH) in your urine. In order to accurately determine your fertile window, it is recommended that you use these kits for multiple menstrual cycles. A surge LH levels in your urine occurs prior to ovulation, allowing you to accurately estimate when ovulation will occur. OPKs have been suggested to be one of the most accurate approaches in predicting ovulation.^1,8

Fertility apps and wearable technology

Many fertility apps allow you to track your menstrual cycle and estimate your fertility window, with many adopting a similar approach to the calendar method for estimating your most fertile days.⁹

Wearable devices monitor your menstrual cycle by tracking changes in your heart rate, temperature and sleep patterns. Many studies have found that wearable devices can accurately detect physiological changes in relation to different stages of the menstrual cycle, and can aid in predicting ovulation.¹⁰

Factors affecting ovulation and fertility

Which factors affect ovulation and fertility in those assigned female at birth?

• Age: There is decline in fertility for those assigned female at birth starting in their mid-thirties, with a rapid decline after the age of 35. Diet: Eating a diet rich in vitamins, iron, folate, and antioxidants has been shown to improve fertility in those assigned female at birth¹¹
• Exercise: Many studies highlight that excessive exercise can result in anovulation (where your ovaries fail to release a mature egg during ovulation)¹²
• Stress: Excessive stress can result in anovulation^12,13
• Polycystic ovary syndrome (PCOS): PCOS is a leading cause of infertility. Those who have PCOS do not ovulate regularly, which can make it difficult to predict the fertile window¹⁴
• Thyroid conditions: Hypothyroidism can interfere with ovulation, which can affect your fertility

Summary

• Ovulation is a natural event that occurs in those assigned female at birth, where an egg is released from an ovary, making it ready for fertilisation
• When ovulation occurs, this allows the fertile window to be calculated, which is when individuals assigned female at birth are most fertile
• The fertile window spans 5 days before ovulation, and includes the day of ovulation
• You can use different techniques to track ovulation, such as the calendar method, basal body temperature charting, cervical mucus monitoring, fertility apps and ovulation predictor kits
• Tracking ovulation allows you to maximise your chances of conception