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Ovulation Myths Debunked

16 November 2020

When we recall what we were told about conception as we grew up and what we learned in sex education classes, we easily notice that there was a lot of information that was left out or not explained properly – and we were left believing that pregnancy should happen easily and quickly for everyone.

So many women find themselves trying to avoid a pregnancy at all costs in their 20s, just to realise in their 30s that in fact, things are a bit more complicated. In this article, we debunk common ovulation myths.

Myth 1: Menstrual cycle lasts 28 days

The length of the menstrual cycle lasts from the first day of a woman’s period to the day before her next period. We often hear about the menstrual cycle lasting 28 days however this is a myth. In fact, only 13% of women have 28-day cycles. Normal cycles can range between 21 to 35 days.

Between 14-25% of women have irregular cycles. This happens when a cycle varies more than just a few days from cycle to cycle. Cycles are also considered irregular when periods are less than 21 days apart or more than 35 days apart. It is normal to have irregular cycles in the first few years of menstruation, and close to menopause. If your periods are irregular outside these times, it’s a good idea to speak with your GP to investigate underlying causes. 

Myth 2: Ovulation happens on day 14

The ovarian cycle has 3 stages: follicular phase, ovulation and luteal phase. During the follicular phase, there menstruation and the growth of follicles that contain the eggs. Several eggs start maturing, but only one will be ovulated. After ovulation, the ruptured follicle becomes corpus luteum and starts producing progesterone, which prepares the uterus for possible implantation.

Just like not all women have cycles that last 14 days, ovulation doesn’t happen on day 14 for everyone. Ovulation happens when the maturing eggs have reached a certain developmental state and are producing oestrogen. The levels of oestrogen trigger the pituitary gland in the brain to produce LH which helps the egg to complete maturation and be released from the follicle, ready to be fertilised. A large study recently found that the majority of women ovulate on day 17.

Usually, only one egg is ovulated in each cycle, and ovaries alternate from cycle to cycle. In rare cases, women can ovulate two eggs in the same cycle, which when fertilised and implanted lead to dizygotic twins – two separate eggs are fertilised by two separate sperm.

There can also be a cycle where an egg is not ovulated – this is called anovulatory cycles. Different causes can lead to anovulatory cycles. 

Myth 3: The calendar can predict ovulation day

There are several calendars promising to predict your ovulation day. However, research shows that ovulation day varies considerably for any given cycle length and it is not possible for calendar and app methods that use cycle-length information alone to accurately predict the day of ovulation.1,2

This is mainly because the follicular phase, that leads up to ovulation, is variable from woman to woman and even in the same woman, from cycle to cycle. 

Myth 4: Basal body temperature informs when ovulation is going to happen

There are prospective and retrospective methods to identify ovulation:

  • prospective methods rely on events that happen before ovulation and indicate the presence or absence of a follicle developing, oestrogen dominance and / or LH surge;
  • retrospective methods rely on events that happen after ovulation and indicate the presence of a corpus luteum with progesterone dominance.

Basal body temperature is a retrospective method. Temperature fluctuates due to hormonal variations in the menstrual cycle. During the follicular phase of the menstrual cycle, temperature is lower, until approximately 1 day before ovulation, when it reaches its lowest point (called nadir). After ovulation, the corpus luteum begins to secret progesterone. The temperature increases and plateaus throughout the luteal phase. In late luteal phase, when the corpus luteum regresses and serum progesterone level decreases, the temperature returns to the lower range within 1 or 2 days before, or just at, the onset of menstrual bleeding.

Because one cannot identify the lowest temperature point until the subsequent rise is seen, it means we can only see if ovulation has occurred, after it has occurred. There is no more chance of pregnancy in this cycle. For this reason, tracking basal body temperature is a retrospective method.

If you are trying to conceive, a method that identifies ovulation before it happens is more useful as the Fertile Window is the day of ovulation and up to 5 days before ovulation.

Basal body temperature also presents other challenges:

  • It requires a high degree of compliance, as you need to measure temperature every morning around the same time and before you do any activity.
  • You need to interpret the chart to learn that ovulation has happened. A significant increase is at least 0,2°C that lasts for 3 days or more is a sign that ovulation has happened.
  • Account for several factors that can affect the temperature readings, like consumption of alcohol, oversleeping, difference in time zones, shift work, stress, change in room temperature, change of climate, illness, and medications.

Myth 5: Ovulation strips work for everyone

Ovulation strips are another method commonly used to identify ovulation. These strips measure LH or a combination of LH and Oestrogen in urine.

The onset of the LH surge precedes ovulation by 35–44 hr, and the peak serum level of LH precedes ovulation by 10–12 hours. It usually occurs between midnight and early morning.

This marks the most fertile period of the menstrual cycle. Because this happens before ovulation, this is a prospective method that can detect ovulation ahead of time, giving you 24-48h for timed intercourse before ovulation.

There are qualitative and quantitative ovulation strips:

Qualitative: these strips tell you whether your LH value is below or above a certain threshold and will give you either a positive or a negative result. These strips don’t work for everyone – in fact they don’t work for about 1 in 10 women.3 Some of these strips interpret the results for you (digital tests), and show you a positive/negative sign or a smiley/sad face. Other strips only show a change in colour and you have to interpret the result yourself (have you ever found yourself wondering if the line is really there?), there is an added likelihood of error.

 Quantitative: these strips show a numeric measure of LH, usually in a concentration of mIU/mL. These tests will always tell you your LH value, regardless of whether your LH is low or high at baseline and during the surge. As not all women are the same, knowing what your normal is, can help you identify your fertile days with more accuracy. Mylo is one of these tests, that can tell you exactly your LH value, giving you a better understanding of how your LH is changing over time, what your pattern looks like and pinpointing your fertile window. 

Now that we have debunked some ovulation myths, what can you notice about your cycle and ovulation? Let us know in comments.

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