9 fertility myths

30th November, 2021 • 7 min read

Fertility is still an area shrouded in myths and misconceptions.

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As a recent survey of 1,000 people, commissioned by Healthily revealed, there’s still a degree of confusion about how lifestyle factors such as smoking and weight can affect your fertility, when exactly you can get pregnant in a monthly cycle, and whether men have a biological clock or not.

More than a third (36%) of the 1,000 men and women polled believed men did not have a biological clock and 30% wrongly believed females couldn’t get pregnant during a period. A further 57.8% wrongly believed an egg has a 2-day window to be fertilised after it’s released, (it’s only 24 hours).

Find useful information on getting pregnant with our

complete Guide

9 Fertility Myths

Here we bust some of those myths and sort out what does (and doesn’t) affect your fertility.

1. Smoking doesn’t affect fertility


has several important effects on fertility in both male and female partners, so it’s one lifestyle change to consider if you’re trying for a baby.

A review of 6 studies of 10,823

males (5,257 smokers and 5,556 non smokers) found smokers were more likely to have a
low sperm count
(also known as oligozoospermia) and had a higher rate of misshapen sperm.

Another study showed male smokers have a lower chance of their partner getting pregnant through assisted reproduction techniques, such as

in vitro fertilisation (IVF)

When it comes to the effects of smoking on female fertility, there’s evidence that it can affect ovarian reserve – the medical name for the number and quality of eggs in the ovaries.

The chemicals in tobacco can speed up egg loss and lead to earlier


2. Men don’t have a biological clock

False. Yes, they do. While it’s true men can remain fertile all their lives and father children in their 70s and beyond, their fertility does decline with age.

This was confirmed in a review of 90 studies of 94,000 men in 2015, which found increasing male age was associated with significant declines in semen volume, percentage of motile sperm (swimmers) and normal shape, although not sperm concentration.

Another study also found that women with older partners have a higher rate of


3. All women have a 28-day cycle and ovulate at day 14

False. If you’re trying for a baby, you may think it’s only worth having sex in your fertile window (5 days before ovulation when an egg is released by the ovaries and 24 hours afterwards).

But contrary to popular belief, only 16% of women have a cycle that is 28 days long. That’s according to one of the largest studies ever conducted on menstrual cycle length, which analysed data from a menstrual cycle tracker and ovulation calendar mobile tracker (with 1.5 million users). It’s well documented that ovulation happens exactly 14 days before your period starts, but the study also found that this can vary a lot – from as little as 5 to up to 35 days before. Although, most women will ovulate 13 to 16 days before their period starts. The authors of the study said this had important implications for women trying to conceive.

It’s now recommended that you have sex every 2 to 3 days to

maximise your chances of getting pregnant

4. Being overweight or obese doesn’t affect your fertility

False. Being

or obese does affect both male and female fertility. Fertility is lower in females who have a higher
body mass index (BMI)
. Studies have shown that male sperm quality is also affected by
through a variety of mechanisms, including hormonal changes.

5. You can always rely on IVF to have a baby – even if you're in your 40s

False. While the media is full of stories of older celebrities having babies in their 40s and even 50s, what they often fail to mention is that many of these are born with donor eggs from younger women, or even via surrogacy.

UK figures show live birth rates for

patients under 35 were 32%, per embryo transferred, compared to below 5% for patients who used their own eggs and were over the age of 43.

The good news is that live IVF birth rates are improving for women in their mid to late 30s:

  • for women having IVF aged 35 to 37 and 38 to 39, live birth rates have risen from 6% in 2019 to 25% and 29% respectively in 2019
  • using donor eggs does increase the live birth success rate to more than 30% for all age groups having IVF
  • only 17% of patients aged over 40 used donor eggs in 2019

6. You can’t get pregnant on your period

False. Although it’s unlikely you’ll get pregnant during your

, it can happen. This is because sperm can live between 5 and 7 days in the body and if you ovulate soon after your period, those surviving sperm could fertilse an egg. There’s no ‘safe’ time to have unprotected sex during your cycle, just times when it’s more likely you’ll get pregnant.

7. Male cyclists may have fertility problems

Maybe. A study by Boston University found that 32% of cyclists in a study had low sperm count and fewer mobile sperm compared to less than a quarter of men who didn’t exercise.

The authors concluded cycling more than 5 hours a week was associated with reduced sperm concentration.

However, the study was based on men who were about to start

fertility treatment
, so the findings might not be applicable to the wider population.

Researchers also found men who undertook a 16-week low to moderate intensity cycling training course had reduced sperm quality.

8. Women are just as fertile in their 20s as in their 30s

False. Fertility is ageist. There’s actually quite a big difference between female fertility before the age of 35 and beyond. Healthy couples with no fertility problems have a 1 in 4 chance of getting pregnant in their 20s per menstrual cycle, and this drops to 1 in 10 by the age of 40. This is because the

quality and quantity of female eggs decline as you age
, and around 1,000 eggs die per month. By the age of 37, 90% of the eggs a female is born with will have died.

9. Some sexual positions increase your chances of getting pregnant

Maybe. There’s no research on this, but logic tell us that positions that allow deep penetrative

(such as the missionary position) may increase the likelihood of conceiving. It’s thought this is because sperm is ejaculated further up the vagina.


Understanding your fertility, how your cycle works, and the influences of lifestyle factors such as smoking and obesity on both males and females, plus the importance of age, can help you maximise your chances of conceiving.

If you’ve been trying for a baby and haven’t conceived within a year or within 6 months if you’re 35 or older, talk to your doctor for advice and fertility tests.

Key takeaways

  • smoking affects male sperm count and female egg reserve
  • only 16% of women have a cycle that is 28 days long and only 13.8% of women ovulate on day 14
  • live birth rates for IVF are much higher if you are under 35
  • healthy couples with no fertility problems have a 1 in 4 chance of getting pregnant in their 20s, and this drops to 1 in 10 by age 40
  • you can get pregnant when you’re having a period

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.