Here's what science says about how you can conceive a boy or girl

Is there a way you can scientifically plan to conceive a boy or girl? Yes. It's all about biology, timing intercourse and doing so in relation to ovulation.
Is there a way you can scientifically plan to conceive a boy or girl? Yes. It's all about biology, timing intercourse and doing so in relation to ovulation.

Gwinyai Masukume from the University of the Witwaterstrand and Victor Grech at the University of Malta published a study that only recently got our attention: More sex during South Africa’s World Cup meant more boys nine months on.

I wondered, is that something I can scientifically measure? Can I hope and pray for a boy or girl and then follow specific methods that can make it happen?

Well, it wasn’t just a freak shift that resulted in the disproportionately higher number of male babies born in early 2011. And although it may not have been calculated, it certainly wasn’t random.

There’s research and science behind the conception of a boy that says all the little Ronaldos and Messis had much to do with the excitement and adrenaline when daddy’s team won, the romantic strolls through the fan parks that followed, and a subsequent trip to the hospital, some 9 months later. 

Sperm motility and sex – factors that affect conception

In their study, Masukume and Grech wrote that there were two factors which led to this increase: sperm motility and when, and how frequently, people had sex.

“When people have sex more often, on average more boys are born," they write. "This relates to the fertile period of a woman’s menstrual cycle. If conception takes place at the beginning or the end of the fertile period, the child is more likely to be a boy. If it takes place in the middle of the fertile period, the child is more likely to be a girl.”

On the contrary, “in terms of sperm motility,” they continued, “the consequence of negative natural events is that sperm motility is low. This translates into fewer boys being born.”

They explain that, with particular events such as the World Cup, people tend to feel strong emotions. In this case it was happy emotions that had male sperm swimming faster, making their way to their prize quicker, and fertilising the egg.

The make-up of the male and female sperm cells

Fertility expert Toni Weschler elaborates in her book, Taking Charge of Your Infertility, on the make-up of the male and female sperm.

Referencing Dr. Landrum Shettles, famous for the "Shettles Method", she explains the male sperm cells (carrying the Y chromosomes) are smaller, lighter, faster and more fragile than the female sperm cells (carrying the X chromosomes), which are thought to be bigger, heavier and slower, but more resilient.

So timing intercourse as closely to ovulation as possible has a better chance of conceiving a boy because a healthy male sperm cell will probably reach the egg first.

But if you have sex, say, four days after ovulation, your chances of conceiving a girl is higher, because the male sperm cells would have expired while the female sperm cell may be resilient enough to make it all the way through. 

Conceiving a boy vs. a girl

Here are the factors and scenarios that may therefore increase your chances of a boy or girl, according to Toni Weschler’s research and supported by scientific studies.

WARNING: This doesn’t mean these methods are sure-fire. Also, it goes without saying, that both genders are beautiful blessings that we're grateful for!

conceiving a boy and girl infographic

So you’re more likely to have a boy if…

  • You have sex on your peak day (the day you are most fertile) or the day after. Your peak day usually occurs the day before you ovulate or the day of ovulation itself.
  • You use artificial insemination (AI), as the procedure is usually done as close to ovulation as possible. 
  • You’re younger. Younger men generally have a higher sperm cell count, increasing their chances of a male sperm cell reaching the egg, while younger women have more copious, alkaline-quality cervical fluid, which also favours the conception of boy.
How to conceive a boy

You’re more likely to have a girl if…

  • You have sex 4 to 2 days before your peak day.
  • The male has a low sperm count. It could occur naturally or due to certain factors such as heat, particular drugs and toxic substances which kill many male sperm cells, according to Shettles. It is for this reason that anaesthesiologists, for example, who are exposed to certain substances throughout their career, are thought to father more girls.
  • The male is under stress. Men with careers that subject them to environmental stresses, such as a shift in atmospheric pressure, varying oxygen tension, possible radiation, or even excessive scrotal heat from tight-fitting clothes, are more likely to have girls as their fragile male sperm will not be able to survive the stress. Stress from one’s personal life can also result in low sperm motility.
  • You use in vitro fertilisation, as researchers speculate that more female sperm cells are capable of surviving the stresses of the procedure, which can be quite rigorous.
How to conceive a girl

Much to do with timing

So the sex of your baby really does have much to do with the timing of intercourse in relation to ovulation, the stress levels of the dad and environmental exposure, as well as fertility interventions. 

As for deliberately determining the sex of the foetus before implantation in fertility treatment, in March 2012, the Minister of Health passed regulations relating to the National Health Act of 2003 to make social sexing officially illegal in South Africa.

It’s considered ethically wrong, as people fear it might normalise selecting the sex of your baby and encourage ‘designing’ children. 

That being said, the research stands, and so does the science.

So if you look up and see your son, you might also be getting flashbacks of one overly funny doctor, cracking a joke in the delivery room, at just about the worst time.

"Feel it. It is here."


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