Skip to content

Why are more boys than girls born every single year? – BBC News

By Philippa Roxby
Health reporter, BBC News

Every year, there are always more baby boys than girls born in England and Wales. Fact. Why?
Since records began in 1838, the cries of babies born every year have been predominately male.
In not one year, stretching back to the start of Queen Victoria's reign, have girls outnumbered boys at birth.
In 2017, in England and Wales, for example, there were 348,071 live male births and 331,035 live female births – a difference of roughly 17,000.
And that higher tally of males compared to females born each year is a pattern that has repeated itself for nearly 180 years.
In fact, a ratio of roughly 105 male births for every 100 female ones is generally seen as natural and normal.
It is fairly consistent around the world, although in some countries like China and India the gap is wider because male offspring are more desirable.
More surprisingly, it is a ratio that has been known about since the 17th Century.
But why this ratio exists is not yet completely understood – although there are several theories.
The first theory is an evolutionary one which says that in order to have an equal number of males and female in adulthood, there have to be slightly more males born.
That is because being a male is a dangerous thing. Males are more likely than females to die in childhood and at all stages of life – from accidents, taking risks, suicide and from health problems.
"At every age, in almost every time and place, a man is more likely to die than a woman," says Prof David Steinsaltz, associate professor of statistics at the University of Oxford.
So more males than females at the start of life should mean equal numbers of men and women in adulthood, so the theory goes.
In fact, adult women always end up slightly outnumbering adult men in the UK, according to Office for National Statistics figures – and living longer.
There are lots of different factors that could determine whether a male sperm (carrying a Y chromosome) or a female sperm (carrying an X chromosome) is first in the race to fertilise the woman's egg.
These include the ages of the parents, the woman's ovulation cycle, levels of stress, diet and sexual position.
One popular theory is that the odds of having a girl increase by having sex several days before ovulation and then abstaining so that the female sperm, which live longer, but swim more slowly than male sperm, outlast their counterparts.
Conversely, if sex happens closer to ovulation or after it, the best swimmers get to the egg first and boys are produced.
Parents may swear by these techniques, but scientists say there is little evidence they make any difference.
There is also some research which suggests parental stress could lead to the birth of more girls, while living through wars and conflicts may give rise to more male conceptions.
If planning that sexual encounter does not have an impact on a baby's sex, then could something else be happening during pregnancy?
If there are equal numbers of female and male-producing sperm and roughly equal numbers of conceptions, then more female foetuses must perish to give males the upper hand.
Some research suggests females are more likely to be lost in the womb during early pregnancy, but other studies have shown males foetuses are more fragile later in pregnancy and lead to more stillbirths.
Scientists say it is hard to pin down what actually happens and the reasons why.
What we do know is that more male conceptions reach term and more boys are born.
Why does Sweden have more boys than girls?
The success of sperm 'down to rhythm'
Why men might want to eat more nuts
The secret shame of having no sperm
ONS stats – birth tables for England and Wales
ONS – UK population estimates
Germany decides who will take charge after Merkel
The election race could barely be tighter as voters decide who will run Europe's biggest economy.
'EU and UK will have to work together as friends' Video
Chinese tech executive freed by Canada comes home
Simple guide to German election ending Merkel era
Xi Jinping's socialist ambitions for China
Why are there still so many nuclear weapons? Video
How to measure a shrinking glacier. Video
Your pictures on the theme of 'new beginnings'
In love with the Resistance: My mother-in-law's war
What needs to be agreed to stop climate change?
The wonders of Somali cuisine and a taste of home
The surprising everyday words that should never be spoken
Lyrics quiz
Have you been getting these songs wrong?
Feeling hot
What happens to your body in extreme heat?
Germany decides who will take charge after Merkel1
Taliban hang bodies as warning in Afghan city2
Chinese tech executive freed by Canada comes home3
Billie Eilish and Ed Sheeran join 24-hour concert4
Usyk beats Joshua by unanimous decision5
Rwanda genocide 'kingpin' Bagosora dies in prison6
Hauliers and poultry workers to get temporary visas7
Airport closed as La Palma volcano intensifies8
Top Huawei boss flies back to China after deal with US9
In love with the Resistance: My mother-in-law's war10
© 2021 BBC. The BBC is not responsible for the content of external sites. Read about our approach to external linking.


Leave a Reply

Your email address will not be published. Required fields are marked *