The Beckhams are about to welcome their fourth child into the world, rumoured to be a girl, after three sons - Brooklyn, Romeo and Cruz.
So what's it like to swap muddy football boots and dinosaurs for all things pink - and how far will parents go to try to improve their chances of having the boy or girl they long for?
When Karen started trying for a third baby after two boys, she jokingly asked her doctor for tips on conceiving a girl.
The doctor joked she had heard a rumour that the nursery rhyme "What are little girls made of? Sugar and spice, and all things nice," had had positive results.
Karen admits that, somewhat unscientifically, she started eating a sugar lump every morning, encouraging her partner, Rob, to do the same.
"Neither of us wanted not to eat it in case there was some truth in the nursery rhyme," she wrote in her blog.
"We were both prepared to get very fat, have grotty teeth and a boy baby! Once I was pregnant we stopped eating sugar lumps."
They decided not to find out the baby's sex until after the birth. As it turned out, they were granted their wish.
"When she was born, we were both obviously delighted but my main concern was whether she was breathing, did she have 10 fingers and toes et cetera," Karen says.
"At the time my desire for a healthy child certainly was stronger than my desire for a girl."
Other mothers have strong feelings about having one sex or the other.
Heather had her daughter, Lily, after three sons. She admits to being "devastated" when she found out, at her 17-week scan, that she was having a girl.
"It hadn't been planned, but I felt that as long as I was having another boy I would cope," she says.
"I felt that I was pregnant for the first time again, carrying this alien being. I didn't know what to prepare for.
"All the little girls I knew were manipulative, evil creatures hell bent on mental torture and showing off.
"Boys, I know - mud, bundles of energy and heart-on-sleeve personalities. No hidden motives or emotions."
Two years on, Heather says raising a girl has been the source of constant surprises.
"We didn't do it, didn't force [toy] irons and babies on her, but yet with identical parenting she is this strongly feminine creature.
"She loves make-up and having her toes painted, she fusses over her brothers, interfering and coddling them.
"She twists them round her every whim, bats her lashes and sings in a crystal soprano that makes them smile at tiny girly perfection.
"Although I am the same species I don't recognise this different being quite yet.
"Sixteen years of boys, Pokemon, dinosaurs, Scooby-Doo et cetera is ingrained too deep. But we are enjoying getting to know her."
Experts say little boys and little girls are much more similar than parents think.
According to Dr Helen Barrett, developmental psychologist and research fellow at Birkbeck College, University of London, studies suggest even when baby boys and girls are lying in a cot kicking their legs at the same rate, boys are seen as more energetic.
And a newborn boy's cries are seen as more forceful and may be responded to quicker, even when there is actually no difference.
"If you dressed a little boy in pink no-one would be any the wiser," say Dr Barrett.
Physical differences, which are slight in the early years, are outweighed by the expectations of parents and peers, she says.
"No matter how hard you try to make boys not be boys and girls not be girls, they tend to pick up a lot of stereotypical things from their peers.
"Parents can get quite disgruntled about things like boys playing with guns.
"It's a big thing psychologically for parents to have children of different sexes rather than just one sex.
"Usually the difference in sex ties in with a lot of your own experiences, hopes and expectations."
For Janine, 38, from York, having a baby girl was a chance to splurge on pink. After four boys and a string of miscarriages, she thought she would never have a girl.
"I would have been more than happy with another boy," she confesses. "I didn't think I could have a girl anyway.
"I went a bit pink mad and even now she is 16 months old I can't resist a pretty pink dress. Everything is pink from carseat to high chair!"
Despite the abundance of pink, her little girl has defied gender stereotypes.
"She is always filthy - five minutes after having a bath - and she is very rough and tumble. However she is also a woman in practice in that she is a stroppy little madam!"