Ultrasound has made it possible to look inside the womb, and for the first time in human history we have been able to see whether there is a girl or boy in there.
For most of us, that means knowing what clothes to buy, or what names to pick. But in some countries the impact is much less benign.
In 2006, British medical journal the Lancet estimated that in the previous two decades, in India, 10,000,000 female foetuses had been aborted simply because they were female.
As recently as last Saturday, Toronto's Star newspaper detailed birth rates in the Punjab region, where for every 1,000 boys born alive, there are only 793 girls.
In China, with its one child policy, the same problem exists but figures are harder to come by.
And now, there is a new test that can tell you the gender of your child, not at 18 weeks or thereabouts, which is where ultrasound does the job, but at eight weeks - when a termination is much easier to obtain.
It is revolutionary, and it is available now in New Zealand for $127, nearly three times its price in the US.
But do we need it? How reliable is it? And how does it work?
It is called Intelligender, and it works like a pregnancy test. You use your first urine sample of the day, syringe it into the container provided and wait 10 minutes to find out if you are having a boy or a girl.
If the urine turns dark green or black, you are having a boy. But if it stays the same - yellow or dark orange – it is a girl.
David Portnoy distributes the test here in New Zealand. He says it is 90 percent accurate, and a few simple rules will stop it going wrong.
But the test is not without its critics. It has been available across the Tasman for five months, the Australian Medical Association making its concerns clear.
"Are people going to use this to choose the sex of their baby very early in pregnancy, and if it's not the sex they desire, are they going to be seeking a termination?" asks the association's Rosanna Capoling.
Critics here agree.
"That would be horrifying because a) it's not a good reason to start with, and secondly early pregnancy is such an emotional time, it's a really difficult time to make decisions about anything," says Richard Fisher, Fertility Associates.
Mr Fisher says women should not make any decisions based on the test.
"People need to know this is not a serious test, not a test you could ever make a sensible decision on. In fact, I wouldn't even paint the colour of my room based on this test."
But Mr Portnoy dismisses any issues in Australia and doubts there will be any here.
"There's no statistical evidence in Australia, certainly none in the US, to support the fact that Intelligender is available in the market place is adding to any statistics the government might put out on any subject."
The test kit has a 90 per cent success rate, meaning one in ten results will be wrong but Portnoy says Australian research reinforces its accuracy.
“We have tested 150 women since May, giving a 91 per cent accuracy if you take the test between 15 and 19 weeks”.
But Richard Fisher says 90 per cent is not enough.
“I think it's not very good science, because most serious scientists wouldn't accept 90 per cent as a serious scientific outcome. I think this is the frivolous use of not very good science”.
Intelligender is so confident in their test, they are offering your money back if the test is wrong, but you have to wait until the baby is born to find out for sure.