In 2014, 49 year old actress Laura Linney welcomed a baby son, her first child with husband Mark Schauer. The couple married in 2009 when Linney was 45.

Falling pregnant in your forties – let alone 49 – is exceedingly rare. Except in Hollywood where it seems to happen with extraordinary regularity.

A few months ago, Halle Berry gave birth for the second time aged 47, to her daughter, Nahla.

Kelly Preston had her third child in 2012, age 48. Susan Sarandon had a baby at 46, and Beverly D’Angelo had twins (with 65yo Al Pacino) at 49. Holly Hunter also gave birth to twins at the age of 47. Geena Davis had her twins at 48, Jane Seymour had twins at 45, Marcia Gay Harden and Desperate Housewives’ Marcia Cross both had twins at 45 and Cheryl Tiegs had twins at 52.

The unspoken question of course is how. How did these women become pregnant so late in life when statistically, the chances of conceiving are miniscule if not zero? According to doctors, pretty much the only way to become pregnant in your mid to late forties is by using donor eggs.

Understandably, celebrities rarely announce the way they became pregnant unless a surrogate was involved (like with Nicole Kidman and Sarah Jessica Parker). When you’re famous, it’s impossible to hide the fact you weren’t pregnant. But something that is possible – and easy – to hide is HOW you became pregnant.

So how do so many famous women become mothers in their mid to late forties and even into their fifties? Donor eggs.

“Celebrities may be different from you and me, they may be better looking but one thing they’re not is more fertile” a Beverly Hills doctor told US Elle magazine. This doctor has helped several middle-aged stars have babies with donor eggs and describes it as the last taboo of infertility.

Famous or not, the most common cause of infertility in women is age. Too many of us simply leave it too late – for a whole bunch of reasons. Sadly, after a certain point there’s nothing you can do to increase the number of eggs you have or extend their expiry date.

“The chance of an egg resulting in pregnancy declines as a woman ages,” explains Brisbane obstetrician/gynaecologist Dr Brad Robinson. “The reason for that is that eggs age just like every other part of us. So an old egg that is finally released at the age of 45 may come out of the ovary – but as I like to tell my patients – it may well come out on a zimmer frame. This is evidenced by the fact the miscarriage rate climbs as we age from 12% at under 30 to 51% at ages 40-44.

The other problem for older mums is that the risk of chromosomal abnormalities also rises exponentially as women age. For example Downs Syndrome – a woman aged 20 has a risk of down syndrome of 1 in 1500. A woman aged 43 has a risk of 1 in 45.”

One of my friends had IVF a few years ago when she was 33 and was shocked to discover her fellow patients in the waiting room were all in their mid to late forties. “They looked visibly desperate,” she remembers. “It was so sad. I felt like saying ‘go home, save yourself the heartbreak.’ How could they believe anything would make them pregnant at that age? Then I picked up a magazine to see Geena Davis pregnant at 49 and I suddenly understood.”