Separating fact from fiction about having a baby in your 40s.

When actress Cameron Diaz, 47, announced the birth of her first child Raddix this month, the first question was about her age.

“She’s in her late 40s though”, asked the world’s armchair experts.

Everyone was shocked that a woman of her age could carry and deliver a healthy baby into this world.

While we’re on the topic…here’s some things pregnant people never say. Post continue after podcast.

Of course, we don’t actually know how Cameron and husband Benji Madden welcomed their tiny human into the world.

But they certainly aren’t the only ones whose baby news has been intertwined in recent years with comments about their age.

The same question was asked of TV host Sonia Kruger, who had daughter Maggie aged 49 in 2015, as well as singer Alanis Morrisette, who had her third aged 44 last year, and musician Janet Jackson who had a son aged 50 in 2017.

As women, we've always been told the optimal age to have a child is in our 20s and 30s - with 35 being the magical number when our fertility starts to decline more rapidly.

But the reality is, women are having babies later nowadays. It's a trend that started in 1999, as documented by the Bureau of Statistics, when for the first time ever there were more women over 30 having children, than those in their 20s.

Now, the average age for women to have a baby is 31.3.

Dr Katrina Rowan is a fertility specialist, reproductive endocrinologist, gynaecologist and reproductive surgeon.

Mamamia's news podcast The Quicky quizzed her on the facts about having babies later on in life.

You can listen to the full podcast here, which includes a chat with Maxine, a 40-year-old first-time mum. Post continues after podcast.

Here's everything we learnt from Dr Rowan.

After you turn 35, do the risks associated with physically carrying a baby increase?

"While many women over the age of 40 are able to carry a healthy normal pregnancy to term, there are some increased physical risks.

"Early on, there's an increased risk of miscarriage. It's estimated in their 40s women have a 50 per cent chance of miscarriage each time they conceive.

"When the pregnancy gets past the first trimester, there is double the risk of preeclampsia for women over 40.

"There is also an increased chance of diabetes-related to the pregnancy and placenta problems such as a low placenta.

"Many of these risks are manageable if they're detected early enough, but [it's important to note] pregnancy is a stressful state on the cardiovascular system. Most women in their 40s have enough cardiovascular reserve to be able to cope with this. But an increased stress might become an issue for women in their 50s and beyond.

"Because of this, most Australian doctors would recommend an upper limit of 50 to 52 for a woman to actually carry a pregnancy."

Are you seeing an increase in mums in their 40s?

"Yes. I certainly am.

"This is reflected in the Australian Bureau of Statistics, which show the number of women giving birth between the ages of 40 and 44 has tripled over the last 30 years."

Are there benefits in being an older mum?

"There are benefits. Firstly, the mother's likely to have attained a higher level of education which has benefits for her. This has also been linked to numerous benefits for a child's development.

"The mother is likely to be in a more financially stable position, and they also have more life experience and are more likely to be emotionally mature which may help them cope with the demands of parenting."

If you've been taking the pill, does that mean you've got more eggs to play with once you stop?

"Unfortunately not.

"There is no stopping the decline of egg numbers, whether a woman is on the pill or not.

"It's actually a three month process for an egg to come out of its storage form and develop to the point of ovulation.

"The pill only stops the final step of this development. So it doesn't stop the number of eggs coming out of the reserves each month."

Can we help the health of our eggs as we age?

"The main issue with egg health in older women is the number of eggs that don't have the right amount of chromosomes. This is very hard to change.

"There are a couple of other aspects of the egg quality such as the egg's ability to produce energy and grow once it's fertilised.

"There is some research ongoing into egg supplements that is trying to help this aspect of the quality, but unfortunately there's nothing that's been proven a benefit as yet. The research is still in its early stages.

"I will add, poor lifestyle choices such as cigarette smoking can reduce the quality and the numbers of eggs that a woman has. So maintaining a healthy lifestyle can mean that at least a woman is not doing any harm beyond the effects of age."

Is it safer now to have a child in your 40s, compared to past decades?

"There have been great advancements in the detection of chromosomal abnormalities during pregnancy, so it's less likely that these sorts of problems would be missed.

"There's also been some developments in the prevention of preeclampsia and the management of gestational diabetes.

"They would all filter down to make it safer to be pregnant at this age."

What's your advice for women in their 40s who want to conceive?

"If it's something you really want, the risks are generally manageable. So go for it.

"For a woman in her early 40s, I would recommend starting as early as you possibly can, because every month can count at this stage.

"When you start trying to conceive, maintain a healthy lifestyle, see your GP for advice regarding vaccination and pre-pregnancy tests and seek advice for optimal timing to conceive.

"I'd also advise that a woman doesn't wait too long to seek advice from a fertility specialist if she's having trouble, it's generally recommended that a woman sees a specialist if they're over the age of 37 and have had six months trying with no success.

"A woman should seek help even earlier if she has irregular periods."

What about for women nearing 50?

"For women in their mid to late 40s, my main advice is to remain open to the possibility of egg donation.

"[At this age] it's extremely difficult for women to conceive with their own eggs either naturally or with IVF.

"Many who do conceive in this category would have had the assistance of a donor egg."