Having my son at age 36, I was made aware of the risks associated with my "advanced maternal age" pregnancy.
I never heard about any specific benefits. The only thing I knew for sure was that it was the right time for me.
But there are several evidence-based advantages associated with late-age births — for both mum and bub. And given women are increasingly having babies when they are older, obstetrician Nisha Khot says we should be talking about them more.
"In the medical profession we are very good at talking about risks [but] often not equally good at talking about benefits," says Dr Khot, who is the vice president of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG).
"It's not all doom and gloom."
Noa Sterling, an obstetrician gynaecologist based in the US, has a passion for demystifying long-held myths about older mums, and uses her social platforms to break down the research.
She says her role is to "turn down the dial" of fear for people who are pregnant later in life.
"Advanced maternal age doesn't automatically mean high risk … that's one myth that I think is still enduring."
Risks associated with advanced maternal age
Australian women are increasingly having children later in life.
Before 1991, only 5 per cent of first-time mothers were over the age of 35. By 2020, that figure increased to 17 per cent.
Before we get to the positives these mothers and their children may experience, it's important to acknowledge there are associated risks.
As we get older, Dr Sterling says we are more likely to have chronic medical conditions such as hypertension, diabetes, and thyroid disorders.
"Some of the risks are because people who are 35 [and older] are more likely to have other medical problems going on."
But even for healthy people, there are still some increased risks.
"That is mainly because there's an increased risk of chromosomal abnormalities, because as we age, our eggs — the DNA in our eggs — gets damaged," Dr Sterling says, adding that an embryo with a chromosomal abnormality is more likely to result in pregnancy loss.
Pre-term birth, pre-eclampsia, and gestational diabetes are other examples of health risks associated with later age pregnancy.
Dr Khot says the likelihood of a caesarean-section is greater.
"[That] may relate to pre-existing medical conditions like diabetes or pregnancy complications, or it may sometimes be maternal choice.
"Doctors would intervene if there was a medical or pregnancy complication and may, in some cases, recommend caesarean section as a safer birth option."
Australian research from 2017 found advanced maternal age was associated with a two-fold increased likelihood of birth by caesarean section in both nulliparous (not having given birth previously) and multiparous (having given birth previously) women.
However, the majority of these women birthed vaginally.
Women of advanced maternal age are at increased risk of stillbirth, but only if it's their first baby, explains Dr Sterling.
"If you are advanced maternal age, but it's not your first baby, you are actually at a lower risk of stillbirth than a younger person who's having their first baby.
"For whatever reason, stillbirth is much more common with first pregnancies than it is with subsequent [ones]."
And there is evidence that being older at the birth of a woman's first child is associated with an increased risk of breast cancer.
Chantel Thornton, a specialist breast cancer surgeon at Epworth HealthCare in Melbourne, says in the immediate period after giving birth, there is a higher index of breast cancer in all women.
"That risk is higher in women of mature age," she says, because "when you are older, you are already at increased risk of breast cancer merely by age alone, and therefore if you add the hormonal surge of pregnancy, your risk of breast cancer will be slightly elevated compared to women who have never had children."
However in advanced years, "when it is more common to get breast cancer in the 60s and 70s", Dr Thornton says the breast cancer risk is actually lower than for women who have never had children, indicating a protective factor later in life.
Maternal longevity and improved cognition
Several studies, including 2016 research involving more than 20,000 women, have found a link between late-age births and maternal longevity, but note a direct casual relationship cannot be established.
"[Research shows] later age at last birth, or giving birth at a later age, is associated with increased longevity, meaning you're more likely to have a longer life," Dr Sterling says.
"We see that people who give birth later on in life have longer telomeres, which are the non-coding end of chromosomes that help protect our chromosomes from degradation."
Basically, longer telomeres mean cells can divide more often before deteriorating or dying.
Researchers aren't sure if people who are able to have children later in life were always going to have longer telomeres, or if pregnancy later in life makes it that way, explains Dr Sterling.
"I wouldn't be so quick to dismiss [the latter] because we know that the DNA from our children stays with us always, and we know that it can actually help our body repair itself."
On DNA, Dr Sterling says there is research showing women who have more male DNA from being pregnant with a boy may have lower rates of dementia.
And she says more generally, there is some evidence women who have been pregnant later in life may have better cognitive function.
"That may be because in pregnancy, your progesterone [and] your estrogen get like 20 to 40 times higher than it is pre-pregnancy," Dr Sterling says.
"That big hormone load may actually be protective for cognitive function."
It all sounds positive, but Dr Khot says we should consider "we don't [always] know the extent to which other underlying factors contribute to these beneficial effects rather than pregnancy alone."
Those underlying factors may include needing to staying active and engaged for longer — just to name two possibilities.
"You could imagine if you are having a baby when you are older, a toddler is going to be active, so you will have to be active [for longer]," Dr Khot says.
"Once your child goes to school you will be helping them, using brain cells for longer."
She adds health benefits may also come down to women having babies later in life being more financially stable than younger mums, and therefore more able to invest in healthcare.
Reproductive epidemiologist Rui Wang from the University of Sydney says while promising, the above research should be interpreted with caution.
He says there are a lot of factors after birth that can impact longevity and cognition, for example, but are not addressed in the above studies.
Some of the cohorts used, for example from the 1990s, may also not be applicable to the current population, Dr Wang says.
Much of the research also looks at age at the birth of someone's last child, as opposed to their age when having their first.
"All this kind of evidence, it's very promising," Dr Rui says, but adds further research needs to be done to paint a clearer picture.
Academic and health benefits for kids
Children born to older parents may do better in school, be healthier, and have fewer social, emotional and behavioural issues, says Dr Sterling.
"And we see this still when we control for socio-economic factors," Dr Sterling says of research in this area.
Researchers can control for socio-economic factors by collecting data on relevant aspects like income, education level, and occupation, and then statistically adjusting the analysis to account for potential influences of these factors on the study outcome.
Dr Sterling says that could indicate we get "better at parenting as we get older", regardless of what money or education we have access to, for example.
"It's too bad that our peak fertility is really 18 to 31."
For example, a 2012 study published in the British Medical Journal found language development in children was associated with improvements with increasing maternal age.
The same study also found children of older parents were also less likely to present to the emergency room with unintentional injuries.
A 2016 study published in the European Journal of Developmental Psychology found older maternal age was associated with fewer behavioural, social and emotional difficulties in children at age seven and at age 11 (but not at age 15).
Fertility and pregnancy risks separate issues
Dr Sterling says the information she shares isn't about encouraging women to wait longer to have babies. But to support those who, for whatever reason, have become pregnant later in life.
"It's really important for us to continue to raise awareness and to talk about the fact that fertility declines as we age; we see quite a significant drop-off in fertility in the late 30s and certainly 40 plus.
"But once that individual is pregnant, rather than just fearmonger and scare them about all of the things that they're increased risk for, talk to them [and say] there's benefits to this pregnancy for you and for this baby."
Dr Khot says it is useful to focus less on age, and more on the individual.
"There are risks that go with a teen being pregnant, and [risks with] being 48 and pregnant, and benefit in both."
