Well thank you very much for inviting me. It’s a great honour to speak at a forum
like this which honours the legacy of such an admirable man as Brian Pridmore. Now, I’ve
come up with this slightly PC title, I thought ‘Later Reproductive Years’ might be a
bit more acceptable than ‘Advanced Maternal Age’. But I have to say, at this stage,
that things aren’t looking too good for Tamara, are they? She’s been to see Kelton
and he’s told her she’s left it way too late. And she’s been to see Erin and, despite
us doing that, her hypertension is out of control and she looks like she’s developed
some superimposed pre-eclampsia now. And someone has made the brave decision for induction
of labour. I see that’s been made already. And we’ll talk a little bit about that in
a moment. Now, I’ll just take a step back away from Tamara for a moment and talk about
South Australian women in general to say that we’ve had a lot of data given to us to see
if there is anything which confirms the very thing you would see if you sit in an antenatal
clinic. We’ve living in an age of profound demographic change in our obstetric population.
Aimee showed you, right at the start of the forum today, what a rise there is in women
of older age giving birth, and particularly, having first birth in South Australia. And
that is a big change. But I think the other change that we do see, it’s pretty obvious
to everybody, is the obesity in our population. It can’t be ignored; you can’t help but
notice generations of families coming in with obesity. And the sad thing is, and we all
unfortunately learn this, that age and obesity go together. And as we get older, we all tend
to get heavier as well. So we’ve got a double-whammy now in demographic change, and that is we’ve
got increasing maternal age, particularly women having their first baby, and, secondly,
we’ve got increasing maternal obesity. And I’d like to show you some data that will
give you some idea about the effect of these and I believe that these effects are cumulative
as well. So you might have one, you might have another, or you might have both, and
the worst combination would be to have both. Now, our patient, Tamara, here certainly has
the age and she’s overweight, without being obese. I think we said her BMI was 27 or something
like that. The other big change in our obstetric world is the increase in the rate of caesarean
section. In South Australia, we have one of the highest caesarean section rates in the
country. We also have, by the way, I might say, one of the highest rates in the country
of women over the age of 35 giving birth. Some of the data I’d like to show you in
a moment will put those two things together and give you a bit of an explanation as to
what’s cause and what’s effect. So let’s start with a bit of data. Now first of all,
I’d like to give you a simple message to take home, and my message to take home – and
I’m going to try and prove it to you as I go through – is that the rise in caesarean
sections in South Australia is principally due to demographic change and not to greed
of the obstetricians, not to the inconvenience of the obstetrician not wishing to be taken
out of bed in the middle of the night or away from the golf course, as is the belief, I
think, of a section of the community. But I’d like to show you that it’s due principally
to demographic change. And the physiological background to this is that data is now available
to show, to confirm, that the reduced ability to have a vaginal birth with advanced age,
or later reproductive years, or, in fact, if you are obese as well, is due to a decline
in myometrial contractility that occurs with age and occurs with increasing BMI. So there’s
a clear-cut physiological change. Now, there is some change. This data from
South Australia, from our wonderful South Australian Pregnancy Outcome Unit, and I’ve
been using principally the data from 2013, which is provisional and not yet released,
but I’ve been given this with permission from Wendy Scheil. Now, there is a rise in
elective caesarean section. Now, these are women having their first birth and as you
get older there is a greater rate of elective caesarean section. But when I looked at this,
I thought that’s probably still a surprisingly low rate of elective caesarean section at
16% for women over the age of 35. I might have thought it would be greater than that.
But certainly there is a rise in that. Now, the rest of my data, I’m going to exclude
these women who’ve have had an elective caesarean and talk about how women perform
in terms of labour because that’s my interest. And what happened in South Australia in 2013
if you were aged 35 or greater and you were having your first labour. These are women
who had a labour. Now 4 out of 10 would end up having a caesarean section. About 24% will
have an instrumental vaginal birth and only about 1 in 3 of women over the age of 35 would
actually have a normal vaginal birth. That’s over the age of 35, we’re not talking about
Tamara’s age of 47. About 1 in 3 over the age of 35 will end up having a normal vaginal
birth. How does this compare with younger women? Okay, here it is broken down by age
groups. So here’s age down this column here, 18 to 29, 30 to 34, 35+. If you’re 18 to
29, your chance of having an emergency caesarean in your labour is 27%. But if you’re over
35, as I said, it’s 40%. If you’re 18 to 29, your chance of having a normal birth
is about 50/50, 1 in 2, and if you’re greater than 35, as I said, about a 1 in 3 chance
of achieving a normal vaginal birth. So there is a change, with age, it’s not just that
everybody’s having caesareans, there’s a clear-cut change with age and it’s not
a matter of falling off the cliff when you become 35. These changes are incremental from
our optimal child birth age, which is somewhere less than 25, as the years go by, until your
fertility peters out completely. So there’s not a point at which suddenly you’re not
going to be able to have a vaginal birth. It’s incremental, your risk is incremental
as it goes along.
You’ve heard from Aimee about women over 35 and how the numbers of women in that group
having their first baby have gone up. By my calculation it was about 8% in 1999 in South
Australia and about approximately 12% in 2013. So the numbers are going up.
So research workers internationally have been looking at this rise in caesarean sections
and trying to see what it is behind it. And there’s a group who started in Scotland
as Gordon Smith moved down to Cambridge - he finished the work in Cambridge - but they
did a very nice study - and they’ve been very interested in maternal age – and they
did a very nice study where they corrected, they looked at caesarean sections in labour,
women having their first labour, and they corrected for every known confounding factor
that they had - maternal illness and any other factor you can think of – and they were
able to attribute 38% of the rise in primary caesareans from 1980 to 2005 in Scotland as
to be attributable to a rise in maternal age. And this, at the time when this came out in
2008, was quite ground-breaking. And they’re doing some other physiological research, which
I’ll show you in a moment. Simultaneously by the way, there is a group in Liverpool
who are doing very similar work but dealing with obesity. So they were looking at the
effect of obesity on birth outcomes. Smith has been looking at the effect of age on birth
outcomes. So a group of us got together, and several of the people involved in this publication
are here in the room, and also Steve Robson from ANU, and we looked at the South Australian
Pregnancy Outcome Unit data and did the same experiment using the SA Pregnancy Outcome
Unit data. What they did have there is data on BMI, which we didn’t have for our study
at that time. There’s better data available now on BMI, but for those years in South Australia,
it was either not collected or not very well collected BMI data. It’s being done better
now. And our conclusion, doing the same experiment here in South Australia, was that 75% of the
rise in primary caesareans in labour, for 1991 to 2009, were attributable to a rise
in maternal age. So I think we’ve got pretty good evidence that this isn’t the golf course
phenomenon, it’s actually something to do with a change in the demographics of the population
that we’re dealing with. Now, to back this up, there’s some terrific physiological
data. Now, the group in Scotland, and now in Cambridge, have been taking, with permission
of course, pieces of myometrium from women at caesarean section and conducting experiments
on these strips of myometrium to see how well they contract. And what they’ve shown here,
and this is looking at actually the strength of the contractions, as age goes up, the strength
of the contractions in these pieces of myometrium that they could induce went down, quite significantly
down. And furthermore, this graph on this side looks at under 30, 30 to 35, greater
than 35, looks at abnormal contractions - coupled contractions. And the rate of abnormal contractions
goes up dramatically as age goes on. So this lovely experiment shows that there’s a physiological
basis for the fact that women perform less well – “perform” is a bit of an awful
word, isn’t it; if someone can think of a better one – but outcomes of labour are
different as you get older and inferior as you get older. And if I may, although we’re
talking about age, but the obesity side goes with age, so I guess I’m entitled to do
this – look at these wonderful experiments done in the Liverpool group looking at uterine
contractility by BMI. So look at the contractions here – underweight, normal weight, overweight
and obese. Going like mad like this; here we are in the underweight – lovely looking
contractions just as we like and then normal weight are pretty infrequent and in the overweight
and it’s pretty hard to drum one up at all in the obese. And that’s confirmed by these
graphs here looking at amplitude of contractions and frequency of contractions they can induce
- underweight, normal weight, overweight and obese.
So I think from these experiments that have been conducted, you’d have to say that there
is something intrinsically different about the uterus of a woman who is over 35 and how
it behaves in labour from the uterus of a woman who is younger. So the old clock is
definitely ticking has been the pretty strong message today.
So just to drum it home to you again – that’s the message you want to say – the physiological
basis for reduced vaginal births with advanced age and obesity is because myometrial contractility
decreases with age and BMI.
Okay, so let’s go back to Tamara. Now, Tamara doesn’t quite fit the data I’ve been presenting
because she has had a baby before, although it was quite some years ago. If you’ve had
a baby before, the strongest determinant of the outcome of what your birth is going to
be in the next birth is what your birth was in the first birth. And principally, that’s
the influence of having a caesarean section in your first birth. That’s the biggest
driver of birth outcomes in subsequent births is if you’ve had a caesarean in your first
birth. So she had a normal vaginal birth, but a long time ago. So her uterus is still
going to be suffering the effects that we’ve talked about – about the declining myometrial
contraction with advancing maternal age, and she certainly is advanced in maternal age.
I can’t give you figures in South Australia for the birth outcome of a woman of 47 that
would be of any meaning because the numbers are so small as to not be able to have any
meaning attached to them. I’ve dared to provide you the data for women over 40, and
I think the number here was about 28 or something, quite small numbers of women over the age
of 40 in South Australia in 2013. But of that 28, this is over 40, half of them ended up
with a caesarean in labour and only about 3 out of 10 achieved a normal vaginal birth.
So if you ask me what advice would I be giving Tamara when she was found to have the uncontrolled
hypertension, superimposed pre-eclampsia at the age of 47, having her first baby. I think
what I would want to do with her would be to make sure that she was fully informed about
what she was getting into. Because I think it’s up to her to attribute the utility,
as they say, or how much meaning it has to her, to achieve a vaginal birth or not. And
I don’t think that’s a decision I can make about how important a vaginal birth,
a normal vaginal birth, is to her. But I think that she really ought to know that if she
does attempt a labour in this pregnancy, that the likelihood that she is going to achieve
a vaginal birth is probably going to be, at best, about 1 in 4. And the likelihood she’s
going to have a caesarean section is probably going to be at least 50% - that she’ll end
up with a caesarean section in labour. And I think it’s quite reasonable to inform
her of that information and let her make her own decision about whether or not the normal
vaginal birth would be so important to her as to go for that, what I would consider to
be, a relatively small chance. She might consider that to be a very acceptable chance at 25%.
So that’s the way I’d be dealing with her. So thank you very much for listening
to me.