Women who delay having children enter a ‘risk
zone’ of problems in their early thirties,
researchers say – much earlier than was previously
thought.
The risk of problems such as premature and
stillbirth rises by as much as 20 per cent for
women aged between 30 and 34, compared with
those having babies in their late twenties.
First-time mothers have previously been told they
are at high risk above the age of 35, but more and
more women are putting off having children until
their thirties.
Professor Ulla Waldenström, who led the study,
said: ‘To our surprise we found an absolute
increase in risk for negative effects on pregnancy
outcomes in the age group 30-34. These are
independent of the effects of smoking and being
overweight, which, when combined, lead to an even
greater risk.’
According to mail online in England and Wales the
average age at first birth was 27.9 years in 2011 –
up 1.3 years in a decade – and the average age of
all mothers was almost 30.
Some of the country’s leading obstetricians and
fertility specialists have warned that women who
put off having children until their thirties are
‘defying nature’ and may not become mothers at all
because of increased rates of risk and infertility.
Professor Waldenström’s team, from the Karolinska
Institute in Stockholm and the University of Bergen
looked at data from around one million first-time
mothers in Sweden and Norway.
They compared the results of pregnancy in first-
time mothers over the age of 30 with those aged
25 to 29.
First-time mothers have previously been told they
are at high risk above the age of 35, but more and
more women are putting off having children until
their thirties
The results showed that for women in their early
thirties, there was a one-fifth higher risk of giving
birth very prematurely – during weeks 22 to 31 of
pregnancy – or having a stillbirth. There was also a
higher risk that the unborn baby’s growth would be
restricted and that the baby would die.
First-time mothers in this age group were not
previously seen as at risk.
Smoking and being overweight pushed up the risks
of pre-term birth, stillbirth and neonatal mortality
to the same level as that for women aged 35-39,
said the report in the scientific journal Obstetrics
and Gynecology.
Professor Waldenström said: ‘For women
individually, the risk is small, but for society at
large there will be a significant number of
“unnecessary” complications with so many women
having children just after 30.
‘It would therefore be advisable to inform both
women and men, even at schools, of how
important age is to child birth.’
‘Biologically the best time is probably 20 to 30,’ she
added.
Prof Waldenström said many women wanted more
than one child, which meant the age of the first was
important.
She said the physiological effect of ageing on the
womb and placenta was likely to explain the higher
rates of complications.