UBC Reports | Vol. 50 | No. 9 | Oct.
Becoming a Mum after 35
A UBC researcher wonders if we really know the risks of
By Hilary Thomson
As the mums and strollers roll by, it’s obvious that
more women over the age of 35 are having babies. In fact,
there has been a 83 per cent increase from 1991 to 2000 for
babies born to Canadian mothers over 35, according to the
Canadian Perinatal Health Report, 2003.
In addition, many women wait until they are over 35 to have
their first baby and a UBC researcher wonders if we know as
much as we need to about the risks of delayed childbearing.
PhD student Sarka Lisonkova has launched a two-year study
to look at impacts of delayed childbearing in B.C. It is the
only population-based study in North America to examine trends
in pregnancy outcomes as well as individual risk, multiple
births, and newborns’ need for health-care services,
in both rural and urban settings. She will compare statistics
for mothers over 35 with those for mothers aged 20-35 years,
and will also examine the whole spectrum of age categories.
“Women aren’t really told of the biological
disadvantages -- particularly for the first baby,” says
Lisonkova, who had her first child at 28. “There’s
no arbitrary deadline for births, but risks do start to accelerate
in later years.”
As reproductive organs age, function appears to diminish,
says Lisonkova, and points to research that wanted pregnancies
occur less frequently after the age of 35.
However, research findings vary as to risks posed by increased
Some studies report greater risk of pregnancy complications
such as premature delivery, stillbirth and low birth weight.
Some risks might decrease, however, if mothers have already
had a first child before the age of 35 years.
Other studies have reported no association between age and
outcome when factors such as obesity, illness and prior reproductive
problems are taken into account. Lisonkova will review the
effect of such risk factors as smoking and fertility problems
in her research.
In B.C., birth rates have dropped over the last five years
for all age groups except mothers aged 35 years and older,
who give birth to approximately 8,000 babies annually.
B.C. has the second highest proportion in Canada of live
births to mothers over 35 years and the highest proportions
for those 40-44 years.
Lisonkova is eager to find out at what age reproductive
risks significantly increase and how risks may change over
the decade 35-45.
“Maybe as new generations are getting healthier and
living longer, the reproductive system functions quite well
for longer,” she says.
“Or maybe this is true only for certain groups of
women who stick to a healthy lifestyle and are free of illness
or complicating conditions.”
Lisonkova says B.C. offers the opportunity to create a uniquely
comprehensive study, thanks to resources offered by the B.C.
Linked Health Database and the B.C Perinatal Database Registry.
These databases allow her to study health services used by
large population groups and link them to complete obstetrical
data for approximately 200,000 births during the period 1998-2002.
Using this and other B.C. vital statistics data, she will
plot and compare a 10-year trend in health service use for
babies of both older and young mothers.
Lisonkova believes that her study will help guide planning
for maternal/infant health services and that differences between
rural and urban areas may reveal valuable information to help
allocate resources in the province. Findings on individual
risk may assist physicians and other health-care professionals
to recognize risks during prenatal care and delivery and will
aid prenatal counseling and planning.
The study is supported by the Centre for Healthcare Innovation
and Improvement, located at Children’s & Women’s
Health Centre of British Columbia, an agency of the Provincial
Health Services Authority. Funding for this research comes
from a senior graduate studentship awarded by the Michael
Smith Foundation for Health Research.