Making babies with the assistance of fertility drugs helps couples create
families, but do we really understand all the impacts of these treatments?
Sarka Lisonkova doesn’t think so. A post-doctoral fellow in the Dept. of
Obstetrics and Gynecology, she is launching the first population-based study in
North America to examine trends in use of the fertility drug clomiphene and its
impact on birth outcomes.
“There is extensive research on more invasive assisted-reproductive techniques
such as in vitro fertilization, but less is known about the effects of fertility
drugs,” she says. Research results will help prospective parents, health-care
providers and health-policy experts with decision-making.
Clomiphene, introduced in 1965, stimulates the ovaries to trigger release of an
egg. It is widely used to treat fertility problems such as those associated with
advanced maternal age (older than 35). Evidence from Europe suggests that such
fertility drugs may be the most significant contributor to increased rates of
multiple pregnancy.
“We don’t really know what’s happening in Canada but we do know the increase in
multiple births is being called a perinatal disaster because of the elevated
risk of pregnancy complications and problems for newborns,” says Lisonkova, a
trainee at Vancouver’s Child & Family Research Institute and a member of the
Women’s Health Research Institute.
Fetal, newborn and infant mortality rates are four to 10 times higher among
twins and triplets than single births, and cerebral palsy rates are at least
eight times higher. Pregnancy complications of multiple births include higher
incidence of pre-eclampsia or toxemia, gestational diabetes, low birth weight
and developmental difficulties. In addition, there is higher risk of the mother
dying.
There are efforts to regulate techniques such as in vitro fertilization to
ensure a singleton pregnancy. However, it is impossible to regulate the number
of eggs released during ovulation stimulation, which can result in multiple
pregnancy.
Assisted reproductive technologies of all kinds have led to an increase in
multiple births in Canada. The rate of twins increased by 50 per cent – from 19
per 1,000 in 1985 to 29 per 1,000 in 2004. The relative increase in triplet and
higher order multiple births has been more substantial, with the rate increasing
by 175 per cent from 42 per 100,000 births in 1985 to 115 per 100,000 births in
2004.
Lisonkova will use population-based pharmaceutical and health-related data to
evaluate clomiphene use among B.C. women from 1996-2006. The research will
capture data on approximately 1.1 million women aged 20-55 and a total of
360,000 births. Pregnancy and birth outcomes of women using fertility drugs will
be compared to those who conceive spontaneously, looking at issues such as
differences in occurrence of multiple pregnancies, congenital anomalies, preterm
births, newborn deaths, and miscarriage.
Although couples bear the costs of assisted reproduction techniques, including
fertility drugs, Lisonkova says the impacts of the drugs are a public issue
because the consequences of those choices are publicly paid for. Multiple Births
Canada, a national support group, estimates that health-care costs for one set
of premature twins is approximately $130,000 from birth to discharge. Costs
include more frequent pre-and post-natal monitoring, specialized birthing
procedures such as caesarean delivery and intensive care of newborns.
“We can’t control reproduction entirely and assisted reproduction is not always
the easy answer that some might think,” says Lisonkova. “Prospective parents
need to carefully evaluate the pros and cons of delayed childbearing and the use
of these powerful drugs.”
Research resources include BCPharmanet which collates data on all filled
prescriptions; Population Data BC that captures health and demographic data on
all residents; and the BC Perinatal Health Program database registry that has
information on all births at 20 weeks of gestation or more.
Lisonkova works with perinatal epidemiologist Dr. K. S. Joseph, UBC professor of
obstetrics and gynecology and a scientist at the Child & Family Research
Institute. Her research was funded by the Michael Smith Foundation for Health
Research.
Source : UBC Reports
