September 15, 2011—While many older mothers have healthy birth experiences, the risks associated with pregnancy and childbirth start increasing at age 35 and rise significantly for mothers age 40 and older, according to a new study by the Canadian Institute for Health Information (CIHI). First-time mothers in their 40s are the most at risk for delivery complications. In Due Time: Why Maternal Age Matters examined more than one million hospital births from 2006–2007 to 2008–2009 and is the largest population-based study of its kind in Canada to measure the impact that advanced maternal age can have on both mothers and their babies.
When looking at complications associated with pregnancy, CIHI’s study found that mothers age 40 and older are at least three times more likely to develop gestational diabetes and placenta previa than younger mothers:
“Good prenatal care can help manage the risks associated with gestational diabetes and placenta previa and ensure a healthy delivery,” explains Dr. Mark Walker, Senior Scientist, Ottawa Hospital Research Institute; obstetrician, The Ottawa Hospital; and Research Chair in Perinatal Epidemiology, University of Ottawa. “It is important to understand the relationship with age in order to properly manage the risk.”
CIHI’s study also measured the risk of labour and delivery complications for older mothers. It found that two out of five (41.4%) mothers age 40 and older—and half (52.9%) of all first-time mothers in this age group—had Caesarean section (C-section) deliveries. In comparison, about one in three (35.3%) mothers age 35 to 39 and about one in four (25.2%) age 20 to 34 gave birth by C-section.
Assisted vaginal deliveries, such as those requiring the use of forceps or vacuum extraction, were also more common for older mothers with single births. More than one out of three (34%) first-time mothers in their 40s had an assisted delivery, compared with one-quarter (25.3%) of first-time mothers age 20 to 34.
“In Canada, almost one in every five births is to a mother over the age of 35, and this proportion is projected to continue to increase,” says Kathleen Morris, Director of Health System Analysis and Emerging Issues at CIHI. “While most of these birth experiences are healthy and happy, it’s important for expectant mothers, their care providers and health system planners to understand the risks associated with advanced maternal age.”
Advanced maternal age is widely known to be associated with chromosomal disorders, such as Down syndrome. Over the three-year study period, CIHI’s data showed that 1 out of every 127 babies born to a mother age 40 and older had chromosomal disorders, compared with 1 out of 370 babies born to mothers 35 to 39 and 1 out of 1,000 babies whose mothers were 20 to 34.
The risk of having a preterm birth (before the 37th week of pregnancy) is also higher for older moms. The study found that 1 in 13 babies were born prematurely to mothers age 20 to 34, compared with 1 in 11 in the 35-to-39 age group and 1 in 9 in the 40-and-older group. The hospital cost of a preterm birth is seven to nine times higher than for a full-term baby, according to 2005–2006 data from a previous CIHI analysis. Premature babies have not had the chance to develop fully in the womb and are more likely to face medical complications, ranging from difficulty breathing, vision problems and intestinal problems to neurological issues, such as cerebral palsy.
CIHI’s study found that the cost of in-hospital births increases with a mother’s age, rising from an average of about $2,900 for mothers age 20 to 34 to about $3,000 for mothers age 35 to 39 and approximately $3,200 for mothers 40 and older.
Average hospital costs for babies were also highest for those whose mothers were 40 and older, at about $1,800, compared with about $1,600 for mothers age 35 to 39 and approximately $1,500 for mothers age 20 to 34. These costs include care for birth defects, preterm births and small-for-gestational-age births. These estimates for both mothers and babies do not take into account any repeat hospitalizations or other potential medical costs associated with a health problem at birth. Physician and specialist fees are not included.
According to the study, the proportion of women 35 and older having babies varied across the provinces. Throughout the study period, more than 1 out of 5 (22.3%) babies in British Columbia were born to mothers age 35 and older, and a similar number (21%) of Ontario babies had mothers age 35 and older. In New Brunswick, about 1 out of 8 (11.8%) babies were born to mothers 35 and older, and 1 out of 10 (10.2%) babies in Saskatchewan had mothers in that age group.
CIHI’s study also showed variations in practice methods across the country. C-section delivery rates for women 40 and older were highest in Newfoundland and Labrador (47.9%) and British Columbia (45.6%) and lowest in Saskatchewan and Quebec (35.3% each) and Manitoba (34.1%). These variations are also reflected in women age 35 to 39. C-section rates for these women varied from highs of 41.4% in Newfoundland and Labrador and 37.8% in British Columbia to lows of 30.3% in Quebec and 28.9% in Manitoba. Women who deliver multiple babies have a higher chance of delivering through a C-section; therefore, they were not included in these provincial comparisons.
Established in 1994, CIHI is an independent, not-for-profit corporation that provides essential information on Canada’s health system and the health of Canadians. Funded by federal, provincial and territorial governments, CIHI is guided by a Board of Directors made up of health leaders across the country. Our vision is to improve Canada’s health system and the well-being of Canadians by being a leading source of unbiased, credible and comparable information that will enable health leaders to make better-informed decisions.