The rate of premature births is creeping upward in Canada, which researchers say is putting newborn babies at risk and is more costly to the healthcare system.

A new study by the Canadian Institute for Health Information says more than 54,000 babies were born prematurely or small for their gestational age (SGA) between 2006 and 2007. For the year studied, this represented one in seven of the approximately 350,000 babies born in Canada annually.

Jean-Marie Berthelot, vice-president of programs at CIHI, said that changes in the ages and behaviours of expectant mothers may be contributing to an increase in preterm births.

"In Canada and throughout North America, we've been seeing a gradual decline in the number of babies born small for their gestational age, and an increase in the rate of preterm births," he said in a statement.

"Factors such as delayed child bearing and use of reproductive technologies are likely contributing to a greater number of multiple births and preterm deliveries; while a lower smoking rate, for instance, may be contributing to a decline in babies born underweight for their age."

Snapshot of preterm baby births

In the 2006-2007 year studied, the Canadian preterm birth rate was approximately 8.1 per cent-- a figure CIHI said computes to some 29,000 total births.

The preterm birth rate has increased since the early 1990s, when it was once 6.6 per cent.

CIHI reported that premature babies are more likely to be born from older mothers.

In the year studied, nearly 10 per cent of mothers aged 35 and older had preterm births, compared to only eight per cent of mothers between 20 to 34 years of age.

Mothers in this older age range had a variety of factors that impacted their risk levels, the CIHI study said. Those factors included the impacts of biological aging and the use of reproductive technologies in conceiving.

These mothers are also more likely to have multiple births, chronic diseases such as diabetes and hypertension and to experience complications during delivery, the study said.

Teenage mothers were also likely to give birth to preterm babies as a result of various risk factors -- low pre-pregnancy weight, inadequate nutrition, improper prenatal care, etc. -- they are often exposed to. Studies have shown that mothers in this age group are also more likely to abuse alcohol or drugs, which also can increase the risk of giving birth prematurely.

The CIHI study also found that women with hypertension or diabetes were up to six times more likely to give birth to a preterm baby as compared to their healthy peers.

Another major risk factor for premature births were babies who were one of multiple fetuses -- according to the study, multiple-birth babies were 17 times more likely to be born preterm as compared to their single-birth peers.

According to the study, Alberta (8.7 per cent) and Newfoundland and Labrador (8.6 per cent) had the highest preterm birth rates amongst Canadian provinces, while New Brunswick and Prince Edward Island had the lowest (7 per cent each). Nunavut had the highest overall rate (10.8 per cent).

Snapshot of SGA baby births

An SGA baby is defined as a baby who is smaller than nine in ten babies of the same gestational age.

Dr. Jan Christilaw, an obstetrician at B.C. Women's Hospital in Vancouver, told CTV News that these SGA babies some of the most vulnerable children born in Canadian hospitals.

"Those are the babies that for any age that they're born at, they're born below the 10th percentile for growth," said Christilaw, explaining the SGA definition.

"They tend to be the sickest babies."

In the 2006-2007 year studied by CIHI, about 8.3 per cent of all single births were SGA births.

This represented about 28,000 total births, the CIHI report said.

CIHI says this has decreased from a rate of about 11 per cent in the early 1990s.

According to the new CIHI report, Teenage mothers were most likely to give birth to an SGA baby, in part because their teenage bodies are not as physically mature as their older peers. These younger mothers were also likely to give birth to an SGA baby for all of the same reasons they were more likely to give birth to a preterm baby.

The CIHI study found that mothers with hypertension were about twice as likely to give birth to an SGA baby, while those with diabetes were not distinguishable from their non-diabetic peers when it came to SGA birth rate.

Mothers living in urban areas were 30 per cent more likely to have an SGA birth, while those living in low-income neighbourhoods were 50 per cent more likely to have SGA births than mothers in high-income neighbourhoods.

Ontario (8.9 per cent) and Alberta (8.7 per cent) had the highest SGA birth rates in Canada according to the CIHI data. Newfoundland and Labrador (5.9 per cent) and Prince Edward Island (6.8 per cent) had the lowest.

Costs of preterm, SGA births

The CIHI study found that early births are very costly to the health care system.

The study reports that the birth of a single preterm baby will result in nine times the healthcare costs involved with a single full-term baby birth. In the case of a multiple birth, a pre-term baby will incur seven times the healthcare costs of a full-term baby.

In the case of SGA babies, their births cost slightly less than twice that of non-SGA babies.

Caroline Heick, director of acute and ambulatory care information services at CIHI, said in a statement that both of these birth groups "are at an increased risk of long hospitalizations and complications" -- hence the increased cost to the healthcare system.

"It is important to understand the risk factors for expectant mothers in order to provide better prenatal care and better plan for appropriate services to offer these babies the care they need," she said.

Christilaw said she has concerns about the implications of the CIHI study.

"What worries me most about this data is that we're continuing to see an increase in preterm births in this country -- and it's gone up almost 25 per cent over the last 15 years," she told CTV News.

"The reason that's important is that babies born preterm, that brings with it significant health concerns and it also brings significant implications in terms of health care costs."

The B.C. doctor said these earlier-than-expected babies need significant medical care well past their time in the delivery room.

Christilaw said such babies "will be in hospital longer and they'll be away from their families longer, they'll be tied into the system longer in terms of as we watch their development over the years."

With a report from CTV medical correspondent Avis Favaro and senior producer Elizabeth St. Philip