While the state and county health departments acknowledge that altitude can decrease birth weight, the agencies don’t consider it a modifiable factor, unlike other variables associated with restricted fetal growth.

“A lot of people will come to us and say, ‘I’m going to have a small baby, because I live at altitude,'” said Michelle Wilson, a public health nurse manager at the Summit County Health Department.

“But there are things we can do to combat that.”

Sue Ricketts, of the state health department, agreed:

“There is a grand desire to attribute low birth weight to altitude, because in a way that takes the burden off of us. But we really need to take responsibility for our health.”

Ricketts pointed out that high altitude regions also exist in Utah, but the state’s low birth weight rate is much lower than Colorado’s, though fewer people live at high altitude in Utah and the Mormon Church helps keep residents well-nourished.

Others are skeptical of an approach that discounts altitude.

“The problem with ignoring the altitude effect, as some people have been inclined to do, is that you’re not as well-equipped to treat the problem,” Moore said.

Researchers have studied the effects of altitude on pregnancy for decades.

On average, every 3,300 feet of elevation gained reduces fetal weight by about 3.5 ounces, according to a 1997 study in Colorado.

So in Summit County, with an average elevation of about 9,000 feet, babies could on average be born about 10 ounces lighter than those born at sea level.

The percentage of low birth weight infants increases by around 50 percent from the lowest elevations to the highest elevations in the state, the study showed.

Local pediatrician Dr. Chris Ebert-Santos said most newborns she sees in Summit County are born around 6 pounds, instead of the national average of 7-8 pounds.

Premature babies aren’t born more frequently at altitude than at sea level; fetuses at altitude just grow more slowly than those at lower elevations, said Lorna Moore, a professor at the Altitude Research Center at the University of Colorado at Denver and Health Sciences Center, who co-authored the 1997 altitude study.

Some mechanisms of altitude’s contribution to low birth weight are understood and documented, but much of the explanation remains elusive.

“The reason that babies grow more slowly, we think, is that there is less oxygen available in utero,” Moore said.

But exactly what that reduction in oxygen does to the growing fetus is still under question.

In Summit County, more women develop pregnancy-related blood pressure issues and preeclampsia than at lower altitudes, which can affect fetal growth, said Dr. Julie Gelman, an obstetrician-gynecologist with High Country Health Care.

Gelman also sees inadequate weight gain, smoking and other factors than contribute to low birth weight.

“It’s so rare that people with no other risk factors have a small baby just because they live here,” she said.

Pregnancy-related altitude effects in Colorado can be difficult to document, because a relatively small portion of the population lives at 8,000 feet or above ” where the effects really begin to kick in.

But studies in more heavily populated and even higher elevation regions, such as Bolivia, have demonstrated that altitude exudes a very real influence on fetal growth.

For example, studies controlling for other factors, including smoking, socio-economic status and preeclampsia, have associated altitude independently with low birth weight.

In places like Bolivia, where only about half of newborns receive medical care, the consequences of high altitude pregnancy can be devastating, Moore said.

Bolivia has one of the highest infant mortality rates in the Western Hemisphere.

In Colorado, where few people live at elevations as high as those found in Bolivia and quality medical care is abundant for both mother and baby, the effects of altitude on pregnancy may not be as significant as other factors, such as inadequate weight gain.

But that doesn’t mean it’s an easy road for babies born at 9,000 feet.

Altitude and newborns

It would be difficult to attribute Caden Kennedy’s low birth weight solely to altitude.

But altitude did play a major role in his first eight weeks of life. Like at least half of infants born in Summit County,

Caden’s low oxygen saturation after birth required him to be placed on full-time oxygen during that time.

A developing fetus receives oxygen through the placenta at a lower concentration than exists in the air, pediatrician Ebert-Santos said.

When a baby is born and takes its first breath, the higher concentration of oxygen in the air sparks a process that converts the baby’s lungs into breathing machines.

At altitude, babies typically receive enough oxygen just after birth, because even up here, the oxygen level in the air is considerably higher than the baby is accustomed to in the womb.

But between a day and two weeks later, the baby’s oxygen saturation often begins to dip, and the baby starts needing supplemental oxygen to make a smooth transition into the world.

Most babies acclimate within two months.

Some of them don’t.

Liliana Grace Head was born May 7 at Summit Medical Center.

After birth, her oxygen saturation began to drop, and her physician placed her on oxygen.

Liliana’s parents, Erin and Brandon Head, who lived at 9,800 feet in Breckenridge, were prepared for the oxygen.

But at Liliana’s two-month check-up, her oxygen saturation had dropped to 73 percent, falling considerably short of the normal level of 89-93 percent.

At that point, conversations with their pediatrician shifted from oxygen supplementation being helpful for the newborn, to the possibility of long term consequences from an oxygen deficit, such as heart murmurs and pulmonary problems.

The Heads sprung into action, selling their house and moving to the low altitude state of Minnesota.

Within 45 minutes of landing in Minnesota, Erin brought the baby to the doctor to check her oxygen levels: 97 to 99 percent.

“Problem solved,” Brandon said.

Only a small percentage of babies don’t acclimate to the conditions at altitude. But there’s no guarantee which ones will.

“It is a gamble as to whether the kids can handle it,” he said.

So what’s being done about the low birth weight problem?

Colorado has two programs working to combat the low birth weight rate.

The Nurse-Family Partnership, a national program serving first-time mothers of limited income in Summit and several nearby counties, is designed to improve pregnancy outcomes and child health and development, and increase families’ economic self-sufficiency.

Of babies born in 2006 to women participating in the program, 9.5 percent were low birth weight ” about a 10 percent improvement over Summit County’s rate.

Another program, the Healthy Baby Campaign, created in 2004 by the state health department, seeks to educate providers and pregnant women about the necessity of gaining an adequate amount of weight and quitting smoking during pregnancy.

Historically, a quarter of Colorado women failed to gain an amount of adequate weight during pregnancy, said Michelle Hansen, dietitian and program coordinator for the Health Baby Campaign.

But this year’s numbers marked improvement, sliding to 18.7 percent.

The program encourages providers to focus on the needs of women who are underweight or normal weight pre-pregnancy and to use the Institute of Medicine guidelines for adequate weight gain.

“It’s really important for women who are considering pregnancy to discuss their specific risk factors with their physicians,” Hansen said.

They should also talk to their providers about weight gain during pregnancy.

For more information about the Nurse-Family Partnership, go online at: http://www.nursefamilypartnership.org.

For more information about the state’s Healthy Baby Campaign, go online at: http://www.healthy-baby.org.