How do we know that inadequate weight gain is
so important in Colorado?

In 1999, the Colorado Department of Public Health and Environment
conducted a population-attributable risk analysis for the first time using
all 166,591 births between 1995 and 1997.

The report is called Tipping the Scales: Weighing in on Solutions to the
Low Birth Weight Problem in Colorado.

Since many factors have an impact on Colorado’s low birthweight rate,
it is challenging to determine which factors exert the largest effects.
Some medical factors are closely associated with low birthweight. For
example, low birthweight is closely associated with abruptio placenta;
about half of all births complicated by abruptio placenta are low weight.
However, not many women (fewer than 350 per year) experience this
condition, and therefore, abruptio placenta accounts for a very small
proportion of low weight births in the state. Many of the medical factors
are manifested in only a small number of women. Even though the low
birthweight rates in these groups are high, their contribution to overall low birthweight is small.

What does the Tipping the Scales report say about:
Low birthweight, altitude, weight gain, and
smoking?

Low birthweight can be attributed to a number of factors:

Multiple gestation is the largest risk, accounting for approximately 20% of the
State's low birth weight rate.

• 1 in 5 low weight births is a multiple.
• The LBW rate would drop by almost 20% if there were no multiple births.
• The increase in LBW in the 1990s and early 2000s is partly due to assisted reproductive
  technology (ART) and older mothers.
• 3.2% of all Colorado births are multiples (2004 data), up from 1.9% before ART.

Among singleton births:

• The #1 factor is inadequate maternal weight gain during pregnancy.
• The #2 factor is smoking during pregnancy.
• The #3 factor is premature rupture of membranes.
• The #16 factor is altitude over 10,000 feet.

back to top

• High altitude is the perennial explanation for low birthweight in Colorado;
  it is a well-documented association.
• All of Colorado's births occur above 3,000 feet elevation.
• There is a 1-ounce loss in birthweight per 1,000 feet elevation.
• Altitude is just one among a number of reasons why Colorado's rate is high.
• If Colorado was not a high altitude state, it would still have a low birthweight
  rate that ranked in the middle of all the 50 states. There is a lot of room for
  improvement.
• Altitude is a fixed factor and not something that can be changed.
  Therefore, efforts in Colorado need to be directed toward modifiable
  risk factors such as weight gain and smoking cessation.

back to top

Colorado compared to other high altitude states
Healthy People 2010 Goal is 5.0%

Colorado has a much higher low birthweight rate than other states with
mountainous regions.

Weight Gain

• One out of every four pregnant women in Colorado gains less than the
  recommended amount of weight during pregnancy.
• The fact that inadequate weight gain is so common makes it a major
  contributor to the number of low weight births.
• Women with inadequate weight gain increase their risk of having a low
  birth weight baby by at least 50%.
• Twenty percent of women in Colorado are considered to be underweight
  prior to pregnancy, and these women are at even greater risk for gaining
  inadequately.
• The singleton LBW rate could drop by nearly one percentage point if all women
  adequately gained weight.

Smoking

• Low birthweight link is well-established.
• Smokers using fewer than 10 cigarettes per day predominate.
• Cessation, not reduction, removes the risk.
• The singleton LBW rate could drop by nearly one percentage point if no
  pregnant women smoked.

back to top

Last update: November 23, 2005
All information provided is for informational purposes only and does not constitute medical advice.