July 22, 2008
Tuesday

ANCHORAGE, Alaska -- Alaska infants are twice as likely to be born with major birth defects as infants in the U.S. as a whole, according to a new study by the state Department of Health and Social Services -- and officials are at a loss to explain why.

All races of Alaskans exceed national rates for "major congenital anomalies," according to the review of seven years of data (from 1996 through 2002) drawn from the Alaska Birth Defect Registry.

But rates were especially high among Alaska Natives, for whom birth defects were reported in 10.5 percent of all live births, compared to 6 percent for all Alaskans. Among white Alaskans the rate was 4 percent. Among all Americans the rate was 3 percent.

Alaska public health officials have long suspected that infants there suffer higher rates of birth defects, said Janine Schoellhorn, an analyst in the state's Maternal and Child Health Epidemiology unit. But previous evidence was limited and the number of birth defects varied substantially from year to year.

"This is the first time we've been able to produce estimates that we are confident in publishing -- because we now have several years of data," Schoellhorn said.

Congenital heart problems lead all other types of birth defects in Alaska, just as they do nationwide, the study reported. Chief among those were defects involving holes in the heart.

But Alaska also posted higher than average rates of less common birth defects, such as cleft palates (two times the national average), fetal alcohol syndrome (four times the national average), and Hirschsprung's Disease, characterized by enlarged colons due to bowel obstructions (six times the national average).

Grouping the major birth anomalies into broad categories, the study found that Native Alaskans were twice as likely as the state's non-Native population to suffer a cardiovascular birth defect -- but 17 times more likely to exhibit a "fetal alcohol spectrum" disorder, such as growth delays, behavioral problems or facial abnormalities.

Only about one in 10 of the fetal alcohol spectrum cases leads to a specific diagnosis of Fetal Alcohol Syndrome, or FAS, in which all three of the spectrum characteristics are present, Schoellhorn said.

The high incidence of birth defects among Alaska Natives can't be quickly explained away by identifying a prevalence of high-risk factors, such as drinking or smoking during pregnancy or conceiving at an advanced age, according to Dr. Bradford Gessner, a pediatrician who heads the state's Maternal and Child Health Epidemiology unit.

The study identified those behaviors in birth certificate reports, then weeded them out for controlled comparisons. Doing so only reduced the birth-defect prevalence among Alaska Natives from 2.6 to 2.2 times that of white Alaskans, Gessner said.

"What this is saying is that even independent of differences in cigarette smoking, alcohol consumption and maternal age -- which is a well-known risk factor for birth defects --Alaska Natives still have an increased risk ... that we don't really know how to explain," he said.

The study noted that some birth defects are genetic in origin, while others might be influenced by behaviors or environmental factors. The causes for most birth defects are unknown.

But a correlation between birth defects and a mother drinking or smoking during pregnancy is well established. And earlier research in Alaska demonstrated that supplementing a mother's diet with vitamins containing folic acid succeeded in reducing the incidence of neural tube birth defects by about half, especially among Native Alaskans.

"We saw a large Native/non-Native disparity that was completely eliminated after fortification with folic acid," Schoellhorn said.

Some of the high incidence of birth defects in Alaska -- such as the numbers for Hirschsprung's -- came as a surprise to health officials, Schoellhorn said. Specialists who study Hirschsprung's in the Lower 48 have since notified the state to express their desire to study Alaskans with the disease.

The study also found instances of birth defects, such as Down syndrome, that occur at about the same rate in Alaska as they do in the rest of the U.S. (There were 15 cases of Down Syndrome per 10,000 live births in Alaska between 1996 and 2002, compared to 14 cases per 10,000 live births in the U.S.)

The state health department recommends that women of childbearing age take a daily multivitamin containing 400 milligrams of folic acid and avoid alcohol and cigarette use during pregnancy. It also suggests that pregnant women consult with a health care provider prior to taking any medications and avoid any drugs or environmental health threats that can interfere with the development of a fetus.

Birth defects are considered the leading cause of infant death and childhood disability nationwide, resulting in more than $2.5 billion a year in hospital costs. In Alaska, birth defects contributed to a third of all neonatal deaths during 1992 and 2002.

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