Pregnancy is riskier for teens than adults


May 26, 2006|By JUDY FOREMAN

Is pregnancy riskier for teenagers than for adults?

Yes, according to Dr. Laura Riley, an obstetrician and director of labor and delivery at Massachusetts General Hospital. In general, the lowest-risk pregnancies are those in women between the ages of 25 and 35. At the extremes of age -- teenagers and women 40 and older, the rate of pregnancy complications increases.

Among other things, Riley said, teenagers are at higher than normal risk for pre-eclampsia, high blood pressure in pregnancy that, if untreated, can lead to coma and death. The treatment is often to induce labor because once the baby is born, the mother's blood pressure usually returns to normal.

Teen mothers are also more at risk for pre-term delivery because "teenage girls are more likely to have the worst diet in the world, make poor food choices, smoke, have more stress, and are less likely to be married," she said.

One reason that babies of teenage mothers often have low birth weight is that what few nutrients they do eat go to nourish their own growing bodies, not their babies'. As Columbia University researchers wrote in a study this year in the American Journal of Obstetrics and Gynecology, "much of the maternal nutrient intake supports maternal growth, to the detriment of the developing fetus."

The good news is that teenage pregnancy and birth rates have dropped by one-third since the early 1990s in all states and among all racial and ethnic groups, said Bill Albert, spokesman for the National Campaign to Prevent Teen Pregnancy, a private, nonprofit, nonpartisan group based in Washington. Research suggests that this is due to teenagers delaying sex and using contraception more reliably. Is the Body Mass Index (BMI) a good way to calculate heart disease risk?

It's not the best way. According to a major study published in late 2005, the waist-to-hip ratio is three times more accurate than Body Mass Index, or BMI, at predicting cardiac risk.

The BMI is a ratio of height to weight. If it's over 25, you're considered overweight. Over 30, and you're "obese." Both put you at increased risk of dying early from heart disease and cancer. (The government offers a BMI calculator at

Also, BMI can be misleading -- for example, very muscular people may get a high score, yet be at low risk.

To calculate your waist-to-hip ratio, get a tape measure and measure your waist, then your hips, then divide the first number by the second. For women, anything over 0.85 indicates increased risk, for men, anything over 0.95, said Dr. Arya Sharma an obesity specialist at the Population Health Research Institute at McMaster University in Hamilton, Ontario. He was also a co-author of the 2005 study, which involved 27,000 people, with and without heart disease.

The waist-to-hip ratio is more accurate because it reflects how much abdominal fat a person has. Abdominal fat -- the deep, visceral stuff that wraps around organs, is biologically active and secretes chemicals called cytokines that trigger inflammation in blood vessel walls, raise blood pressure, increase the tendency for blood to clot, worsen cholesterol levels and lead to a pre-diabetic problem called insulin resistance.

Put differently, it's possible to have a good BMI but be at risk.

"Don't fool yourself that if your BMI is 22, you're OK, if your waist-to-hip ratio is too high," said Sharma.

Dr. Thomas H. Lee, editor in chief of the Harvard Heart Letter, cautioned that it can be tricky to measure your hips in the right place. So you can just measure your waist. "If it's over 35 inches for a woman and over 40 for a man, you've got a lot of abdominal fat," he said. That means it's time to lose weight.

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