Diabetes Is a Risk in Pregnancy That Carries Risks Beyond

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Routine Screening

Gestational diabetes, which affects about 4 percent of pregnant women, usually occurs midpregnancy, by the 28th week of gestation. Though its causes are unclear, there are some clues, namely placental hormones that suppress the action of insulin in the mother. This can result in insulin resistance: the mother’s pancreas continues to spew out insulin but her body’s cells fail to use it properly to process blood sugar, causing sugar levels to rise in the mother’s blood.

This extra sugar, though not the mother’s insulin, crosses the placenta and raises the baby’s blood sugar level, giving the baby more energy than it needs to grow normally. The result is macrosomia, a “fat” baby often too big to be born naturally without injury to the baby, mother or both.

The baby’s pancreas, stimulated by sugar from the mother, may produce extra insulin, resulting in low blood sugar at birth and an increased risk of breathing problems. These babies are also more likely to become obese children and diabetic adults.

In addition to an added risk of diabetes later in life, a woman with gestational diabetes can develop high blood pressure during pregnancy and may need a Caesarean section to deliver an overly large baby.

Women are at higher than average risk of gestational diabetes if they are overweight, older than 25, have a strong family history of diabetes, have had gestational diabetes during a prior pregnancy, have previously given birth to a baby weighing nine or more pounds, or have been told they are “prediabetic” with blood sugar levels higher than normal. The risk is greater in African-American, Asian and Hispanic women than in Caucasians.

A pregnant woman is unlikely to know her blood sugar is running high unless she is tested. For those with risk factors, a screening test for blood sugar should be done at the first prenatal visit, Dr. Metzger said.

Women not at high risk for gestational diabetes should be tested between weeks 24 and 28 of pregnancy. In this screening test, now routine in prenatal care, the woman swallows a concentrated solution of glucose, and her blood sugar is measured an hour later.

If the result is abnormal, a fasting test for blood sugar is next. After about 14 hours of no food or drink other than sips of water, the woman is given another dose of glucose, and her blood levels are measured hourly for three hours. If those levels are abnormal on two or three measurements, the woman is said to have gestational diabetes, though some doctors think even one abnormal level is a bad sign.Continued...

Diabetes Is a Risk in Pregnancy That Carries Risks Beyond

By JANE E. BRODY

Elise Bloustein, always slender and healthy, was 38 when she became pregnant with her first child in 1990. Her joy was tempered by the results of tests that revealed two problems: anemia and gestational diabetes, which Ms. Bloustein believes may have been caused by stress associated with the deaths of her parents.

Regardless of the cause, the conditions required close attention to what she ate. The doctor sent her to a nutritionist who put her on a diabetes diet and told her to self-test her blood sugar levels several times a day. The goal was to keep her blood sugar from spiking by eating lots of fiber-rich foods and limiting simple and refined carbohydrates.

Frequent sonograms were done to monitor the baby’s growth and prevent a stillbirth, a risk of gestational diabetes. Ultimately, the baby was born normal and healthy, weighing seven pounds. But Ms. Bloustein was cautioned that gestational diabetes could recur in a future pregnancy (it didn’t) and that she was at high risk of later developing mature-onset (now called Type 2) diabetes.

“So far, 18 years later, there’s no sign of diabetes,” Ms. Bloustein, now 55, said in an interview. “But it’s very much in my mind, and I watch my diet and my weight and have an annual physical.”

In the years since Ms. Bloustein’s first pregnancy, the incidence of gestational diabetes has nearly doubled, a result of the rise in prepregnancy weight among American women, Dr. Boyd E. Metzger, an endocrinologist at Northwestern University Feinberg School of Medicine, said in an interview. At the same time, much has been learned about the disorder and its possible effects on newborns and their mothers.

It is now known, for example, that even small blood-sugar abnormalities can cause trouble.

A seven-year international study directed by Dr. Metzger, which was released last year at the American Diabetes Association’s annual meeting and published in May in The New England Journal of Medicine, showed clear links between blood sugar levels and pregnancy outcomes, even when the mother’s sugar levels are not high enough to be called diabetes.

The study, which followed the pregnancies of more than 23,000 nondiabetic women, revealed that as blood sugar levels increased during pregnancy, the risk of having a baby too large to be born vaginally rose too, as did the baby’s chances of being born with low blood sugar and high levels of insulin.

“At levels well below what we would consider to be diabetes, we’re seeing morbidity,” reported Dr. Robert Ratner of the Georgetown University Medical School in Washington.

The study found a continuous increase in risk as the mothers’ blood sugar levels rose, with no cutoff point below which the risks were minimal.Continued...