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The black hole in the British tabloid press left after the marriage of Prince William and Kate Middleton has been filled by the news that the princess is pregnant. The announcement of the birth, however, was forced by Princess Kate's hospitalization for a potentially deadly complication of the first trimester of pregnancy, hyperemesis gravidarum.
What Is Hyperemesis Gravidarum?
Hyperemesis gravidarum (hy-per-e-ME-sis grav-i-DA-rum) is sometimes called “morning sickness on steroids.” For the 1 to 2% of women who suffer it through the first and second trimesters and sometimes even the full term of their pregnancies, however, hyperemesis is far more serious than the much more common morning sickness.
Emesis refers to vomiting, and hyperemesis refers to frequent and voluminous vomiting. The term “gravidarum” refers pregnancy. Women who develop hyperemesis gravidarum suffer frequent and voluminous vomiting during pregnancy.
These unfortunate few expectant mothers may vomit morning, noon, and night, unable to hold down food at all. They may become dehydrated, and even if they are able to get enough fluids, they quickly become malnourished. Hyperemsis can result not just in severe discomfort, but even in miscarriage and the death of the mother.
How Hyperemesis Gravidarum Differs from Morning Sickness
Morning sickness is unpleasant but ultimately beneficial to the baby. Many of the chemicals that give food flavor are alkaloids that can damage the embryo's DNA. The piperine in pepper, the vanillin in vanilla, and even the caffeine in coffee and tea could, in extremely high doses, damage the developing child's genetic material and potentially cause birth defects.
To prevent genetic damage, a woman's body rejects foods that contain alkaloids. Since these are most of the “tasty” foods adults crave, pregnant women tend to get sick on normal diets, and tend to crave crazy combinations of foods, like pickles and ice cream, that stimulate the taste buds but don't contain chemicals a woman's body knows could harm the child. In most women, this protective mechanism turns itself off when the embryo has matured into a fetus less susceptible to genetic damage.
Not Just the Stomach
In hyperemesis gravidarum, a different process is at work. Early in pregnancy a woman's body makes large amounts of human chorionic gonadotrophin (hCG), the same hormone employed by diet doctors to accelerate weight loss. Too much hCG damages the thyroid gland, making the expectant mother's entire metabolism hyperactive. The nerves that serve as a pacemaker for the digestive tract also become hyperactive. As the mother starves, her body breaks down fat that "clogs" the liver.
Women whose bodies produce high levels of estrogen are at increased risk for hyperemesis gravidarum, as are women who have bad reactions to high-estrogen birth control pills.