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As uncomfortable as it is for the expectant mother, morning sickness
may be nature's way of ensuring that the developing fetus gets the
proper nutrition. The nausea and vomiting so many women experience
during the first months of pregnancy may, paradoxically, nourish
their babies by keeping certain hormone levels in check. Researcher
found that women with morning sickness are less likely to suffer
miscarriages or have premature or low birth weight babies.
Several studies have shown that women with no morning sickness
symptoms have higher rates of miscarriage and underweight babies.
Still other research has suggested that women who eat high amounts
of carbohydrates early in pregnancy may have infants with lower
birth weights. The early calorie-restriction forced by morning sickness
may ensure that mothers-to-be channel energy to the developing placenta.
Animal research has revealed that there is greater insulin production
during early pregnancy. Insulin, which regulates blood sugar, is
released in response to food intake. Elevated levels of insulin
and insulin growth factor-1 (IGF-1) boost the mother's metabolism
of fat, at the expense of the developing fetus. By keeping food
intake in check, morning sickness controls these hormonal levels
and helps ensure that the fetus receives enough nutrients.
One reason morning sickness goes away after the first trimester
may be that IGF-1 becomes key to the fetus' growth later in pregnancy.
So, the suppression of IGF-1 and insulin is no longer a benefit.
Women who are underweight before pregnancy, she adds, may be less
likely to experience morning sickness because they need to accumulate
fat. Normal-weight women, on the other hand, typically have enough
body fat to make up for the nausea.
Obstetrics and Gynecology May
2000;95:779-782
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