Myth: Whether you have morning sickness or not sure pregnancy can determine the baby's gender.
Fact: Most experts believe this is truly a myth. However, several studies have found that among women with severe morning sickness bad enough to require admission to the hospital, slightly more than half (53% to 56%) delivered girls, so perhaps there is some truth to this idea. Then again, even among those with the worst morning sickness, the male and female offspring were nearly 50-50 and whether this applies to milder cases is unknown.
No one knows exactly why morning sickness (also known as hyperemesis gravidarum) occurs, though it has long been thought to relate to elevated hormone levels (including progesterone, estrogen and/or human chorionic gonadotropin, or HCG). Which hormone, if any of these, is most important, remains a matter of speculation, and several other theories have been proposed such as zinc deficiency, genetic factors and psychological factors. At least one study found that women carrying a female fetus had higher HCG levels than with a male fetus. If true, that could explain the connection.