During the first trimester of pregnancy, many women experience the bouts of nausea
and vomiting known as morning sickness.
Despite its name, morning sickness can occur at any time, day or night. It usually
begins around the 6th week of pregnancy, peaks around week 9, and disappears by weeks
16 to 18. Although unpleasant, morning sickness is considered a normal part of a healthy
pregnancy.
But what's not normal is when morning sickness becomes so severe that
a woman persistently vomits several times a day, loses weight, and becomes dehydrated
or at risk for dehydration.
When this rare pregnancy-related condition is left untreated, it can interfere
with a woman's health and her baby's ability to thrive.
About Severe Morning Sickness
The medical term for severe morning sickness is "hyperemesis gravidarum" (which
means "excessive vomiting during pregnancy"). It usually follows a timeline that is
similar to morning sickness; however, it often begins earlier in the pregnancy, between
weeks 4 and 5, and lasts longer.
Although some women with severe morning sickness feel better about halfway through
their pregnancy (around week 20), some continue to experience it throughout the entire
pregnancy. Often, the symptoms become less severe as the pregnancy progresses.
Most of the time, hyperemesis gravidarum occurs during a woman's first pregnancy.
Unfortunately, women who experience it in one pregnancy are more likely to experience
it again in later pregnancies.
Causes
The cause of severe morning sickness is unknown. Research suggests that it might
be related to hormonal changes that occur during pregnancy. Specifically, a hormone
called human chorionic gonadotropin, or HCG, might be to blame because the condition
primarily occurs when HCG is at its highest levels in a pregnant woman's body.
Severe morning sickness also might be hereditary because it is more common in women
whose close family members (such as mothers and sisters) have had it.