Estimated that 50-80% of pregnant women experience NVP beginning by the fourth week and often ending by the twelfth week after conception.
In up to 20% of pregnancies symptoms may persist throughout pregnancy.
10-15% of pregnant women receive drug treatment for nausea and vomiting during pregnancy.
Typically younger primagravida patients most prone.
Less common in circumstances known to be associated with diminished human chorionic gonadotropin, such as smoking.
More common in conditions of higher estradiol levels such as low parity and mole with theca lutein cysts.
More common in women with oral contraceptive-related sickness.
A genetic predisposition exists.
1-3% experience severe form of NVP called hyperemesis gravidarum, described as intractable vomiting associated with weight loss of more than 5% of prepregnancy weight, dehydration and electrolyte imbalances, which may lead to hospitalization.
Usually manifests early in pregnancy, with onset between weeks 3 and 8, with peak symptoms in weeks 7-12.
Most common in the first trimester of pregnancy, which is a period of rapid organogenesis.
Human chorionic gonadotropin-hCG levels peak at approximately 8 to 11 weeks after the last menstrual period, which coincides with the highest height of nausea.
Situations involving higher hCG levels such as multiple gestation, molar pregnancy, trisomy 21 are associated with more frequent and more severe nausea and vomiting of pregnancy, and estradiol may also play a role.
Antiemetic therapy coincides with the most susceptible time for teratogenic effects.
Ondansetron, the 5HT3 receptor antagonist most frequently used drug for nausea and vomitting of pregnancy and it is not associated with increased adverse fetal outcomes (Pasternak B et al).
Safe to use in pregnancy and not associated with increased incidence of congenital abnormalities.