Nausea and vomiting in pregnancy: a review

Abstract

Throughout pregnancy, women with nausea and vomiting in early pregnancy showed a different metabolic pattern compared to asymptomatic pregnancies. Women suffering from nausea and vomiting seem to have a low "functional reserve" of their liver capacity and could tentatively be described as hypersensitive to estrogens or their metabolites, e.g., catecholestrogens. These steroids have "emetic" properties, which might be explained by their direct stimulation of area postrema. It is known that estrogens increase the brain's excitability. Another possible mechanism could be by interacting with liver metabolism, resulting in the production of irregular metabolites, which in turn possess "emetic" qualities.

PIP: The definition, history, incidence, diagnosis, possible etiology and treatment of nausea and vomiting in early pregnancy, also called emesis gravidarum, are reviewed. The condition may involve nausea, retching and/or occasional vomiting in early pregnancy: severe vomiting is termed hyperemesis gravidarum. The condition was described as early as 2000 B.C. It occurs in 50-70% of pregnancies in Western societies, but is said to be rare in some primitive societies. A lower incidence of nausea and vomiting has been associated with spontaneous abortion before 20 weeks gestation. Among selected hormones measured in pregnant women, those with nausea and vomiting in early pregnancy had significantly lower cortisol and progesterone, but higher hCG, while those with vomiting in late pregnancy had significantly lower testosterone and hCG and higher dehydroepiandrosterone than unaffected women. Other factors proposed as causative agents include tissue polypeptide antigen, high LDLs and VLDLs, and low HDLs, gall bladder disease, and ovulation from the right ovary. Women who develop nausea while taking oral contraceptives also have a tendency to do so in pregnancy. Possibly the steroid load on the liver may explain the condition. In the absence of a theory to explain nausea in pregnancy, no specific treatment is known. Experimental use of S-adenosyl-L-methionine, a methyl donor active in estrogen conjugation, reverses some estrogen-induced liver changes, such as cholestasis, pruritus, and bile acid abnormalities in pregnancy.