By Dr Tomislav Meštrović, MD, PhD
Morning sickness (or pregnancy-related nausea and vomiting) represents the most frequent medical condition observed during pregnancy, with up to 80% of pregnant women experiencing this problem to some extent.
In a majority of cases morning sickness wanes after the first trimesterUp to 20% of pregnant women continue to experience symptoms until delivery. Prevalence of morning sickness is higher in multiple than in single gestations.
A severe form of nausea and vomiting in pregnancy is known as hyperemesis gravidarum and affects less than 1% of women.The condition can be debilitating, occasionally requiring hospitalization and rehydration. A number of studies have shown that women with morning sickness sufferpsychologically as well as physically.
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When does morning sickness occur?
For many women morning sickness represents one of the first signs of pregnancy. A number of misconceptions surround pregnancy-related nausea and vomiting. Although it is called “morning sickness,” it can actually occur at any time during the day. In fact, nausea and vomiting are limited to the morning in only 2% of pregnant women.
Some experts suggest that it should be renamed “morning, noon and night sickness” or simply “all-day sickness”. Several dictionaries still define of morning sickness as “nausea that occurs in the early part of the day.”. The phrase morning sickness as a sign of pregnancy can be dated back to 1793 (in Old English the word morgenwlætung was used).
“Sickness” implies dysfunction, yet vomiting during early pregnancy is observed in a majority of expectant mothers, with some researchers linking it to a lower risk of spontaneous abortion. One theory is that a nauseated woman may stay away from foods that can potentially harm the fetus.
A panoply of neuromuscular and metabolic factors have been implicated in pregnancy-related nausea and vomiting, but the exact cause remains elusive. Consequently, adequate treatment of this condition can be demanding, as targets for the treatment are still a question mark.
Other disorders that can cause nausea and vomiting in pregnancy
A majority of women with morning sickness exhibit normal vital signs and a normal physical exam . However, a cautious abdominal exam should be pursued to factor out peritonitis and other possible intra-abdominal causes of nausea and vomiting.
Although nausea and vomiting in the first trimester of pregnancy can be safely attributed to morning sickness, if abdominal pain, changes in bowel habits and bilious vomiting are encountered, other causes should be excluded.
Nausea with vomiting is the second most common indicator for performing upper endoscopy in pregnancy after bleeding from the upper gastrointestinal tract. Aminotransferase elevation could indicate chronic hepatitis.Elevation of serum glucose points to diabetes as an underlying diagnosis.
The differential diagnosis for morning sickness includes small bowel obstruction, peptic ulcer, gastroesophageal reflux disease, cholelithiasis, acute cholecystitis, pancreatitis, nephrolithiasis, appendicitis, gastroenteritis and hepatitis.
Reviewed by Catherine Shaffer, M.Sc.Sources
Last Updated: Aug 17, 2016