Merck Manual

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Some Causes and Features of Nausea and Vomiting During Early Pregnancy

Some Causes and Features of Nausea and Vomiting During Early Pregnancy


Common Features*


Related to the pregnancy (obstetric)

Morning sickness

Mild nausea and vomiting that comes and goes and that occurs at varying times throughout the day, primarily during the 1st trimester

A doctor’s examination alone

Frequent, persistent nausea and vomiting

Inability to consume enough fluids, food, or both

Usually signs of dehydration, such as decreased urination, decreased sweating, a dry mouth, increased thirst, a racing heart, and dizziness when standing up

Weight loss

Blood tests to check for signs of dehydration and chemical imbalances by measuring levels of electrolytes, blood urea nitrogen (BUN), and creatinine

Urine tests to measure ketones (produced when not enough food is consumed and the body breaks down fats for energy)

Sometimes ultrasonography of the pelvis

A uterus that is larger than expected

No heartbeat or movement detected in the fetus during the 2nd trimester

Sometimes high blood pressure, swelling of the feet or hands, vaginal bleeding, or passage of tissue that resembles a bunch of grapes

Blood tests to measure human chorionic gonadotropin (hCG―a hormone produced by the placenta early in pregnancy)

Ultrasonography of the pelvis

A biopsy if no pregnancy is seen in the uterus

Not related to the pregnancy

Vomiting that began suddenly, usually accompanied by diarrhea

Sometimes recent contact with infected people or animals or recent consumption of undercooked, contaminated food or contaminated water

Sometimes a doctor’s examination alone

Sometimes examination and culture of stool

Symptoms that begin suddenly, usually in women who have had abdominal surgery in the past

Crampy pain and a swollen abdomen


Sometimes ultrasonography of the abdomen

Sometimes CT (if x-ray and ultrasound results are unclear)

An urge to urinate often (frequency), pain with urination (dysuria), a compelling need to urinate immediately (urgency), or difficulty starting to urinate (hesitancy)

With kidney infection, pain in the side or back and fever

Urine tests (urinalysis) and culture

* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

† Although a doctor's examination is always done, it is mentioned in this column only if the diagnosis can sometimes be made by the doctor's examination alone, without any testing.

CT = computed tomography.