What Causes Morning Sickness?

Medically reviewed by George Krucik, MD, MBA

Morning sickness is a common symptom of pregnancy and is marked by nausea and occasional vomiting. Despite the name, morning sickness can cause discomfort at any time of the day. Morning sickness usually happens within the first four months of... Read More

Morning sickness is a common symptom of pregnancy and is marked by nausea and occasional vomiting. Despite the name, morning sickness can cause discomfort at any time of the day.

Morning sickness usually happens within the first four months of pregnancy and is often the first sign that a woman is pregnant.

There are various ways to alleviate morning sickness, and complications are rare.

Causes of morning sickness

There is no one cause of morning sickness during pregnancy, and severity varies among women. Increased hormone levels during the first few weeks of pregnancy is among the most common causes. Reduced blood sugar is another common cause of morning sickness.

Other factors can exacerbate morning sickness. These include:

  • having twins or triplets
  • excessive fatigue
  • emotional stress
  • frequent traveling

Morning sickness can vary between pregnancies. While you may have had severe morning sickness during one pregnancy, in future pregnancies it may be very mild.

Risks of morning sickness

Nausea and vomiting can easily cause a loss of appetite. Many pregnant women worry that this will harm their babies. Mild morning sickness is generally not harmful.

Women who experience morning sickness well beyond the first three to four months of their pregnancies should speak with their doctors. Also seek help if you aren’t gaining any weight during pregnancy.

Possible complications of morning sickness

Morning sickness is usually not severe enough to hinder fetal growth and development. Some pregnant women experience severe vomiting and weight loss because of the nausea. This is called hyperemesis gravidarum. This condition causes electrolyte imbalances and unintentional weight loss. If left untreated, this condition may eventually harm your baby.

Call your doctor immediately if you experience:

  • an inability to keep food down
  • weight loss of 2 pounds or more
  • fever
  • infrequent urination with small quantities of dark colored urine
  • lightheadedness or dizziness
  • fast heartbeat
  • severe nausea within the second trimester
  • blood in your vomit
  • frequent headaches
  • abdominal pain
  • spotting, or bleeding

Severe bouts of morning sickness generally require hospitalization. Hyperemesis gravidarum often requires intravenous (IV) fluids for rehydration.

Treatment for morning sickness

Your doctor may prescribe supplements or medications to alleviate nausea and to help you retain foods and fluids. Medications your doctor may prescribe include:

  • antihistamines: to help with nausea and motion sickness
  • phenothiazine: to help calm severe nausea and vomiting
  • metoclopramide (Reglan): to help the stomach move food into the intestines and help with nausea and vomiting
  • antacids: to absorb stomach acid and help prevent acid reflux

Do not take these medications on your own without first talking with your doctor.

Some people find that alternative remedies may also help relieve morning sickness. Make sure you only try these after first discussing them with your doctor. These remedies include:

  • vitamin B-6 supplements
  • prenatal vitamins
  • ginger products, including ginger ale, ginger tea, and ginger drops
  • saltine crackers
  • acupuncture
  • hypnosis

Tests for morning sickness

Based on your symptoms, your doctor may order some tests to make sure that you and your baby are safe. These include:

Urine tests

Urine tests can determine whether you are dehydrated.

Blood chemistry tests

Your doctor may order blood chemistry tests that include:

  • complete blood count (CBC)
  • comprehensive metabolic panel
  • comprehensive metabolic panel (Chem-20), to measure the electrolytes in your blood.

These tests will determine whether you are:

  • dehydrated
  • malnourished, or deficient in certain vitamins
  • anemic


Ultrasound uses sound waves to produce images of your baby. The doctor then uses these images and sounds to check that your baby is developing at a healthy rate.

Preventing morning sickness

Taking the following steps may help prevent or minimize nausea:

  • Drink plenty of water.
  • Drink water before and after meals.
  • Take naps.
  • Ventilate your home and workspace to eliminate scents that make you nauseous.
  • Avoid spicy foods.
  • Eat small meals.
  • Avoid fatty foods.
  • Take vitamins at night.
  • Avoid cigarette smoke.

If none of these preventative measures works, or if you experience morning sickness beyond the first three to four months of your pregnancy, it’s important you speak with your doctor. Also, make sure you only try medications and alternative remedies after first discussing these options with your doctor.

Medically reviewed by Rachel Liberto, RN on December 15, 2016Written by Kristeen Moore

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This feature is for informational purposes only and should not be used to diagnose. Please consult a healthcare professional if you have health concerns.

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