Nausea and vomiting during pregnancy

The vast majority of women — up to 85% — experience nausea and vomiting of pregnancy (NVP) to varying degrees. 

In general, nausea begins between the 4th and 6th weeks of pregnancy and peaks between weeks 11 and 13.  In approximately 50% of cases, nausea subsides around week 14. However, it may continue for several more weeks or even months. Some women suffer throughout their pregnancy.  


Scientists do not know the exact cause of nausea and vomiting of pregnancy, but it seems to result from multiple factors. The most common theory is that hormonal changes, such as the increase in human chorionic gonadotropin (hCG), estrogen and progesterone, directly contribute to nausea during the first trimester. Gastric dysrhythmia and Helicobacter pylori (H. pylori) infections have also been associated with NVP. Women who suffer from thyroid problems or gastrointestinal disorders seem to be more susceptible to experiencing more severe NVP symptoms.

In general, NVP does not pose a hazard to the health of the mother or her fetus, but it is important to manage symptoms in order to ensure that the mother consumes sufficient fluids and nutrients and minimize the impact on her quality of life.

Managing NVP

Since women’s first appointment with a healthcare provider usually occurs around the 12th week of pregnancy, if not later, how should expectant mothers deal with their NVP symptoms?

It is important to talk to a healthcare provider as soon as possible because early intervention will help prevent nausea and vomiting from increasing in severity. Women with mild to moderate NVP can try to control their symptoms by changing some lifestyle habits and eliminating certain foods that aggravate their symptoms. However, those with moderate to severe NVP symptoms might require treatment with a medication specially designed to ease their symptoms. Regardless of the severity of symptoms, all pregnant women should be informed of the options that are available.

In addition to making an appointment with a healthcare provider, pregnant women can also call the Motherisk NVP Disease Management Helpline. This bilingual service provides evidence-based information on the condition and strategies to effectively manage symptoms.

When NVP symptoms are severe

When morning sickness lasts throughout the day and even into the night, many women lose weight and cannot retain the nutrients that are essential to a healthy pregnancy and to the development of their fetus.

Hyperemesis gravidarum (HG) is the most severe form of NVP, affecting between 0.3% and 3% of pregnant women. HG is defined as a loss of 5% of the mother’s pre-pregnancy weight, often associated with a state of malnutrition, uncontrollable vomiting and dehydration. It is a very serious condition that must be discussed with a healthcare professional.  

Did you know that women who have suffered from severe NVP or HG in a previous pregnancy have a 75%-85% chance of experiencing the same symptoms in a subsequent pregnancy? It may be helpful to speak to a healthcare provider about screening for Helicobacter pylori (H. pylori) infection, as it has been associated with severe NVP and HG.

Regardless of the severity of symptoms, here are a few useful tips to reduce their severity and frequency:

  • Eat small meals every 1-2 hours. Avoid getting hungry or thirsty.
  • Include a source of protein (e.g. nuts, cheese, Greek yogurt, etc.) in every snack and meal to help maintain sugar levels.
  • Drink cold liquids (ice cubes, popsicles, slushes, smoothies).
  • Allow 30 minutes between consuming liquids and solids at mealtime.
  • Rest as much as possible.

Most women who follow these tips see a reduction in their symptoms. Non-pharmaceutical methods, such as acupuncture, ginger and vitamin B6 supplements, may also help some women.

Impact of NVP on pregnancy

Studies suggest that women who suffer from NVP experience fewer miscarriages and premature births. However, in cases where severe NVP symptoms have not been well controlled, studies show that NVP/HG to can lead to low birth weight or preterm delivery.

Pharmaceutical treatment

In certain cases of NVP, pharmaceutical treatment may be recommended. If more conservative measures do not adequately control your symptoms, speak to your healthcare provider. He or she may prescribe a safe and effective medication indicated for treating this condition.


Several sources of information regarding NVP are available:

We would like to thank Caroline Maltepe, BA, Coordinator, Motherisk Nausea and Vomiting of Pregnancy Helpline who provided valuable information for this article sponsored by Duchesnay.

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