Nausea and vomiting are common in early pregnancy. What causes these symptoms and how are they treated?
Nausea and vomiting are common during the first trimester of pregnancy. About 75 percent of expectant mothers experience nausea and 50 percent experience vomiting. Although referred to as morning sickness, these symptoms can occur at any time of the day.
When does morning sickness begin and how long does it last?
Nausea and vomiting generally start between weeks 3 and 8 of pregnancy and last until the end of the first trimester. However, symptoms can persist up to the 20th week of pregnancy or, in rare cases, up to delivery.
Morning sickness doesn’t usually pose a risk to you or your baby. In some cases, however, it can decrease your quality of life. In addition, if you’re unable to keep food down, you may lack certain nutrients and become dehydrated. That’s why it’s important to treat these symptoms promptly.
What are the causes?
According to experts, morning sickness is likely caused by hormonal changes that occur early in the first trimester. Fatigue and emotional factors may also be involved.
Speak to your doctor if nausea and vomiting begin after 9 weeks, as this could be a sign of a health problem.
Morning sickness appears to be more common in certain cases:
If the mother is pregnant with twins or triplets
If she has experienced nausea or vomiting in a previous pregnancy
If her mother or sister experienced nausea or vomiting during pregnancy
If she suffers from motion sickness or migraines
If the baby is a girl
Can morning sickness be prevented?
It’s difficult to prevent morning sickness, but the following tips can help reduce the frequency and severity of symptoms.
- Avoid going too long without eating. Try to eat more often, but in smaller quantities.
- Eat light (e.g., toast or crackers) and wait 15 minutes before slowly getting out of bed in the morning.
- Eat foods you’re craving. For example, salty potato chips may help calm your stomach enough to allow you to eat.
- Avoid cooking or eating spicy, greasy, or fried foods.
- Open the windows or turn on the range hood to get rid of smells that make you nauseous.
- Get fresh air when you can and avoid getting too hot.
- Take naps or take a few days off work if necessary. Fatigue can aggravate nausea.
- If multivitamins increase your nausea, try taking them with food or just before bedtime. In addition, the Society of Obstetricians and Gynaecologists of Canada recommends that pregnant women suffering from nausea or vomiting stop taking their prenatal multivitamins if they contain iron, as iron can make nausea worse. These multivitamins can be safely replaced with a folic acid supplement or low-iron prenatal vitamins, as your iron needs don’t generally increase during the first trimester.
For some women, psychotherapy can help reduce their nausea, as it improves stress management and reduces anxiety.
How is morning sickness treated?
Some alternative treatments can help relieve nausea and vomiting.
It’s important to avoid becoming dehydrated. Make sure you drink small amounts of water frequently.
- Ginger is believed to have a calming effect on the stomach. Studies have shown that it’s effective in reducing nausea. It’s recommended to take a 250 mg ginger capsule four times a day. However, brands vary in effectiveness, so it’s best to ask a pharmacist for advice. Fresh ginger and grated ginger tea also relieve nausea, but the dosage is more difficult to control.
- Vitamin B6 supplements can also help reduce morning sickness.
- Acupuncture and acupressure are believed to have some effect against nausea and vomiting. You can even find special bracelets designed to apply pressure to a specific point on the wrist.
What if the vomiting is due to gastroenteritis?
To prevent dehydration, you can take a rehydration solution (e.g., Pedialyte®, Gastrolyte®). However, consult a doctor or pharmacist before taking anti-vomiting medications, such as dimenhydrinate (e.g., Gravol®), as they cause drowsiness.
Are there any anti-nausea medications?
However, some researchers have raised concerns about a potential link between Diclectin® and certain birth defects, including pyloric stenosis. According to the Centre IMAGe at CHU Sainte-Justine, even if there were a correlation, the risk to the fetus would be very small. The Society of Obstetricians and Gynaecologists of Canada (SOGC) maintains that Diclectin® is a safe medication for the treatment of morning sickness.
To determine whether you need medication for your nausea and vomiting, it’s important to assess the extent to which they affect your daily life. Treating nausea and vomiting quickly can prevent several complications, including hospitalization, and help you resume your normal activities.
The most common anti-nausea medication is Diclectin®, a combination of an antihistamine and vitamin B6. According to Health Canada, this medication is effective in relieving nausea. However, relief of symptoms is not instantaneous, as it takes 4 to 6 hours to start working.
Health Canada also states that Diclectin® is safe for the baby. Studies have determined that taking it during pregnancy does not harm the unborn child.
Diclectin® is available after consulting with a pharmacist or doctor. Your pharmacist can prescribe medication for pregnancy-related nausea and vomiting. However, a consultation is necessary to assess whether you meet the criteria for a prescription. Your midwife or your specialized nurse practitioner (SNP) can also prescribe this medication.
Treating extreme morning sickness
Some expectant mothers experience nausea and vomiting so severe that it jeopardizes their health and that of their baby. Known as hyperemesis gravidarum, this condition is believed to affect 1 to 3 percent of pregnant women.
Be sure to speak to your doctor if you experience the following:
Nausea or vomiting that interferes with your daily activities
Signs of dehydration, such as dry mucous membranes (mouth, nose) and dark urine
Severe and persistent vomiting
Hyperemesis gravidarum requires treatment to stop the vomiting. Women suffering from this condition need to stay hydrated and keep up their nutrition. Hospitalization may be necessary in certain cases.
Things to keep in mind
Most women experience nausea or vomiting during pregnancy.
Nausea and vomiting during pregnancy is generally not harmful to either the mother or her baby.
Your pharmacist or doctor can prescribe the main treatments for nausea during pregnancy.
If nausea and vomiting are disrupting your daily activities, if you lose weight, or if you develop symptoms of dehydration, consult your doctor.
Scientific review: Alexandre Chagnon, pharmacist
Research and copywriting: The Naître et grandir team
Updated: June 2021
Please note that hyperlinks to other websites are not updated regularly, and some may have changed since publication. If a link is no longer valid, use search engines to find the relevant information.
Beaulieu, Marie Josée. Durant la grossesse, nausées et vomissements. www.oiiq.org
Borrelli, Francesca, et al. Obstetrics & Gynecology, vol. 105, no. 4, 2005, pp. 849–856.
Campbell, K, et autres. The Management of Nausea and Vomiting of Pregnancy. SOGC clinical practice guideline, volume 38, issue 12, p1127-1137, 2016.18
CHUM Birthing Centre. “Malaises courants.” www.chumontreal.qc.ca
Doré, Nicole, and Danielle Le Hénaff. From Tiny Tot to Toddler: A practical guide for parents from pregnancy to age two. Quebec City, Institut national de santé publique du Québec. www.inspq.qc.ca
Frellick, Marcia, and Laurie Barclay. “ACOG Issues Guideline on Nausea/Vomiting in Pregnancy.” Medscape, 2015. www.medscape.org
Ladewig, Patricia, et al. Soins infirmiers en périnatalité. 4th ed., Quebec City, Éditions du Renouveau pédagogique, 2010.
Jin, Jill. "Treatments for Nausea and Vomiting During Pregnancy", JAMA, vol. 316, n° 13, 2016, p.1420. jamanetwork.com
Malo, Josianne. Summary of the article “Should doxylamine-pyridoxine be used for nausea and vomiting of pregnancy?” 2014. www.chusj.org
Persaud, Navindra, et al. “Should doxylamine-pyridoxine be used for nausea and vomiting of pregnancy?” Journal of Obstetrics and Gynaecology Canada, vol. 36, no. 4, 2014, pp. 343–348.
The Society of Obstetricians and Gynaecologists of Canada. “Nausées et vomissements de la grossesse.” sogc.org
The American College of Obstetricians and Gynecologists. “Morning Sickness: Nausea and Vomiting of Pregnancy.” FAQ no. 126, 2020. www.acog.org