It’s common to see contemporary TV shows portray women finding out about their pregnancies through sudden onset of nausea and vomiting.
Indeed, nausea and vomiting is a common condition in pregnancy. Even though it’s called “morning sickness”, it can occur any time during the day.
Nausea and vomiting of pregnancy usually starts before 9 weeks of pregnancy, i.e. first trimester. For most women, it goes away by 14 weeks of pregnancy. For some women, it lasts for several weeks or months. For a few women, it lasts throughout the pregnancy. Nausea and vomiting in pregnancy usually does not harm your health or your baby’s health. It also does not mean that your baby is sick. However, it may impact your daily activities.
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Why do pregnant women experience nausea and vomiting?
The exact underlying causes of nausea and vomiting in pregnancy is still poorly understood. However, scientists have a few working theories:
Hormonal changes
Pregnancy-related hormones, such as oestrogen and progesterone, relax smooth muscle and thus slow down the gastrointestinal transit time and may change gastric emptying. This can lead to nauseating feelings and vomiting. Another hormone called human chorionic gonadotropin (hCG), was detected at the highest level during the first trimester, the time when severe vomiting in pregnancy known as hyperemesis gravidarum is typically seen. Nonetheless, current scientific evidence showed results that are inconsistent with this theory, suggesting that no single hormone during pregnancy can accurately predict nausea and vomiting.
Abnormal gastrointestinal motility
Gastrointestinal motility refers to the contraction and relaxation of the smooth muscles that make up the digestive system. Some pregnant women experience abnormal gastrointestinal motility and relaxation of lower esophageal sphincter (a ‘gatekeeper’ that prevents food in the stomach from back flowing into the throat), leading to gastrointestinal reflux. As such, they’re more likely to feel nauseous during pregnancy.
Helicobacter pylori (H.pylori) infection
Y tambe, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons
H.pylori is a type of bacteria that typically infects and lives in the digestive tract, particularly the stomach. Most women with H. pylori do not develop severe nausea and vomiting of pregnancy, but the infection may play a role in developing nausea and vomiting in some women. In a systematic review and meta-analysis of epidemiological studies, it was found that pregnant women with H.pylori infection are more likely to develop the severe form of nausea and vomiting known as hyperemesis gravidarum.
Other reasons
Other reasons that may cause nausea and vomiting in pregnancy include:
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Nutrient deficiencies (eg, zinc, vitamin B6)
Treatment of nausea and vomiting in pregnancy
Most of the time, nausea and vomiting in pregnancy resolve on its own or with the help of lifestyle changes and medications.
Dietary changes
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Try eating before or as soon as you feel hungry to avoid an empty stomach.
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Eat snacks frequently and have multiple small meals (eg, six small meals a day) that are high in protein or carbohydrates and low in fat.
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Stick to a bland diet.
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Drink cold, clear, and carbonated or sour fluids (eg, 100 plus, lemonade) and drink these in small amounts between meals.
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Try smelling fresh lemon, mint, or orange or using an oil diffuser with these scents.
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Consuming ginger containing foods (eg, ginger lollipops, ginger ale) can be helpful in managing mild nausea and vomiting.
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Avoiding triggers
Anything that can trigger nausea and vomiting — odors, tastes, flickering lights, certain activities— should be avoided.
Medications
If lifestyle and dietary changes alone are not enough to manage nausea and vomiting, you may consult a healthcare professional for medical treatment.
In general, medications that are commonly prescribed for nausea and vomiting in pregnancy are:
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Vitamin B6 (pyridoxine) — Technically vitamin B6 is more of a supplement than a medication, but it can improve nausea and it’s safe with minimal side effects. The recommended dose of vitamin B6 is 10 to 25 mg orally every six to eight hours; the maximum treatment dose suggested for pregnant women is 200 mg/day.
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Antihistamines (e.g. dimenhydrinate, diphenhydramine, cyclizine, meclozine) — Antihistamines are also effective in improving nausea and vomiting in pregnancy. They are safe to be used during pregnancy and can be purchased from a pharmacy. Take note that antihistamines can cause drowsiness, hence they should not be taken prior to driving or operating machineries.
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Dopamine antagonist (e.g. metoclopramide, domperidone, promethazine, prochlorperazine) — These medications are usually reserved for more severe cases of nausea and vomiting and can only be purchased with a doctor’s prescription. They tend to have more side effects and can also cause drowsiness. There’s a lack of data about its safety in pregnancy, although they’re still considered safe to be used.
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Others, such as ondansetron and gastric medications.
Vomiting can also cause you to lose body fluids. Taking oral rehydration salts can help to replenish the fluids and electrolytes you’ve lost during vomiting. You can purchase them over-the-counter at any pharmacy.
When should you seek medical help
In rare cases, nausea and vomiting in pregnancy can be serious and even life-threatening. Hyperemesis gravidarum is the term for the most severe form of nausea and vomiting of pregnancy, which can lead to loss of weight and body fluids (dehydration). You should call your doctor if you have the following signs and symptoms of dehydration:
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You have a small amount of urine that is dark in color.
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You are unable to urinate.
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You cannot keep down 500ml of liquids per day.
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You are dizzy or faint when standing up.
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You have a racing or pounding heartbeat.
Sometimes, the nausea and vomiting may be caused by other causes besides pregnancy. Your doctor might suspect that you have one of these conditions if you have signs or symptoms that usually do not occur with nausea and vomiting of pregnancy. Some of these signs and symptoms include:
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Nausea and vomiting that occurs for the first time after 9 weeks of pregnancy
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Abdominal pain or tenderness
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Fever
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Headache
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Enlarged thyroid gland (swelling in the front of the neck)
It’s not easy to be pregnant, let alone be a parent. Thanks Mama!
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References
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ACOG Practice Bulletin No. 189: Nausea And Vomiting Of Pregnancy. Obstetrics & Gynecology. 2018;131(1):e15-e30.
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The Pharmaceutical Journal - Management of severe nausea and vomiting in pregnant women
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UpToDate - Nausea and vomiting of pregnancy: Clinical findings and evaluation
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UpToDate - Nausea and vomiting of pregnancy: Treatment and outcome
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