Nausea and vomiting of pregnancy (NVP), which usually starts between 5 and 12 weeks of pregnancy, is quite common; up to 80% of pregnant women experience nausea and vomiting at some point in their pregnancies and between 3-6% of pregnant women experience severe nausea and vomiting, which we commonly refer to as hyperemesis gravidarum. The symptoms usually peak around 9 weeks and typically improve by weeks 16 to 18 of pregnancy. Unfortunately for some women these symptoms actually persist through pregnancy (up to 20% of women have symptoms until the third trimester and for 5% of women their symptoms persist until delivery) But just because it’s common doesn’t mean it’s something that women just have to deal with, in fact, it’s quite the opposite.
Nausea and vomiting in pregnancy can significantly impact your quality of life, your mental health; it can increase anxiety and worry about how it’s affecting the fetus, how it’s affecting your ability to work and can also impact your relationships.
Why do women get nausea and vomiting in pregnancy?
Believe it or not...the cause of nausea and vomiting in pregnancy is not entirely understood! Hormonal changes are thought to play a significant role, including elevated levels of estrogen, though the rising levels of bHCG, human chorionic gonadotropin, which peaks in the first trimester is thought to significantly contribute to the symptoms as well.
Additional theories include abnormal gastric motility, meaning your stomach may empty more slowly than usual. What’s really interesting is that it’s not just the hormonal or gastric changes that occur, but how your body responds to these changes that makes some women more likely to experience nausea and vomiting. Genetics (including family history or personal history) is often thought to play a role, so if your siblings or mother had NVP, there is a good chance you may experience it as well.
Why do we want you to tell us about it?
We want to help. Even if your symptoms are mild, we’ve got many tips and tricks (that we’ll get to soon) to help you manage your symptoms.
Also, because nausea and vomiting of pregnancy ‘aka morning sickness’, is what we call a diagnosis of exclusion. What this means is that we, as your care providers, need to make sure that there is nothing else going on causing your symptoms. Just because you’re pregnant, doesn’t mean that we are going to simply brush off symptoms.
We need to review your symptoms and ensure that we’re not concerned there could be something else at play contributing to how you are feeling, like thyroid abnormalities, side effects of another medication or substance use (marijuana can sometimes be thought of as a treatment for nausea and vomiting, and we’ll talk more about cannabis use in another episode, but chronic use can actually be an underlying cause for nausea and vomiting).
Additional things we need to exclude include infection, underlying eating disorder (like anorexia or bulemia) and several other less common causes like migraines and other more rare hormonal causes.
How do we diagnose it?
Typically it’s diagnosed by process of elimination. It must onset in the first trimester and we must exclude other possible causes of your symptoms (as described above). If your symptoms start after the first trimester, then we’d be more suspicious that something else may be going on causing you to have nausea and vomiting.
Why do we want to initiate treatment early?
The reason we want to initiate treatment early is to help YOU get your symptoms under control as early as possible. If we start treating early, it is possible that we may prevent more serious complications like dehydration, weight loss, and the need for hospitalization.
Additionally, if we delay treatment until your symptoms are severe and you’re experiencing complications it can become more difficult to get those symptoms under control.
What treatment options do we have?
We break treatment options down into two categories non-pharmacological (i.e not medication) and pharmacological (medications).
Please DO NOT use marijuana, THC or CBD products. They have NOT been shown to be safe in pregnancy and are NOT recommended for treatment. Additionally, long-term marijuana use and withdrawal can actually increase nausea and vomiting.
If the above mentioned strategies aren’t cutting it, which is the case for many women in early pregnancy, we often turn to medications that can reduce symptoms and improve quality of life.
Vitamin B6 - Vit B6, also referred to as pyroxidine, is a water soluble vitamin and has an excellent safety profile and given that it’s a vitamin many women are comfortable starting here. As a single agent, the recommended dose of pyridoxine is 10 to 25 mg orally every six to eight hours; the maximum treatment dose suggested for pregnant women is 200 mg/day. Studies have shown that it can be effective at improving mild to moderate nausea, but doesn’t really reduce vomiting.
Our next go to, if Vit B6 alone isn’t effective at controlling nausea, is the combination of Doxylamine succinate and pyridoxine (in Canada this is a well known product referred to by it’s trade name Diclectin; Diclegis and Bonjesta in the United States). Doxylamine is a first generation antihistamine, and pyridoxine, as we just learned, is Vitamin B6.
Doxylamine-pyridoxine as a combination treatment appears to be more effective than either drug alone and it’s safety has been well established in pregnancy.
Initially, we prescribe two extended-release tablets (each tablet contains doxylamine 10 mg and pyridoxine 10 mg) at bedtime. The dose may be increased to four tablets over the course of the day, as needed, for more severe nausea (one tablet in the morning, one tablet in the midafternoon, two tablets at bedtime). Important to note that this medication is more for prevention than for treatment. So if your nausea is worse in the morning, take it before bed. If worse in the afternoon, take in the morning...you get the gist!
If lifestyle and dietary changes in combination with doxylamine/pyriodoxine is ineffective at managing your nausea then we typically look at medications targeted to more severe symptoms.
The next step after Diclectin is often dimenhydrinate (commonly referred to in Canada by it’s trade name Gravol). It can be taken orally and also rectally every 4-6 hours. We also often give this intravenously in hospital for women who are admitted with severe NVP (hyperemesis).
If dimenhydrinate isn’t able to get your NVP under control the next medication we often turn to is metoclopramide (Maxeran). These are dopamine antagonists that aid in stimulating gastric motility and emptying your stomach. This can be taken by mouth, or additionally can be given through an intravenous or intramuscular (shot in the leg/arm) up to 3-4 times/day. We have excellent data available that reassures us that this is safe in pregnancy.
If you’ve tried a combination of at least two of the above medications with little to no improvement in your NPV, we often then turn to ondansetron (zofran).
You may have heard some controversy in this medication in pregnancy due to the possible small increase risk in cleft palate and cardiac anomalies in babies born to mothers who used this drug in the first trimester of pregnancy. Currently it’s listed as a pregnancy category B medication, which means there is no evidence of risk in studies, but this has not been confirmed in controlled studies in women in the first trimester.
In addition to the above, we will often recommend trialing acid-reducing medications as these combined with anti-nausea medications can often offer a significant improvement in symptoms. Medications commonly used include ranitidine, or esomeprazole.
If you are experiencing severe NVP, which we refer to as hyperemesis, you will likely need to be admitted to hospital for initiation of your management. Hyperemesis typically presents with women who have persistent vomiting associated with weight loss, low blood pressure and often laboratory abnormalities (electrolytes).
Women are often most concerned not with their symptoms but how the NVP is affecting the fetus. Fear not, there is no increase in fetal malformations of infants born to mothers with NVP or hyperemesis, regardless of what medications they did or didn’t take. There is often no difference in birth weight or gestational age at time of birth for women who were affected by NVP/hyperemesis compared to those that weren’t as long as they had a normal pre-pregnancy weight and they had appropriate weight gain later in pregnancy.
So, you’re pregnant now and you’re wondering when you should seek help? Generally we’d recommend seeking help in the following situations:
Another question is, is this likely to happen in subsequent pregnancies, and unfortunately the answer is yes. So is there anything you can do to prevent it next time around?
Well making sure you’re taking a prenatal vitamin with folic acid at least 1 month prior to conception can reduce the risk of fetal malformation and may decrease the frequency and severity of NVP. B-complex vitamins taken pre-conception and early pregnancy may also reduce NVP. Additionally if you have heartburn or acid reflux pre=pregnancy getting these symptoms under control before you get pregnant may reduce the severity of symptoms while pregnant. And if we know you’re at high risk, consider starting doxylamine/pyridoxine at the onset of pregnancy to try to prevent your symptoms from snowballing out of control!
Take home points: