Nausea and Vomiting of Pregnancy, Including Hyperemesis Gravidarum

By
Shannon M. Clark, MD
|
July 22, 2022
Nausea and Vomiting of Pregnancy, Including Hyperemesis Gravidarum

You're pregnant! Congrats!

There is often great excitement when being newly pregnant. However, a common and very unpleasant side effect of pregnancy is nausea and vomiting. Depending on how severe the symptoms are, it can significantly affect a pregnant person’s quality of life making it difficult to work, care for other children or family members, or even do day-to-day activities.The good news is that nausea and vomiting of pregnancy (NVP) is most commonly present between 8 weeks to 14 weeks of gestation, but for some pregnant persons, it can last for several months. The most severe form of NVP is called hyperemesis gravidarum (HG). It occurs in 0.3-3.0% of pregnancies, with a recurrence rate of 15-18% in subsequent pregnancies. HG is something that is definitely not talked about enough!

What differentiates HG from NVP, and how is it diagnosed?

HG is the term used to describe the severe end of the symptom spectrum of NVP (including weight loss exceeding 5% of pre-pregnancy body weight). The most common criteria used for diagnosis include:

  • Persistent vomiting unrelated to other causes
  • Significant, large ketonuria
  • Electrolyte, liver and thyroid function tests may be abnormal
  • 5% weight loss from pre-pregnancy weight

Thankfully, there are both nonpharmacologic (conservative) and pharmacologic measures and treatment options available to help manage the symptoms of NVP and HG.

Conservative measures:

Nonpharmacologic Dietary Measures⬇️

  • Avoid a full stomach with frequent, small meals every 1–2 hours
  • Minimize spicy or fatty foods
  • Eliminate supplemental iron
  • Substitute folic acid for iron-containing prenatal vitamins
  • Eat Bland or dry foods
  • Consume high-protein snacks and crackers in the morning before getting out of bed
  • Take ginger 250 mg 4 times per day

Nonpharmacologic Lifestyle measures⬇️

  • Avoid sensory stimuli

                  *Odors, heat, humidity, noise, and flickering lights/stimuli that may provoke onset of symptoms

  • If possible, begin taking prenatal vitamins for 1 month prior to conception (may reduce symptoms).
  • Try acupressure, acupuncture, or electrical nerve stimulation (acustimulation)

                   *P6 or Neiguan point (located three finger breadths below the wrist on the inside of the wrist in between the two tendons)

                   *Evidence is inconclusive with conflicting conclusions

                   *Consider P6 acupressure with wrist bands

Pharmacologic measures:

Pharmacologic treatment will require a prescription from your physician.

Medications⬇️

  • Vitamin B6 (pyridoxine) or Vitamin B6 plus doxylamine (Unisom)
  • Vitamin B6

                    *10-25 mg orally (alone or in combination with doxylamine 12.5 mg orally) 3 or 4 times per day OR

  • Vitamin B6 10 mg/ doxylamine 10 mg combination (Diclegis)

                     *2 tablets orally at bedtime initially, up to 4 tablets per day (1 tablet in the AM, 1 tab in the midafternoon, and 2 tablets at bedtime)

If Symptoms Persist Add the Following:

  • Dimenhydrinate

                    *25-50 mg every 4 to 6 hours, orally as needed (do not exceed 200 mg per day if also on doxylamine) OR

  • Diphenhydramine

                    *25-50 mg every 4 to 6 hours, orally OR

  • Prochlorperazine

                    *25 mg every 12 hours, rectally OR

  • Promethazine

                    *12.5-25 mg every 4 to 6 hours, orally or rectally

If Symptoms Persist but No Dehydration Add Any of the Following:

  • Metoclopramide

                    *5-10 mg every 6 to 8 hours, IM or orally

  • Ondansetron

                    *4 mg orally every 8 hours

  • Promethazine

                    *12.5-25 mg every 4 to 6 hours, orally, IM or rectally

  • Trimethobenzamide

                   *200 mg every 6 to 8 hours, IM

If Symptoms Persist and the Patient is Dehydrated:

  • IV fluid replacement

                    *If patient vomiting for > 3 weeks

                    *Add IV thiamine followed by IV multivitamins are recommended to prevent Wernicke encephalopathy

If Symptoms Persist Even With the Addition of IV Fluids, Add Any of the Following:

  • Dimenhydrinate IV

                    *50 mg (in 50 mL saline, over 20 min) every 4 to 6 hours

  • Metoclopramide IV

                    *5-10 mg every 8 hours

  • Ondansetron IV

                   *8 mg, over 15 minutes, every 12 hours

  • Promethazine IV

                    *12.5-25 mg every 4 to 6 hours

If Symptoms Still Persist Despite IV Fluids and Above IV Medications, Add the Following:

  • Chlorpromazine

                    *25-50 mg every 4 to 6 hours IM or IV or 10-25 mg orally every 4 to 6 hours

  • Methylprednisolone

                    *16 mg every 8 hours orally or IV for 3 days

                    *Taper over 2 weeks to lowest effective dose

                    *Limit duration to 6 weeks

Initiating early treatment

As ACOG states, risk of HG increases with, “being pregnant with more than one fetus, a previous pregnancy with either mild or severe nausea and vomiting, your mother or sister had severe nausea and vomiting of pregnancy, a history of motion sickness or migraines, or being pregnant with a female fetus.” If you have experienced severe NVP  in a previous pregnancy or have a combination of the above mentioned risk factors, you might want to discuss this with your OBGYN as soon as you find out you're pregnant to initiate medications prior to the onset of symptoms.

Once symptoms are managed with medications, you will stay on 1 or 2 medications scheduled daily, with another medication available for break-thru symptoms. Once a successful treatment regimen is established, you would stay on that regimen until out of the first trimester, then slowly taper off medications as tolerated.

Keep in mind, a patient’s perception of the severity of symptoms and one’s desire for treatment are influential in clinical decision making. There are safe and effective medications available if needed, and patients should not be expected to just “deal with it”.

Additional general principles of management may include:

  • IV hydration should be used for patients who cannot tolerate oral liquids or if clinical signs of dehydration are present
  • Ketosis and vitamin deficiency should be corrected
  • Rule out other causes of intractable vomiting before making a diagnosis of hyperemesis gravidarum
  • If nausea and vomiting persist after 20 weeks, test for H. pylori
  • Referral to a nutritionist is ideal
  • Be mindful of potential side effects and interactions of multiple medications as many patients will need more than one medication
  • Consider referral to therapist as severe symptoms can precipitate symptoms of anxiety and depression

What are the effects of HG on a fetus?

Evidence is conflicting as to whether or not there is a higher incidence of small for gestational age and premature infants born to those with HG. You can rest easier, though, knowing that there is NO association noted with perinatal or neonatal mortality, and mild to moderate vomiting has little effect on pregnancy outcome. In fact, lower rates of miscarriage have been documented, likely due to healthy placenta and the protective effect of NVP. The important thing is to discuss it with your OBGYN if symptoms develop or if you are concerned that you’re at risk for developing the symptoms so treatment can be started if necessary.

Resources:

Morning Sickness: Nausea and Vomiting of Pregnancy

ACOG Guidelines at a Glance: Nausea and Vomiting of Pregnancy

ACOG Practice Bulletin No. 189: Nausea And Vomiting Of Pregnancy

Nausea and vomiting of pregnancy: Treatment and outcome

Shannon M. Clark, MD

Shannon M. Clark, MD

Shannon M. Clark, MD, MMS is a double board certified ObGyn and Maternal-Fetal Medicine Specialist, and founder of Babies After 35. In her roles as a clinician, educator and researcher at UTMB-Galveston, she focuses on the care of people with maternal and/or fetal complications of pregnancy. Dr. Clark has taken a special interest in pregnancy after the age of 35, which according to age alone, is considered a high-risk pregnancy.

Follow Shannon on TikTok @tiktokbabydoc, Facebook @babiesafter35, and Instagram @babiesafter35.

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