Morning Sickness (Toxicosis) During Pregnancy

🔬 What Is Morning Sickness (Toxicosis) During Pregnancy?

Toxicosis (from Greek toxikon — poison) refers to a set of pathological conditions that arise exclusively in connection with pregnancy. It is important to understand that toxicosis is not just nausea. It is a syndrome that may include:

• Nausea — ranging from mild to unbearable, most commonly in the morning but can persist throughout the day
• Vomiting — from isolated episodes to multiple occurrences per day
• Ptyalism (excessive salivation) — sometimes up to 1-1.5 liters per day
• Changes in taste preferences — aversion to certain foods, cravings for unusual items
• Heightened sense of smell — intolerance to odors that previously caused no discomfort
• Decreased appetite — up to complete refusal to eat
• General weakness — drowsiness, irritability, decreased work capacity

In the international classification (ICD-11), Nausea and Vomiting of Pregnancy (NVP) is recognized as a separate condition. It is not a disease but a physiological response to pregnancy. However, in 0.3-3% of women, NVP progresses to Hyperemesis Gravidarum (HG) — a severe condition requiring medical intervention.

Studies show that nausea and vomiting of varying severity affect 50% to 90% of pregnant women. It is the most common "side effect" of pregnancy, especially in the first trimester.

📊 3 Severity Grades of Morning Sickness

Classifying morning sickness by severity helps clinicians choose the appropriate treatment strategy. Key criteria include frequency of vomiting, weight loss, and the woman's overall condition.

Important: If you are losing weight, cannot keep fluids down for 12 hours, or notice dark urine, seek medical attention immediately. Dehydration is dangerous for both mother and fetus.

Hyperemesis gravidarum (HG) is not simply "severe morning sickness" — it is a distinct pathological condition. It occurs in 0.3-3% of pregnancies and can lead to serious complications: Wernicke encephalopathy (vitamin B1 deficiency), kidney and liver damage, and thromboembolism due to dehydration.

🧬 Causes of Morning Sickness

The exact cause of morning sickness remains unknown. Modern medicine considers it a multifactorial condition in which several mechanisms interact simultaneously:

Hormonal Factor (Primary)

Human chorionic gonadotropin (hCG) is the primary suspect. hCG levels rise sharply during the first trimester, and the peak of morning sickness coincides with peak hCG (weeks 8-12). In multiple pregnancies and hydatidiform mole (when hCG is particularly high), morning sickness is more severe. hCG stimulates thyroid receptors, causing transient thyrotoxicosis that exacerbates nausea.

Estrogen increases the sensitivity of olfactory receptors and affects gastrointestinal motility. High estradiol levels correlate with morning sickness severity.

Progesterone relaxes smooth muscles, including those of the esophagus and stomach, slowing peristalsis and promoting reflux and nausea.

Other Factors

• GDF15 (Growth Differentiation Factor 15) — research from 2023-2024 (Nature, Marlena Fejzo et al.) demonstrated that this placental hormone is a key mediator of nausea. Women with genetically lower pre-pregnancy GDF15 levels tolerate its sharp increase less well
• Helicobacter pylori — meta-analyses (Gastroenterology Clinics, 2011) show an association between H. pylori infection and severe morning sickness. H. pylori is found significantly more often in women with HG
• Genetic predisposition — if the mother had severe morning sickness, her daughter's risk increases threefold. Concordance is higher in monozygotic twins than in dizygotic twins
• Psychosomatic factor — stress, anxiety, and unplanned pregnancy can worsen symptoms. However, this does not mean morning sickness is "all in the head" — it has a clear biochemical basis
• Evolutionary theory — the "protective" hypothesis suggests that morning sickness shields the embryo from potentially toxic substances during the critical period of organogenesis (weeks 5-12)

📅 Timeline: When It Starts and When It Ends

Morning sickness follows a characteristic timeline linked to gestational age and hormone levels:

Early toxicosis (first trimester) is the condition discussed in this article. It is related to the body's adaptation to pregnancy and is relatively safe (except in severe cases).

Late "toxicosis" (preeclampsia, gestosis) is an entirely different condition that occurs after week 20. It is characterized by elevated blood pressure, edema, and proteinuria. It is not a continuation of early morning sickness but a separate pathology with different causes and mechanisms. Preeclampsia requires careful monitoring and can be dangerous.

If nausea and vomiting first appear after weeks 10-12 or return after having resolved, this warrants investigation, as the cause may not be morning sickness (gastrointestinal disease, infection, thyroid pathology, etc.).

💊 Treatment of Morning Sickness

The treatment approach depends on severity. Non-pharmacological methods are always tried first.

Non-Pharmacological Treatment (First Line)

• Diet: Eat small portions every 2-3 hours. Avoid fatty, spicy, and strongly scented foods. In the morning, eat a cracker or dry toast before getting out of bed. Cold food is better tolerated — less odor
• Fluids: Drink between meals, not during. Small sips. Good options include water with lemon, ginger tea, and peppermint tea (if tolerated)
• Ginger: Proven efficacy (Cochrane Review, 2015). 250 mg of dried ginger 4 times a day or fresh ginger tea. Safe at recommended doses (up to 1 g/day)
• Vitamin B6 (pyridoxine): Recommended by ACOG as first-line therapy. Dose: 10-25 mg 3-4 times a day. Reduces nausea but has less effect on vomiting
• Acupressure: P6 point (Nei-Guan) on the wrist. Some studies show moderate efficacy. Sea-sickness wristbands work on this principle
• Lifestyle: Get enough sleep (8-9 hours), avoid sudden movements in the morning, ventilate rooms, and avoid trigger odors

Pharmacological Treatment (By Prescription Only)

Warning: No medication should be taken on your own during pregnancy! A doctor may prescribe:

• Doxylamine + pyridoxine — a combination recommended by ACOG and SOGC as first-line pharmacotherapy (Diclegis/Diclectin). Safety confirmed in studies involving over 200,000 pregnant women
• Antihistamines — dimenhydrinate, promethazine (by prescription)
• Ondansetron (Zofran) — when other treatments are ineffective. Safety data are conflicting; prescribed only when benefits outweigh risks
• Metoclopramide — short courses for moderate to severe cases

Treatment of Severe Morning Sickness (Hyperemesis)

Severe cases require hospitalization:

• Intravenous fluid therapy — IV solutions to correct dehydration and electrolyte imbalances
• Thiamine (Vitamin B1) — mandatory before glucose administration to prevent Wernicke encephalopathy
• Parenteral nutrition — in extreme cases when oral intake is impossible
• Corticosteroids — as a last resort for refractory hyperemesis

When hospitalization is needed: Inability to keep fluids down for 12+ hours, signs of dehydration (dark urine, dry mucous membranes, dizziness upon standing), weight loss exceeding 5% of initial weight, ketones in urine, tachycardia above 100 bpm.

🛡️ Prevention of Morning Sickness

Completely preventing morning sickness is not possible, but you can reduce the risk of a severe course:

Before Pregnancy

• Multivitamins with folic acid: Research (Czeizel AE, Am J Obstet Gynecol, 2004) showed that taking multivitamins before conception reduces the risk of severe morning sickness. Start taking folic acid (400-800 mcg/day) at least 1 month before the planned pregnancy
• Treat H. pylori: If you have chronic gastritis, get tested and treated before pregnancy
• Normalize weight: Both overweight and underweight increase the risk of severe morning sickness
• Psychological preparation: A planned, desired pregnancy with partner support is associated with a milder course

In Early Pregnancy

• Sleep schedule: Go to bed by 10-11 PM and sleep at least 8 hours. Sleep deprivation worsens nausea
• Avoid triggers: Identify which smells, foods, or situations provoke nausea and minimize exposure
• Keep snacks handy: Crackers, dry toast, nuts by the bedside — eat before getting up
• Do not skip meals: An empty stomach worsens nausea. Eat small portions every 2-3 hours
• Ventilate rooms: Fresh air reduces nausea from household odors
• Wear comfortable clothing: Tight clothing that presses on the abdomen can worsen symptoms

Remember: Morning sickness is temporary. In the vast majority of women, it resolves by the end of the first trimester and has no impact on the baby's health. Research even shows that moderate morning sickness is associated with a reduced risk of miscarriage (Hinkle SN et al., JAMA Internal Medicine, 2016). However, if symptoms significantly impair your quality of life or are worsening, be sure to consult your doctor.