When does morning sickness typically start during pregnancy?

When Does Morning Sickness Start in Pregnancy?

Morning sickness typically begins at 4-6 weeks of pregnancy, peaks at 8-12 weeks, and usually subsides by week 20 for most women. 1

Timeline and Patterns

Morning sickness follows a predictable pattern:

• Initial onset: 4-6 weeks of pregnancy
• Peak intensity: 8-12 weeks of pregnancy
• Resolution: By week 14 for approximately 80% of women 1, 2
• Complete resolution: Usually by week 20 for most women 1

Despite being called "morning sickness," symptoms can occur at any time of day or night 2.

Prevalence and Severity

• Affects approximately 70-80% of pregnant women 3, 4
• Exists on a spectrum of severity:
  • Mild to moderate nausea and vomiting of pregnancy (NVP) is most common
  • Hyperemesis gravidarum (HG), the severe form, affects 0.3-3% of pregnant women 1, 2

Pathophysiology

Morning sickness is associated with several physiological changes during pregnancy:

• Elevated levels of human chorionic gonadotropin (hCG)
• Increased estrogen levels
• Changes in gastrointestinal motility
• Progesterone effects that inhibit GI and small bowel motility, leading to delayed gastric emptying 1

Clinical Implications

Women who experience morning sickness are significantly less likely to miscarry than women who do not, and those who vomit suffer fewer miscarriages than those who experience nausea alone 5. This suggests morning sickness may serve a protective function during pregnancy.

Management Considerations

Early recognition and treatment of NVP may help prevent progression to hyperemesis gravidarum 1. It's important to treat symptoms consistently rather than only when symptoms emerge (pro re nata), as this helps maintain adequate fluid and calorie intake 6.

Initial management includes:

• Dietary and lifestyle modifications
• Small, frequent, bland meals
• High-protein, low-fat meals
• Identifying and avoiding specific triggers 1

For persistent symptoms, first-line treatments include:

• Ginger (250mg capsule 4 times daily)
• Vitamin B6 (pyridoxine, 10-25mg every 8 hours) 1

Common Pitfalls

1. Delayed treatment: Waiting until symptoms are severe before initiating treatment can lead to dehydration, weight loss, and potentially hyperemesis gravidarum.

2. Inconsistent treatment: Treating symptoms only when they emerge rather than consistently can lead to inadequate fluid and calorie intake 6.

3. Dismissing symptoms: Although common, morning sickness can significantly affect a woman's quality of life and should be taken seriously 4.

4. Missing the diagnosis of hyperemesis gravidarum: This severe form requires prompt medical attention and may necessitate hospitalization for intravenous therapy 4.