When does morning sickness typically increase in pregnancy?

Morning Sickness Timeline in Pregnancy

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

Typical Timeline of Morning Sickness

• Onset: Symptoms usually begin at 4-6 weeks of gestation 1
• Peak intensity: Symptoms reach maximum severity at 8-12 weeks of pregnancy 1, 2
• Resolution: For most women (approximately 80%), symptoms improve or disappear by around week 14 2
• Extended cases: In some women, symptoms may persist until week 20 or beyond 1, 2

Prevalence and Severity

• Approximately 80% of pregnant women experience some degree of nausea and vomiting during pregnancy 2
• Despite the name "morning sickness," symptoms can occur at any time of day or night 2
• Severity distribution:
  • 20% of women have no symptoms 3
  • 28% experience nausea without vomiting 3
  • 52% experience both nausea and vomiting 3

Progression to Hyperemesis Gravidarum

• For 0.3-2% of pregnant women, morning sickness can progress to hyperemesis gravidarum, a more severe condition 1
• Hyperemesis gravidarum is characterized by:
  • Intractable vomiting
  • Weight loss >5% of pre-pregnancy weight
  • Dehydration and electrolyte imbalances 1
• Timing of hyperemesis gravidarum:
  • Usually starts before week 22 of gestation
  • By week 16, symptoms resolve in >50% of affected women
  • By week 20,80% of affected women improve
  • In 10% of cases, symptoms persist throughout pregnancy and occasionally into the postpartum period 1

Clinical Implications

• Early intervention is crucial to prevent progression to hyperemesis gravidarum 4
• Treatment should be consistent rather than only when symptoms emerge (pro re nata) 5
• When symptoms improve, medication doses should be decreased gradually rather than stopped abruptly 5

Management Considerations

• First-line non-pharmacologic approaches include:
  • Diet modifications (small, frequent, bland meals; BRAT diet)
  • Avoiding trigger foods and strong odors
  • Ginger (250 mg capsule 4 times daily) 1, 4
• If non-pharmacologic approaches fail, pharmacologic therapy may include:
  • Doxylamine and pyridoxine combinations (available in 10 mg/10 mg and 20 mg/20 mg formulations)
  • H1-receptor antagonists such as doxylamine, promethazine, and dimenhydrinate 1, 4

Common Pitfalls

• Assuming symptoms only occur in the morning, when they can occur at any time 2
• Treating symptoms only when they emerge rather than consistently 5
• Stopping treatment abruptly when symptoms improve rather than tapering gradually 5
• Failing to recognize that morning sickness may serve a protective function for the embryo by causing women to avoid potentially harmful foods 6