Nausea and vomiting in pregnancy (NVP)—often called “morning sickness”—is very common, especially in the first trimester. Here are the main reasons: 1. Hormonal Changes hCG (human chorionic gonadotropin) Levels rise rapidly in early pregnancy. Higher hCG levels are strongly associated with nausea (e.g., in twins or molar pregnancy). Estrogen Increases during early pregnancy and can slow stomach emptying. May heighten sense of smell, triggering nausea. Progesterone Relaxes smooth muscles, including the gastrointestinal tract. Slows gastric emptying and causes bloating → nausea. 2. Enhanced Sense of Smell & Taste Pregnancy heightens sensitivity to odors, making certain smells (food, perfume, smoke) trigger nausea. 3. Gastrointestinal Sensitivity Slowed gut motility and gastric emptying. Acid reflux due to relaxation of the lower esophageal sphincter. 4. Evolutionary/Protective Theory Some scientists believe nausea protects the fetus by preventing the mother from ingesting harmful foods during organ formation. 5. Stress and Fatigue Tiredness, emotional stress, or lack of sleep can worsen nausea. 6. Vitamin or Mineral Imbalances Low levels of vitamin B6 may contribute. 7. Low Blood Sugar In early pregnancy, metabolism changes and can lead to symptoms when glucose levels drop. 8. Helicobacter pylori Infection Some evidence links this stomach bacterium to more severe nausea/vomiting. 9. Serious Conditions (Less Common) These need medical attention: ⚠️ Hyperemesis gravidarum Severe, persistent vomiting