Why nausea and vomiting occur in first trimester of pregnancy?
Due to high level of beta HCG hormone which secreted by trophoplast from placenta
HCG, Estrogen is another hormone that rises during early pregnancy and could contribute to queasiness. A sensitive stomach could be made worse while trying to adapt to the changes of pregnancy. Stress or fatigue is suggested to cause a physical reaction within the body, leading to nausea and vomiting.