Pregnancy vomiting due to early pregnancy reactions will usually occur around 5 to 10 weeks of pregnancy when these symptoms of nausea and vomiting will appear.
The symptoms are preceded by menopause, at which point a blood test for hCG will be taken and the value will be significantly higher.
If there is no menopause and there is no increase in hCG and nausea and vomiting occurs, this may be due to gastrointestinal disorders or other systemic disorders causing vomiting in pregnancy and further tests combined with accompanying symptoms are needed to confirm the diagnosis.