Also, not every woman will experience nausea the entire duration of the first trimester. It could last only a couple of weeks or come and go throughout the first few months. Many refer to nausea during pregnancy as morning sickness, leading women to believe they will only experience nausea in the mornings. In fact, research shows that âmorning sicknessâ actually occurs more often throughout the entire day, rather than just in the early hours. Managing nausea during pregnancy.