Study: Nausea and vomiting symptoms during pregnancy start within a three day timeframe Jan 12 2021 Researchers from the University of Warwick have narrowed the time frame that nausea and vomiting during pregnancy will potentially start to just three days for most women, opening up the possibility for scientists to identify a biological cause for the condition. By measuring the onset of symptoms from a woman's date of ovulation for the first time, rather than last menstrual period, they have demonstrated that symptoms start earlier in pregnancy than previously thought, and within a smaller time frame. Nausea and vomiting in pregnancy, often referred to as pregnancy sickness, which usually ends by 12 -14 weeks of pregnancy is experienced by most women during pregnancy although some will experience it more severely, as in the case of hyperemesis gravidarm when the symptoms can continue throughout the pregnancy. The cause has historically often been seen as psychological but this latest study reinforces the view that the cause is biological and is linked to a specific developmental stage of pregnancy.