Nausea and vomiting affect about 85% of pregnancies and can significantly impact quality of life, particularly during early pregnancy.

"The cause of nausea and vomiting during pregnancy is unknown to this date. Various theories have been proposed, but none of them is conclusive," said Albert T. Liu, lead author for the University of California – Davis study and a professor of obstetrics and gynecology.

"Nausea, vomiting and constipation during pregnancy can significantly diminish the quality of patients' lives. Once nausea and vomiting during pregnancy progress, they can become difficult to control, and sometimes the patient even needs to be hospitalized," Liu said.