Nausea and vomiting of pregnancy is the most common medical condition in pregnancy. Relatively little research has been conducted on this condition, and much of it is based on women's reports. Determinants that affect women's reports of their nausea and vomiting of pregnancy symptoms have not been elucidated. The purpose of this study was to assess the accuracy of recall by women of their symptoms of nausea and vomiting of pregnancy.

Two hundred women who called the Motherisk nausea and vomiting of pregnancy counseling line in Toronto were asked about the severity of their nausea and vomiting of pregnancy symptoms with the use of the pregnancy unique quantification of emesis and nausea system (PUQE). The patients were asked the same questions again during a follow-up call, which took place up to 16 weeks later.

There was a recall (or reporting) bias for nausea and vomiting, with women reporting significantly more severe symptoms during their follow-up call than they had reported originally. Multivariate analysis revealed that the severity of the symptoms affected the accuracy of recall positively, whereas the time that has elapsed affected it negatively.

Retrospective evaluation of nausea and vomiting of pregnancy symptoms may produce a recall bias, which may distort the evaluation of the therapeutic effectiveness of antiemetics.