Unlike severe nausea and vomiting of pregnancy (NVP), it is not known whether milder forms of NVP have been associated with psychosocial morbidity. We undertook the study to explore the prevalence of psychosocial morbidity by severity of NVP, and determine whether, after correction for severity of nausea/vomiting, there is a relationship between psychosocial morbidity and women's decisions to take anti-emetics as a reflection of their distress due to NVP. From 1996-97, an NVP Healthline was advertised. Callers underwent semi-structured interviews about both their NVP and associated psychosocial morbidity in a previous pregnancy. Most of the 3201 callers resided in Canada, worked outside the home, reported on planned pregnancy (a median of) 4 years before, and described severe (> 5 episodes/day of) nausea and vomiting. More severe nausea/vomiting was associated with more frequent feelings of depression, consideration of termination of pregnancy, adverse effects on women's relationships with their partners or their partners' everyday lives, and the perceived likelihood that NVP would harm their baby (p < 0.0001). However, all psychosocial factors were reported by a clinically important proportion of women with mild nausea/vomiting (0-1 episodes/day). The severity of vomiting was most closely related to women's decisions to take anti-emetics, but other psychosocial factors were also independently associated with anti-emetic therapy. We conclude that psychosocial morbidity is evident across the spectrum of severity of nausea and vomiting among women with NVP. The severity of nausea or vomiting does not appear adequately to reflect the distress caused by NVP, as reflected by women's decisions to take anti-emetic therapy.