Abstract
It is a puzzling fact that emesis might occur in one pregnancy, whereas other pregnancies in the same woman could be either free or again associated with nausea. Pregnancy-associated hormones are believed to cause nausea, possibly through effects mediated via the liver. in 43 women who applied for a legal abortion in early pregnancy the occurrence of nausea was recorded and the position and size of the corpus luteums were measured by means of ultrasound. It was found that emesis was associated with corpus luteum located predominantly on the right side, while the non-emetic pregnancy often had a left-sided corpus luteum. It is suggested that the venous drainage, which differs between the right and the left side, may be responsible for the fact that the same woman can either suffer from or be free from nausea during pregnancy. Ovarian vein insufficiency, being more common in multigravidity, may also explain why nausea is more common in multigravidae.