Morning sickness affects around 80 percent of all pregnant females. Women who use hormonal contraception or HRT (hormone replacement therapy) may also have symptoms similar to morning sickness.

In the vast majority of cases, morning sickness, although an unpleasant experience, has no health risk for the baby and is a regular part of pregnancy. In fact, some studies indicate that morning sickness during pregnancy can be a sign of a healthy pregnancy, with lower rates of miscarriages and stillbirths, compared with pregnancies with no nausea or vomiting.