According to US and UK data from public health authorities, morning sickness affects over half of all pregnant mothers. It is generally related to an increase in estrogen levels, low blood sugar counts, and a greater susceptibility to some smells. More often, morning sickness will be present in the early hours of the morning and will ease up somewhat as the day goes on.

Morning sickness is also known as nausea gravidarum, nausea, vomiting of pregnancy (emesis gravidarum), or pregnancy sickness.

At times, morning sickness can be mild. However, the pregnant mother may at other times feel so nauseous that she will vomit.

Even though morning sickness can be extremely unpleasant, it is hardly ever severe enough to cause metabolic derangement. In most cases, morning sickness settles down by the end of the first trimester.

Morning sickness is more likely to occur during the first three months of a pregnancy.