Morning sickness is basically vomiting and nausea that some women have at initial period of their pregnancy. It is caused due to the rapid rise in hormones during pregnancy. Even though morning sickness is common in the morning hours, but it can happen at any time of the day or it even occur at night. Morning sickness is very common in initial months of pregnancy. Generally it tends to go away later in pregnancy, and it's gone nearly by the second trimester (means after the fourth month of pregnancy). But there is no exact time for it to end because every woman is different, and every pregnancy is also different.
About 80 to 85% of pregnant women experience morning sickness (a period of nausea and vomiting). This is an unpleasant feeling but not at all dangerous. In some cases pregnant women will vomit so badly that they suddenly lose weight and become dehydrated. In this situation they required immediate hospital treatment. This acute stage of morning sickness is known as hyperemesis gravidarum. This situation could be life-threatening if left untreated; it can be easily cured in brief hospital stay. When a woman has morning sickness, it can be so acute that sufferer may feel difficulty in regular works.
While the accurate causes of morning sickness is still unknown, it's perhaps associated to pregnancy hormones. Pregnant women tend to have higher levels of these hormones than others. Morning sickness doesn't strike essentially in morning. Although vomiting is at its most awful for lots of pregnant women in between 9 am and noon, but it can go on through the day, or may even come out in a totally different schedule. Naturally, vomiting is more expected after meals. This is basic problem of pregnancy. A few women begin vomiting from the start days, but usually morning sickness starts after sixth weeks from the end of the last menstruation. Actual vomiting is frequently come first by nausea lasting a week or two.