The fact of the matter is that there’s no hard and fast rule about when morning sickness will end. It can be very different for every pregnancy. Notice that we said every “pregnancy,” and not every “woman.” You see, you might actually have very different morning sickness experiences from one pregnancy to the next. All of that being said, we can look at some overall trends and see that morning sickness, on average, will end by around week 12 of your pregnancy.
To be sure, there are women for whom morning sickness lasts longer than the 12th week of pregnancy. There are some women who suffer from morning sickness well into the second trimester. Those are fairly rare, however. Really, morning sickness after week 12 is considered to be rare overall.
Morning sickness tends to begin at about the sixth week of pregnancy. What this means is that, for most women, you can count on about six weeks of morning sickness. Some women might start sooner, of course, and some might start later. A surprising 30 percent of women never experience any morning sickness, as a matter of fact.
While researchers aren’t completely certain, morning sickness may be related to the levels of the pregnancy hormone hCG (human chorionic gonadotropin) in your body. This is the same hormone that a pregnancy test looks for. HCG rises in your system, at first enough so that a pregnancy test can detect it, and then moreso between weeks six and 12 of pregnancy. The rise and fall of hCG seems to correspond very well to the rise and fall of morning sickness, although again this isn’t necessarily a conclusive thing yet.
If your morning sickness doesn’t end by around the time you start your second trimester, you should probably talk to your doctor. It could actually be that your upset stomach or nausea has a different cause, quite apart from morning sickness. You should also talk to your doctor if your nausea is severe and you’re having trouble keeping food down, as this will dramatically affect the nutrition that both you and your growing baby are getting.