Nausea during early pregnancy, also called morning sickness, might be a good sign. Studies have shown that pregnant people with nausea and vomiting during the first trimester have a lower risk of miscarriage than do pregnant people without these symptoms.

What's the connection? Nausea and vomiting during early pregnancy may signal the rise in hormones within the body that's needed for a healthy pregnancy. Research suggests that nausea and vomiting during pregnancy might be due to the effects of a hormone made by the placenta. That hormone is called human chorionic gonadotropin (HCG).

The body begins making HCG shortly after a fertilized egg attaches to the uterine lining. Pregnant people who have severe morning sickness, called hyperemesis gravidarum, have higher HCG levels than other pregnant people do. People pregnant with twins or multiples also have higher HCG levels. They are more likely to have morning sickness too. Estrogen, another hormone that rises during pregnancy, also is linked with more-severe morning sickness.

High pregnancy hormone levels aren't always associated with nausea and vomiting, however. And some research suggests that nausea and vomiting during pregnancy could be related to the growth of the placenta.

It's important to keep in mind, too, that not having nausea and vomiting during pregnancy usually isn't cause for concern. Many people have healthy pregnancies without morning sickness.