编者按： Pregnant women，known as mommy-to-be，experience various pregnancy symptoms such as morning sickness，swelling，changes in dietary preferences，and more. However，one thing that is particularly fascinating is that although all pregnant women undergo similar changes，their reactions can differ greatly. For instance，while some women experience severe nausea，others have no symptoms at all.
A few months ago，a pregnant woman told me about her discomfort due to severe morning sickness. She had difficulty eating，and sometimes even vomited up bile. She complained that her friends，who were also pregnant，had no such issues. They even joked that they felt like they didn"t even experience pregnancy because they lacked morning sickness.
So，why do pregnant women experience different levels of nausea？
Hormonal fluctuations during pregnancy affect nausea
The exact cause of morning sickness is still unknown，but medical professionals generally attribute it to the numerous changes that occur in a woman"s body during pregnancy. In some clinical cases，pregnant women with severe morning sickness had the highest levels of human chorionic gonadotropin（HCG）in their bodies.
This means that if a pregnant woman has a higher HCG level than other women，she may experience more severe morning sickness. On the contrary，if the HCG level is lower，the nausea may be less prominent.
Nausea is related to a woman"s physical condition
A woman"s physical condition also plays a role in her pregnancy nausea. Some women become more sensitive to tastes and smells during pregnancy，which can trigger vomiting. For example，a woman who usually enjoys seafood may now find it repulsive due to an increased sensitivity to fishy smells.
Additionally，some women may experience vomiting due to increased physical stress，such as eating cold or spicy foods that irritate their stomachs.
Psychological factors can also cause nausea