What Causes Morning Sickness?
Healthcare providers aren't entirely sure what causes morning sickness, or why some pregnant women are afflicted while others go through pregnancy nausea-free. Likely, there isn't just one cause, but a combination of factors that contribute to the condition. Researchers think the most likely causes may include:
- Increased hormone levels. This can help explain why nausea and vomiting are more severe early in pregnancy, when certain hormone levels, such as estrogen and human chorionic gonadotropin (hCG), begin to rise. Also, the timing is right -- nausea and vomiting of pregnancy tends to be worse around the same time the hCG hormone is at its peak.
- Slowing down of the gastrointestinal (GI) tract. During pregnancy, food and other stomach contents move more slowly from the stomach into the intestines and through the intestines out the body. The backup of food could lead to nausea and vomiting.
- Psychological factors. Pregnancy can be a stressful time for many women. All that stress and anxiety may lead to feelings of nausea. Of course, the opposite can be true as well -- nausea and vomiting can definitely cause feelings of stress and anxiety.
Studies have tried to pinpoint certain things that may increase a woman's chances of experiencing nausea and vomiting during pregnancy. In certain studies, younger women, women who smoke, and women who have had more than one pregnancy seemed to have a higher risk. However, other studies haven't shown the same results, so it's difficult to say for certain whether these factors play a role in who does and who doesn't develop nausea and vomiting while pregnant.
Although any woman may develop nausea and vomiting during pregnancy, there is some compelling evidence suggesting certain groups of women may be more prone to the problem. For example, if you had morning sickness during a previous pregnancy, you're unfortunately more likely to have it again. Other women who have a higher risk for developing nausea and vomiting during pregnancy include women who:
- Developed nausea or vomiting as a side effect from estrogen or birth control pills
- Get migraines immediately before or during their monthly menstrual period
- Experience motion sickness
- Have had GI problems in the past, such as ulcers or heartburn.
Studies have also shown that pregnant women with nausea and vomiting are more likely to consume a diet high in carbohydrates and sugar and low in protein. However, these studies are not designed to determine whether such a diet actually causes the problem. Instead, it could be that women who have nausea and vomiting crave carbohydrates and sugar over protein, or eat foods high in carbohydrates and sugars to try to relieve their symptoms.