Researchers estimate that as much as 75 percent of all pregnant women experience morning sickness. In fact, for some women, morning sickness may be the indicator that they're pregnant.
Despite being called ‘morning sickness,' this pregnancy discomfort can happen at any time during the day, though many pregnant women report symptoms in the morning. Some mothers-to-be report nausea or vomiting brought on by specific foods or smells, especially during their first trimester. But researchers say this condition may actually protect the mother and baby.
The baby is very small during the first trimester. Even at the tail end of this gestation period, around week 14, the baby is only the size of a lemon. To protect the delicate fetus, the mother's body is especially sensitive to stimuli that may be harmful. This means that even trace amounts of certain foods or smells can trigger a reaction to prevent the fetus from exposure to toxins. As the baby develops, the sensitivity is lowered, which is why most morning sickness symptoms go away at the end of the first trimester.
Researchers say a modest amount of morning sickness is actually a good sign that mother and baby are doing well. And in fact, they found that pregnant women who don't experience morning sickness at all have a higher risk of miscarriage.