Morning Sickness Health Article

Definition

Morning sickness is the nausea and vomiting experienced during pregnancy, particularly in the first trimester. Although it is called morning sickness, it can and usually does occur at any time of the day or night.

Description

Morning sickness is characterized by extreme nausea and vomiting. It varies widely in intensity; some women experience only minor stomach upset for a very brief time period, while others become so ill that they have difficulty keeping food and fluids down and functioning normally.

In the majority of women, morning sickness symptoms subside toward the end of the first trimester (at 12–14 weeks). However, some women continue to experience nausea well into the second trimester, and some mothers of multiples (twins, triplets, etc.) may have morning sickness throughout their pregnancy.

Causes & symptoms

The exact cause of morning sickness is unknown, but several factors are thought likely to contribute to the illness, including:

• Hormones. The pregnancy hormone hCG enters the bloodstream in high levels in the first trimester of pregnancy. These high hormone levels may trigger activity in the nausea and vomiting center of the brain, which is located in the brainstem.
• Muscle relaxation in the digestive tract. During pregnancy, the muscles of the gastrointestinal tract relax, slowing the digestion somewhat and possibly contributing to nausea.
• Heightened sense of smell. Pregnant women experience a heightened sense of smell during pregnancy that can transform unpleasant odors into unbearable, nausea-producing scents.
• Excessive salivation. The phenomena ptyalism, or excess saliva, is another symptom of pregnancy that can cause nausea in some women.
• Postnasal drip. Many pregnant women experience postnasal drip and/or nasal congestion, triggered by high levels of estrogen in their bloodstream. Estrogen increases the blood flow throughout the body, including the mucous membrane of the nose. This postnasal drip contributes to upset stomach in many pregnant women.