Nausea and vomiting of pregnancy

NVOP, often referred to as morning sickness, is a common condition affecting the majority of pregnancies. It typically presents in the first trimester and is characterized by mild-to-moderate nausea and vomiting. HG is a more severe form of NVOP characterized by excessive, persistent nausea and vomiting leading to dehydration, electrolyte imbalance, weight loss, and hospital admission.

The pathophysiology of NVOP is not fully understood, but it is believed that a combination of hormonal changes, gastric dysrhythmias, and heightened olfactory and gustatory sensitivity may contribute to its development. Pregnancy-related hormones such as progesterone, estrogen, and hCG have been widely studied, and other hormones such as leptin, placental GH, prolactin, thyroid, and adrenal cortical hormones have also been implicated. Additionally, infectious, immunological, psychological, metabolic, and anatomical factors may also play a role in its onset.

Nausea during pregnancy is reported in about 50-80% of individuals, with nausea and vomiting occurring in approximately 50%, and HG affecting about 0.3-3% of pregnant individuals.

Risk factors for NVOP and HG include a history of these conditions in previous pregnancies, multiple pregnancy, and maternal age. Other factors such as obesity, dysmenorrhea, motion sickness, migraine, and a history of psychiatric disorders have also been associated with NVOP and HG.

Clinically, NVOP is characterized by mild-to-moderate nausea and vomiting, typically developing in the first trimester of pregnancy. HG is distinguished by severe nausea and vomiting leading to dehydration, orthostatic symptoms, metabolic and electrolyte imbalance, weight loss, and eventually necessitate hospital admission. Both NVOP and HG can significantly impact the patient's QoL due to persistent symptoms.

The prognosis of NVOP is generally good, with symptoms often resolving with lifestyle and dietary changes, and more severe cases responding to safe and effective treatments. The prognosis of HG is more variable, with some patients experiencing symptoms throughout their pregnancy.