Nausea and vomiting are common symptoms experienced by 50– 90% of women’s in early pregnancy. ‘Morning sickness’ is a misnomer frequently used to describe nausea and vomiting in pregnancy (NVP), although the symptoms may persist the whole day and/or night. Pregnant women experience these symptoms mainly in the first trimester between 6 and 12 weeks of gestation, few of them continue till 20 weeks of gestation while in few others it continues throughout the pregnancy. The problem peaks at 9-week gestation, and approximately 60% of NVPs resolve by the end of first trimester. In a very small minority of these patients, the symptoms become severe leading to dehydration, weight loss, excessive vomiting, and mandate hospital admission; this condition is known as Hyperemesis Gravidarum.
Fairweather D.V proposed the most widely used definition of Hyperemesis Gravidarum (HG). He defined HG based on the symptoms, vomiting exceeding three times a day with significant ketonurea or weight loss more than or equal to 5% of pre pregnancy weight, electrolytic imbalance or fluid depletion, and onset occurs at 4 to 8 weeks of pregnancy till 14 to 16 weeks. Nausea and vomiting in pregnancy is of multifarious etiology (fluctuating levels of progesterone, estrogens, Thyroid Stimulating Hormone (TSH), slow peristaltic movement of Gastrointestinal (GI) tract); however, the exact mechanism remains still unclear.
Given the uncertainty in treatment of NVPs, both patients and healthcare practitioners often fear the use of antiemetic medications in pregnancy due to the potential risk to fetus and mother. The manifestation of nausea and vomiting in pregnancy is different among each woman, so its management should be tailored similarly. An early treatment of nausea and vomiting is important and beneficial since it prevents a more severe form of occurring, or a possible hospitalization, and prevents both emotional and psychological problems. It is very important for the women and the healthcare providers to understand that a safe and effective NVP treatment benefits both fetus and mother, thus all the treatment options should be open and considered.
Nonetheless, given the widespread prevalence of nausea and vomiting, its adverse effects and effects on psychological conditions of pregnant women, it is necessary to be treated effectively and safely during embryonic and fetal developmental stages. First trimester exposure is important to be assessed to monitor the teratogenic potential of the drug; however, randomized control trials are rarely conducted for pregnant women for ethical reasons. Whereas the epidemiological studies done are observational and lack population strength to establish safety and risk involved. This review will mainly focus on pharmacological drugs used in treatment of NVP, and explore their safety and efficacy and evidence based practice. There have been many studies examining the safety of drugs used in NVPs and few of them are covered in this review. The dietary, lifestyle modifications, and nonpharmacological approaches are not covered in this section.