Management of nausea and vomiting in pregnancy.

Nausea and vomiting are the most common symptoms of pregnancy. As a result many medical practitioners will encounter this problem and should be familiar with the appropriate investigations and current treatment options. Nausea and vomiting affect 50-90% of pregnant women, and in about 35% of these women symptoms are of clinical relevance, with both physical and psychosocial sequelae. Although colloquially referred to as “morning sickness,” for many women symptoms persist over the whole day, with a broad spectrum of severity ranging from occasional nausea to fulminant and intractable vomiting. Nausea and vomiting begin in the first trimester, at about six to eight weeks’ gestation, typically peaking at about nine weeks’ gestation and settling by about 12 weeks. Only a minority of women have symptoms after 20 weeks of gestation. Adequate oral hydration and avoidance of dietary triggers are often sufficient, but a proportion of women with severe and protracted nausea and vomiting will need antiemetic drugs. A more severe form of nausea and vomiting in pregnancy affects less than 1% of women and is referred to as hyperemesis gravidarum. Different definitions of hyperemesis gravidarum exist, but the important features are intractable vomiting associated with weight loss of more than 5% of pre-pregnancy weight, dehydration, electrolyte imbalances, ketosis, and the need for admission to hospital. Before reaching a diagnosis of hyperemesis gravidarum, exclude other causes of severe nausea and vomiting (box 1). Carefully assess and treat all women who present with severe nausea and vomiting in pregnancy because this may obviate the need for admission. In hyperemesis gravidarum, many women will need to be admitted to hospital so that they can receive intravenous rehydration and parenteral antiemetic drugs to avoid serious maternal and fetal morbidity (box 2). Maternal complications of severe hyperemesis gravidarum include Wernicke’s encephalopathy as a result of thiamine (vitamin B-1) deficiency, and fetal complications include fetal growth restriction. 4