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Extracted from Myles Textbook for Midwives 15th Edition. Diane M. Fraser, Margaret A. Cooper (Eds). London; Churchill Livingstone: 2009. Courtesy Elsevier.
Nausea and vomiting are common symptoms in early pregnancy, usually starting between 4 and 10 weeks' gestation and resolving before 20 weeks. Hyperemesis gravidarum is defined as persistent pregnancy-related vomiting associated with weight loss and >5 per cent of total body mass and ketosis. Affecting 0.3-3 per cent of all pregnant women, this is associated with dehydration, electrolyte imbalance and thiamine deficiency. (See Hyperemesis gravidarum) The impact of nausea and vomiting on the woman and her daily life should not be underestimated. The midwife should enquire of all women attending for early antenatal care whether they are experiencing nausea or vomiting. If vomiting is mild to moderate, and not causing signs of dehydration, then usually reassurance and advice will be all that is necessary. Simple measures include:
Antiemetic therapy is reserved for those women who do not settle on supportive measures, or who persistently relapse. The use of antiemetics in pregnancy received widespread publicity when links were found between thalidomide and severe malformations of children born to mothers who had taken the drug for morning sickness. Currently antihistamines are the recommended first line treatment for nausea and vomiting in pregnancy - no antiemetic is approved for this indication. Ginger is a well-known traditional herb remedy for sickness and there is considerable research to demonstrate that it is an effective antiemetic. However, it is not suitable for all women and may exacerbate nausea and cause heartburn. Ginger biscuits should not be advised as any temporary improvement is attributable to their sugar content, and they contain insufficient ginger to have any real therapeutic effect. There is no evidence for the effectiveness of homeopathic remedies. The use of travel sickness wristbands may be useful for some women, and acupuncture can also be effective.
Nausea in labour
Opiate drugs, including pethidine, diamorphine or meptazid, are commonly used for pain relief in labour but side effects include nausea, vomiting and drowsiness in the mother and depression of the baby's respiratory centre at birth. An antiemetic agent is sometimes given at the same time to reduce nausea.