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Nausea and vomiting in pregnancy - Background information
What are the complications?
Maternal complications:
- Most women with nausea and vomiting in pregnancy do not experience severe complications. However, the symptoms can significantly affect their lives, in terms of [Davis, 2004]:
- Loss of productivity at home and in employment.
- Psychosocial morbidity (e.g. depression), especially in women with hyperemesis gravidarum.
- Medical complications are more likely to occur in women with severe vomiting or hyperemesis gravidarum and include [Nelson-Piercy, 1998; Kuscu and Koyuncu, 2002; ACOG, 2004; Davis, 2004]:
- Metabolic complications:
- Weight loss.
- Dehydration.
- Acidosis.
- Abnormal liver function test results.
- Hyponatraemia (plasma sodium levels < 120 mmol/L), which may cause lethargy, seizures, and respiratory arrest.
- Vitamin deficiencies (e.g. pyridoxine [vitamin B6]; cyanocobalamin [vitamin B12], which may cause peripheral neuropathy; and thiamine [vitamin B1], which may cause Wernicke's encephalopathy).
- Mechanical complications:
- Retinal haemorrhage.
- Splenic avulsion.
- Mallory–Weiss tears or oesophageal rupture.
- Pneumothorax.
- The combination of immobility and dehydration associated with hyperemesis gravidarum may increase a woman's risk of venous thromboembolism [CEMACH, 2007].
- Today, maternal death from nausea and vomiting is very rare, but until 60 years ago, nausea and vomiting was an important cause of maternal mortality [ACOG, 2004].
Fetal complications:
- Mild or moderate nausea and vomiting have little apparent effect on pregnancy outcome; nausea and vomiting may even be predictors of successful pregnancy outcome [Davis, 2004]:
- A lower rate of miscarriage has been documented among women with nausea and vomiting during pregnancy compared with controls. This is thought to be related to robust placental synthesis in a healthy pregnancy [ACOG, 2004].
- In women with hyperemesis gravidarum, an increased risk of malformations is unlikely. However, a higher incidence of low birthweight babies has been documented, particularly if the mother had low pregnancy weight gain (< 7 kg) [Nelson-Piercy, 1998; ACOG, 2004; Dodds et al, 2006].
- Fetal death is very rare and is usually limited to extreme cases of hyperemesis [ACOG, 2004].
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