Capital & Coast DHB Women's Health Obstetrics & Maternity Service
Nausea and vomiting are the most common symptoms experienced in early pregnancy, with approximately 50 - 80% of women experiencing nausea and 50% of pregnant women experiencing vomiting. In a smaller number of women the vomiting can be persistent, frequent and severe - in these cases it is known as hyperemesis gravidarum.
Hyperemesis affects 1 to 10 of every 100 women and is diagnosed when the nausea and vomiting are so severe that the woman requires admission to hospital. Hyperemesis most commonly occurs in weeks 8 – 12 and may continue until 20 weeks.
What causes hyperemesis gravidarum?
The exact cause is unknown but it is believed to be due to rising levels of pregnancy hormones such as HCG and oestrogen, which some women seem more sensitive to than others. Emotional factors may contribute to the severity of nausea and vomiting and can be due to worries over social or financial circumstances, feelings surrounding the pregnancy or many other reasons.
Women with twin pregnancies are more likely to get hyperemesis because the hormone levels are higher.
- Hyperemesis Gravidarum (PDF, 338.3 KB)