The exact cause of hyperemesis gravidarum (HG) is unknown.
Things suspected of causing it are:
- hormonal changes during pregnancy
- nutritional problems - a lack of vitamin B6 can make symptoms worse
- having HG in a previous pregnancy, which increases your chance of having it again
If you have another pregnancy after having HG, you should prepare in case you get it again. You might need to spend time in hospital or need extra rest because of HG. You should also talk to your GP about starting anti-sickness medication early.