Mr Justin Clark
In severe cases there can be dehydration and marked alteration in the composition of electrolytes in the mother's body, as well as vitamin deficiency. These changes can cause headaches, muscle weakness and extreme tiredness.

Her liver can be also affected, leading to jaundice and problems with blood clotting. Dehydration can predispose to a thrombosis - that's a blood clot in a deep leg vein or within the chest. Many women may have 'heartburn' caused by inflammation of the stomach and oesophagus (gullet) but sometimes upper abdominal pain can be severe and, if associated with blood stained vomit, may indicate the possibility of a tear in the gullet from repeated retching and vomiting.

Women and their families should be reassured that most cases can be effectively addressed through relatively simple measures and complications to the mother or her baby are unusual. Prompt rehydration is key, by drinking fluid or, in severe cases, by using a drip. In some stubborn cases, the mother should take Vitamin B1 (thiamine) to prevent rare complications arising from a lack of the vitamin that otherwise would cause confusion, seizures and paralysis. Support and reassurance are important because prolonged, debilitating symptoms can also lead to depression.

Mr Justin Clark
The estimated rates of recurrence of severe sickness (hyperemesis gravidarum) in subsequent pregnancies vary according to how strict the definition of the condition is. What we do know is that women with a past history of the condition are more likely to develop it again, compared to women who have not experienced it.

However, most women do not get such a severe recurrence. There is no strong evidence to support the notion that severe sickness gets easier to manage in subsequent pregnancies once developed. However, I find most experienced mums who have had the condition in a previous pregnancy know a bit more about what to expect and are prepared for it, also taking comfort from the knowledge that the condition usually gets better after the first 14 to 20 weeks and the pregnancy will be otherwise unaffected.

Mr Justin Clark
It is important that women speak to healthcare professionals such as their midwife or GP for assessment and advice. Other conditions, such as urinary tract infections, may cause or worsen the symptoms.

Most women can be managed without the need to go into hospital, with support and reassurance, advice about oral rehydration, diet and lifestyle, and may or may not need a prescription of anti-sickness tablets. If she is really dehyrdrated and the simple measures are not working, she may need to go into hospital. Many hospitals now offer outpatient or day care units specifically to treat this condition. Rehydrating the mum by using a drip, giving her anti-sickness tablets and vitamins, as well as expert advice and ongoing support from experienced nurses, doctors and even fellow sufferers will all help.

All pregnant women will be booked for an ultrasound scan to accurately date the pregnancy, but if the mum is suffering from severe morning sickness her doctor may decide to give her an earlier scan as the sickness may be due to a twin pregnancy or some rare placental problems and it's important to see what's going on. There a several patient support groups accessible via the internet that can also be a valuable source of information and support.