Severe nausea during pregnancy can be fatal, yet very little is known about this condition. Hormonal, genetic and socio-economic factors may all play a role.
Almost all women experience some nausea or vomiting when pregnant. Approximately one out of every hundred suffers from acute nausea during pregnancy (hyperemesis gravidarum) and may need hospital treatment to restore hydration, electrolytes and vitamins intravenously.
"At worst, women may die if they go untreated. Many women find that the condition has an adverse effect on their work and family lives," states Åse Vikanes, senior researcher at the Norwegian Institute of Public Health and specialist in gynaecology and obstetrics.
Making up for insufficient research activity
Hyperemesis came under the spotlight earlier this winter when Kate, the Duchess of Cambridge, was hospitalised because of it.
But research projects on this illness have been few and far between. When Dr Vikanes completed her doctoral degree in 2010 with funding from the Research Council of Norway, her thesis was the first in this field in Norway in 70 years.
"This is a relatively common affliction among women and even so it has been difficult to win understanding for the need for research. Not too many years ago, people sincerely believed that the cause could be the woman's subconscious rejection of the child and the child's father. The attitude in part has been that the pregnant woman needs to pull herself together," Åse Vikanes explains.
The real cause behind severe nausea during pregnancy remains unknown and looks to be complex. But there is little to support the idea that the explanation is psychological.
Both hormones and genetics involved
Several studies have shown that elevated levels of oestrogen and the pregnancy hormone, human chorionic gonadotropin (hCG), may be involved. The likelihood is that hormonal, genetic and socio-economic factors all play a part.
In her doctoral project, Åse Vikanes demonstrated that there is wide ethnic diversity in the occurrence of hyperemesis. In addition, the risk is higher among women whose mothers suffered from the syndrome. Non-smokers with a BMI that is higher or lower than the norm also show a higher tendency to experience severe nausea during pregnancy, whereas smoking appears to provide protection from the nausea.
The occurrence of hyperemesis also varies with the mother's age and the gender of the fetus, with younger mothers carrying baby girls at the greatest risk.
Nutrition and physical activity part of the picture
Dr Vikanes and her colleagues are now working to identify more risk factors linked to hyperemesis and to examine possible consequences of the condition on mother and child. Recent research has actually shown that the mother's diet during pregnancy may be significant to the health of the child later in life.
Dr Vikanes is also involved in projects examining the impact of nutrition, physical activity and what can be referred to as "candidate genes." Candidate genes are genes that may cause an individual to be predisposed to illness -- in this case, hyperemesis.
"We need to learn more about this so we can help women who suffer from this condition to get better treatment," Dr Vikanes concludes.
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