Study reveals morning sickness risks
on 30/01/2013 00:00:00
The Duchess of Cambridge was admitted to the King Edward VII Hospital in London in December, suffering from the rare illness which causes severe vomiting during pregnancy.
The condition is most common in the first 12 weeks and often eases off in the middle trimester.
A few weeks ago, St James's Palace confirmed that Ms Middleton, whose baby is due in July, is continuing to feel better.
The study, published in BJOG: An International Journal of Obstetrics and Gynaecology, looked at data from the Swedish Medical Birth Register between 1997 and 2009.
Data from 1,155,033 women showed that 1.1% suffered from hyperemesis gravidarum before they were 22 weeks' pregnant.
Researchers compared data concerning normal pregnancies to women who suffered the condition in the second trimester - or women who were admitted to hospital with the illness between 12 and 21 weeks' pregnancy.
Women who had the condition in the second trimester had a doubled risk of pre-term pre- eclampsia.
They also had a threefold risk of placental abruption - 0.4% compared to 1.1% - and a 39% increased risk of having a small baby.
Co-author of the study Marie Bolin, of Uppsala University, said: "The results indicate that pregnancies with hyperemesis gravidarum in the second trimester demand an increased alertness and supervision during the pregnancy for development of any adverse outcomes associated with abnormal placentation.
"Further research is needed to consider the best treatment and techniques for surveying blood pressure and fetal growth in these high risk women."