Mothers are more likely to suffer from serious morning sickness if they are pregnant with a girl, researchers claim. A study of over a million pregnancies in Norway between 1977 and 1985 showed there was a greater risk of the condition for women who were carrying a female child.
Though there were more births of boys during the period studied, there was a higher chance of mothers-to-be of girls being admitted to hospital suffering from hyperemesis gravidarum - serious nausea and vomiting during the first three months of pregnancy.
The female to male ratio of hospital admissions was 56:44, according to the research carried out by Dr Johan Askling at Stockholm's Karolinska Institute. The cause of morning sickness is not known, but it is thought to be related to increased production of a pregnancy-related hormone called human chorionic gonadotropin.
Dr Michael De Swiet at the Institute of Obstetrics and Gynaecology at Queen Charlotte's and Chelsea Hospital, London, said the size of the study meant its results were significant."There could be all sorts of explanations," he said. "Morning sickness is something to do with hormones - girl babies may produce different hormones, that could be part of the problem.