'Morning sickness' may lower miscarriage risk: study

'Morning sickness' may lower the risk of miscarriage in women, according to a new study which suggests that nausea and vomiting during pregnancy protects the foetus against toxins and disease-causing organisms.
Nausea and vomiting that occurs in pregnancy is often called "morning sickness," as these symptoms typically begin in the morning and usually resolve as the day progresses.
For most women, nausea and vomiting subside by the fourth month of pregnancy. Others may have these symptoms for the duration of their pregnancies.
The cause of morning sickness is not known, but researchers have proposed that it protects the foetus against toxins and disease-causing organisms in foods and beverages.

"It's a common thought that nausea indicates a healthy pregnancy, but there was not a lot of high-quality evidence to support this belief," said the study's first author Stefanie N Hinkle from National Institute of Child Health and Human Development (NICHD) in the US.
"Our study evaluates symptoms from the earliest weeks of pregnancy, immediately after conception, and confirms that there is a protective association between nausea and vomiting and a lower risk of pregnancy loss," said Hinkle.

For their study, Hinkle and her colleagues analysed data from the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial, in which researchers tested whether taking daily low-dose aspirin prevents women who experienced one or two prior pregnancy losses from experiencing a future loss.

The researchers looked at data from all the women in the study who had a positive pregnancy test.
The women kept daily diaries of whether they experienced nausea and vomiting in the second through the eighth week of their pregnancies and then responded to a monthly questionnaire on their symptoms through the 36th week of pregnancy.
Researchers noted that most previous studies on nausea and pregnancy loss were not able to obtain such detailed information on symptoms in these early weeks of pregnancy.
Instead, most of studies had relied on the women's recollection of symptoms much later in pregnancy or after they had experienced a pregnancy loss.

In the EAGeR trial, a total of 797 women had positive pregnancy tests, with 188 pregnancies ending in loss.
By the 8th week of pregnancy, 57.3 per cent of the women reported experiencing nausea and 26.6 per cent reported nausea with vomiting.
The researchers found that these women were 50 to 75 per cent less likely to experience a pregnancy loss, compared to those who had not experienced nausea alone or nausea accompanied by vomiting.
The study appears in the journal JAMA Internal Medicine.