The onset of morning sickness is dreaded by most mums-to-be, but could it have an upside for mums and their babies?
Canadian researchers found that women not suffering from nausea and vomiting in pregnancy were between three and ten times more likely to miscarry in the first three months of pregnancy compared with women who had morning sickness symptoms.
Babies born to mothers who had morning sickness were also less likely to have birth defects, be born prematurely, or be small or have a low birth weight.
They also scored higher on IQ tests when aged between three and seven years.
The study, conducted at the Hospital for Sick Children in Toronto and published in the August issue of Reproductive Toxicology showed as many as 85% of pregnant women develop morning sickness, with symptoms ranging from mild to severe.
Rapid increases in human gonadotropin, a hormone released by the placenta, are believed to help trigger the symptoms. At the same time, relatively high levels of the hormone, and possibly other hormones not yet identified, may contribute to a more favorable prenatal environment, the researchers said.
The report’s author Gideon Koren, said that taking drugs to reduce symptoms of nausea and vomiting doesn’t affect a woman’s hormonal levels and therefore shouldn’t alter any positive effects associated with morning sickness.
The risk of miscarriage was more than three times as high in women without symptoms of nausea and vomiting as in those with symptoms. Women 35 years old or older, who generally have a relatively high risk for miscarriage, appeared to benefit the most from the “protective effect” associated with morning-sickness symptoms, the study said.
Nausea and vomiting during pregnancy were associated with a reduced risk for low birth weight and short body length. Women with morning-sickness symptoms also had fewer preterm births: 6.4% compared with 9.5% for those without symptoms, one of the underlying studies found.
The risk of birth defects was reduced by between 30% and 80% in infants of mothers with symptoms and these children also scored higher in IQ tests later in life.