Cases' mothers reported slightly less nausea during pregnancy than controls' mothers, and none of the mothers reported exogenous hormone exposure during the index pregnancy.
Researchers have also reported that nausea during pregnancy is related to human chorionic gonadotropin levels, and the absence of these symptoms in early pregnancy may be sign of poor implantation or miscarriage [ 34].
Overwhelming, debilitating nausea during pregnancy is bad enough.
Nearly 90% of mothers experience nausea during pregnancy, with about half actually vomiting.
Zita West Acupuncture has been shown in trials to help with all kinds of nausea, including pregnancy sickness.
Around seven in 10 pregnant women have episodes of nausea during pregnancy; but a smaller number, around one in 50, suffers the kind of extreme sickness, or "hyperemesis gravidarum", experienced by Harrison.
Patrick O'Brien, a spokesman for the Royal College of Obstetricians and Gynaecologists, said: "Nausea during pregnancy can be difficult to treat as the symptoms and severity vary from person to person – some have no problems at all whilst others suffer terribly.
It has been used to counter the nausea of pregnancy and chemotherapy; dental and test-taking anxiety; pain associated with surgery, root canal treatment and childbirth; fear of flying and public speaking; compulsive hair-pulling; and intractable hiccups, among many other troublesome health problems.
While the researchers can't say exactly why the mothers' extreme nausea in pregnancy would affect the children years after birth, the lead author said it may be related to the influence of nutrition on very early development of the embryo and fetus.
However, symptoms of depression have also been associated with nausea during pregnancy [ 7, 9, 60].
