Nausea and vomiting during pregnancy may protect the unborn baby — to a point.
Morning sickness has been a hot international topic since the recent announcement that the Duchess of Cambridge, the former Kate Middleton, is pregnant for the second time — and once again battling the severe nausea and vomiting that shadowed her first pregnancy.
But while morning sickness itself is a misnomer — with garden-variety nausea and vomiting affecting pregnant women any time — it is also a major understatement of what the duchess is going through. She was diagnosed with hyperemesis gravidarum, or HG, a debilitating and sometimes life-threatening condition that afflicts up to 3% of pregnant women and is characterized by relentless vomiting, dehydration and weight loss.
"The vomiting is violent and nonstop," says Marlena Fejzo, associate research scientist at the David Geffen School of Medicine at
She adds that 15% of those suffering from HG end up terminating their pregnancies. Of those who continue with their pregnancies, an unlucky few have fetuses that die anyway. Fejzo was one of these women. During her second pregnancy, she was hospitalized for severe dehydration at five weeks. For the next two months she vomited constantly, losing excessive weight and becoming so weak, nauseous and dizzy that she couldn't get out of bed.
"I had to stare at the wall and try not to throw up. It was the worst thing that's ever happened to me," Fejzo says.
Her doctor put her on IV fluids, a cocktail of medications and, eventually, tube feeding. Still, her condition deteriorated and finally she began to hemorrhage. Her fetus died in utero at 15 weeks.
After this traumatic experience, Fejzo decided to use her training as a geneticist to investigate HG. She partnered with the Hyperemesis Education and Research Foundation (www.helpher.org), initiating a series of studies looking at genetic components of the disease (women are 17 times more likely to have HG if their sisters suffer from the condition) and risks for mothers and their babies.
"Hyperemesis causes low birth weight and preterm birth, and we've even shown that there is a higher rate of emotional and behavioral disorders in adults that were exposed to HG in utero," says Fejzo. She cites another study that shows HG is correlated with learning and attention problems in children.
These findings contrast with an array of studies showing that less severe nausea and vomiting in pregnancy is correlated with positive pregnancy outcomes. In fact, run-of-the-mill morning sickness appears to signal that a pregnancy is healthy, says Dr. Gideon Koren, pediatrician and director of the Motherisk Program at the Hospital for Sick Children in Toronto.
Though the exact cause of morning sickness (as well as HG) is unknown, Koren says there is consensus that nausea and vomiting in pregnancy are caused by hormonal changes. "What we do not know is what hormones and what changes. …It could be caused by a hormone we haven't identified yet."
He explains that the same hormonal changes that cause nausea and vomiting in pregnancy likely provide the protective effect on the fetus.
Koren recommends that any woman experiencing nausea and vomiting talk to her doctor right away. "It's a slippery slope. Once she begins to throw up, it may be difficult to keep any medication down. Trying to knock it down when it starts is important."
As for the duchess, Fejzo says, "It seems endless and unbearable, so she needs a lot of support. She just has to focus on the outcome, which is hopefully a beautiful and healthy baby."