STUDY: Genes likely play key role in severe morning sickness

Genes involved in the development of the placenta play a key role in causing about 2 percent of pregnant women to suffer severe morning sickness symptoms of nausea and vomiting, according to a UCLA study released on Wednesday.

Most women experience some morning sickness during pregnancy, but only a small percentage show the most severe symptoms. Sometimes the condition is so serious that hospitalization is required. Known as hyperemesis gravidarum, the condition is the same one that Kate Middleton, the Duchess of
Cambridge, endured in her pregnancies.

The study led by researchers at UCLA and published in the journal Nature Communications identified two genes associated with hyperemesis gravidarum, the cause of which has not been determined in previous studies.

The genes, known as GDF15 and IGFBP7, are both involved in the development of the placenta and play important roles in early pregnancy and appetite regulation, according to UCLA.

"It has long been assumed that the pregnancy hormones, human chorionic gonadotropin or estrogen, were the likely culprits of extreme nausea and vomiting, but our study found no evidence to support this," Marlena Fejzo, the study's first author, said.

Fejzo, an associate researcher at the David Geffen School of Medicine at UCLA, said the genes, coincidentally, are linked to cachexia, a weight loss and muscle wasting condition that leads to death in about 20 percent of cancer patients and has similar symptoms to hyperemesis gravidarum.

Fejzo said she herself had hyperemesis gravidarum and lost a pregnancy to the condition in 1999. The debilitating symptoms can include rapid weight loss, malnutrition and dehydration due to persistent nausea and/or vomiting.

Current medications to treat the condition are largely ineffective and can lead to serious health consequences for both mother and baby, Fejzo said. The condition is the second leading cause of hospitalization during pregnancy. Women often require intravenous fluids and, in the most severe
cases, feeding tubes.