Most women naturally experience nausea and vomiting during pregnancy due to hormones. However, two specific genes are likely to blame for a condition that increases the severity of those symptoms, according to a new study.

About 2 percent of soon-to-be mothers, like Kate Middleton the Duchess of Cambridge, suffer from hyperemesis gravidarum (HG), which causes severe nausea and vomiting during pregnancy. 

Middleton's high-profile status has created more awareness for HG. She has been hospitalized during each of her three pregnancies. 

Dr. Marlena Fejzo and her team at the David Geffen School of Medicine at UCLA, have discovered two genes associated with HG, according to a new study published Wednesday in the journal Nature Communications.

Scientists compared the variation in DNA from pregnant women with no morning sickness symptoms to those with HG to determine any similarities. 

Experts found that DNA variation around the genes known as GDF15 and IGFBP7 were linked to HG. Past research pointed to the condition possibly being hereditary.

"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," Fejzo, the author of the study said.

The two genes GDF15 and IGFBP7 are crucial during early pregnancy and are linked to placenta development and appetite regulation. HG can cause "rapid weight loss, malnutrition and dehydration due to persistent nausea and/or vomiting," the study said.

Fejzo said the two genes exist in cachexia, a weight loss condition responsible for deaths in about 20 percent of cancer patients. The disorder causes symptoms akin to HG.

Fejzo, who in 1999 lost her baby due to the condition, looked to find a solution. "It is my hope that one day a medication that affects this pathway will be used to successfully treat and possibly cure hyperemesis gravidarum," she said. 

Thus far, treating HG has been ineffective and further work is required as experts look to determine whether GDF15 and IGFBP7 protein levels can safely be decreased during pregnancy to diminish symptoms.