Hyperemesis Gravidarum: What to Expect when You are Expecting…Not!

Hyperemesis gravidarum (HG), severe nausea and vomiting of pregnancy, occurs in 0.3–2% of pregnancies and is associated with maternal and fetal morbidity. The cause of HG remains unknown, but familial aggregation and results of twin studies suggest that understanding the genetic contribution is essential for comprehending the disease etiology. Here, we conduct a genome-wide association study (GWAS) for binary (HG) and ordinal (severity of nausea and vomiting) phenotypes of pregnancy complications. Two loci, chr19p13.11 and chr4q12, are genome-wide significant (p < 5 × 10−8) in both association scans and are replicated in an independent cohort. The genes implicated at these two loci are GDF15 and IGFBP7 respectively, both known to be involved in placentation, appetite, and cachexia. While proving the casual roles of GDF15 and IGFBP7 in nausea and vomiting of pregnancy requires further study, this GWAS provides insights into the genetic risk factors contributing to the disease.

In the United States, hyperemesis gravidarum is the most common cause of hospitalization during the first half of pregnancy and is second only to preterm labor for hospitalizations in pregnancy overall. In approximately 0.3-3% of pregnancies, hyperemesis gravidarum is prevalent and this percentage varies on account of different diagnostic criteria and ethnic variation in study populations. Despite extensive research in this field, the mechanism of the disease is largely unknown. Although cases of mortality are rare, hyperemesis gravidarum has been associated with both maternal and fetal morbidity. The current mainstay of treatment relies heavily on supportive measures until improvement of symptoms as part of the natural course of hyperemesis gravidarum, which occurs with progression of gestational age. However, studies have reported that severe, refractory disease manifestations have led to serious adverse outcomes and to termination of pregnancies.