The link between morning sickness and healthy pregnancy

Research Summary
Tugba Colak-Champollion
Contributing writer for Baby Sleep News

Most pregnant women experience morning sickness in the first trimester of pregnancy. Although it is uncomfortable, many doctors think that morning sickness is a good sign suggesting the placenta is developing properly.  On the other hand, an extreme form of morning sickness, hyperemesis gravidarum (HG), which occurs in 0.3-2% of pregnancies, is debilitating and associated with hospitalization during pregnancy. 

HG causes severe vomiting which results in dehydration, electrolyte imbalances, weight loss, and nutritional deficiencies.  Moreover, it can lead to preterm birth and neurodevelopmental delay. Women with HG struggle both emotionally and physically during pregnancy. Unfortunately, there is no cure for this condition. Recently the Duchess of Cambridge, Kate Middleton, a sufferer of HG brought this rare condition into spotlight by going through three difficult pregnancies. 

Despite being a well-documented condition, the cause of HG is unknown.  Observations suggest a genetic basis for it; if your mother or sisters had it, you are 20-30% more likely to have it. 

Two independent studies suggest that too much of the protein, GDF15, which is found in the blood, might contribute to causing HG. The first study, led by Clive Petry, discovered that higher amounts of GDF15 is positively associated with vomiting and nausea during the second trimester of pregnancy connecting this protein to typical morning sickness and more. 

The second study, led by Marlena Fejzo, examined the genome (all the genes) of pregnant women to identify the cause of HG. They analyzed the genomes in two complementary ways. Fejzo’s team first compared the genomes of women who were hospitalized for nausea and vomiting to women who did not report nausea or vomiting during pregnancy.  The research team then focused on genomes of pregnant women who reported a varying degree of vomiting and nausea.  Both analyses showed that two regions in the genome are associated with severe morning sickness.  One region contained the gene for GDF15, which was also identified by Petry’s team, and the other contained the gene for another protein called IGFB7. 

Both proteins are produced at higher levels after implantation (attachment of the fertilized egg to the lining of uterus) and in the developing placenta.  Both influence appetite and are produced less prior to miscarriage. However, these studies suggest that too much of GDF15 and IGFB7 may lead to HG, risking the pregnancy. 

These findings are encouraging steps toward treating HG.  However, the dual role of the proteins in both protecting pregnancy and causing morning sickness and more may make it a challenging task to develop the right drugs to treat the condition.


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