Study explores possible cause of morning sickness in expectant mothers

Study reveals new causes to morning sickness

Researchers believe they know why many women experience nausea during pregnancy. FOX 7 Austin's Rebecca Thomas talks with a local doctor about the new study in this Health Beat.

AUSTIN, Texas - Many women deal with nausea, also known as morning sickness, during pregnancy. Now researchers think they know why that is.

Dr. Shahryar Kavoussi, reproductive endocrinologist with St David's South Austin Medical Center, joins FOX 7 Austin's Rebecca Thomas in this HealthBeat.

REBECCA THOMAS: So there's this new study. Researchers say women who are exposed to higher levels of a hormone called GDF 15 before they become pregnant are less likely to deal with nausea when they do become pregnant. What role does this hormone play in terms of nausea or lack thereof, during pregnancy?

DR. SHAHRYAR KAVOUSSI: So GDF 15 is an acronym for growth differentiation factor 15. That's a hormone that affects the brain stem. And most women are going to have very low levels of GDF 15 in the non-pregnant state. So the fetus actually will produce the fetus. And the placenta produces this hormone during pregnancy. And a woman whose body is not used to high levels of this GDF 15 will be exposed to it during the pregnancy. And that's the association with nausea and vomiting. Then that increases with increased concentration of GDF 15 in the maternal bloodstream during pregnancy.

REBECCA THOMAS: So a lot of women deal with at least some form of this. A less common but more severe form of nausea during pregnancy is hyperemesis gravidarum. So is the level of GDF 15 exposure related to this as well?

DR. SHAHRYAR KAVOUSSI: Yes, Rebecca, it is. So in cases of hyperemesis gravidarum, which happens in about 2% of pregnancies or so, as opposed to the nausea, vomiting, which happens about 70%, mostly in a mild form. Hyperemesis is very severe, and it is with elevated GDF 15. And the studies show that as well, the study out of USC and Cambridge shows this. Um, and also to address what you asked earlier about, um, high levels of GDF 15 before pregnancy and not having nausea and vomiting. There's an example of this. There are some people that have beta thalassemia, which is a blood disorder genetically inherited. And some women have this thalassemia, and they have high GDF 15 levels in the non-pregnant state. So their bodies use that. And when they're pregnant they don't have nausea and vomiting. It's very interesting actually.

REBECCA THOMAS: That is very interesting. I know in addition to being an unpleasant feeling, morning sickness, what are some of the medical concerns about nausea in pregnant women, especially the severe form?

DR. SHAHRYAR KAVOUSSI: Right. So most women who have nausea, vomiting in pregnancy are going to have a mild form where it's definitely unpleasant, as you mentioned. And, you know, it's a quality of life issue temporarily and try to mitigate it with treatments. But there was a severe form which, as you're saying, I mean, you can have some effects. A woman may not be able to drink fluids and may not be able to eat food effectively and may not be able to hold down drinks and food. And then they have weight loss, and they can have electrolyte imbalances and have low potassium, which needs to be replaced. They may be hospitalized and there can be effects like that. The fetus actually can…there's some conflicting data in the literature saying there may be low birth weight. Some data says no, but that is a potential complication as well.

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REBECCA THOMAS: How is nausea during pregnancy treated now whether it's minor or severe?

DR. SHAHRYAR KAVOUSSI So I think the first line for our pregnant patients that are in the first trimester who have nausea, vomiting in pregnancy, um, they're taking vitamin B6, and they can take that alone, or they can take it with a combination of Unisom as well. And that helps. It's very effective for most patients and [for] some patients it's not very effective. There are other pharmacologic medications as well. So women can take Phenergan, which makes them very tired. So there's a bad side effect of being tired with that medicine. There's also Zofran which some weak data suggests maybe a increased risk, small increased risk of cleft palate in the fetus, cleft palate or cardiac defects. So some people are shying away from it. There's not enough convincing data for sure that will cause those problems, but those are some modalities. There's also the idea of taking prenatal vitamins a month before being pregnant, or sooner, because there is some data suggesting that there's going to be a lower nausea, vomiting, incidence and severity if you take prenatal vitamins a month before getting pregnant because of the vitamin B6 that's in the prenatal vitamins.

REBECCA THOMAS: So looking at GDF 15, how might the new research on this help pregnant women in the future in terms of treatment or prevention?

DR. SHAHRYAR KAVOUSSI: Yes. So for prevention, um, it's interesting because the same group that published a study recently in nature, they're going to be looking at metformin, which is a medication that people take for diabetes or polycystic ovary syndrome, because it does actually increase GDF 15 levels in non-pregnant people and for pregnant women. So that medication, if studies show it to be safe in certain doses, they increase those levels for desensitization and actually desensitize the female patient before she's pregnant. That could potentially help. That's not proven. And it's not something that's done as standard of care yet, it's going to be studied. There's also the idea of giving GDF, like during pre-pregnancy, to help with sensitization. There's a phase one clinical trial to show safety, but we just need more data on that. We need to see efficacy and safety in phase two and phase three trials before that's used. And this idea of blocking GDF during the pregnancy actually, maybe blocking GDF 15 with some kind of medication, which is during pregnancy. And we all get a little nervous about giving medications that are new during pregnancy. So there's still a lot of research to be done before there's some treatment modalities for this GDF.

REBECCA THOMAS: All right. We are out of time. Dr. Kavoussi with St. David's South Austin Medical Center. Thank you so much for sharing your time and your expertise with us tonight.

DR. SHAHRYAR KAVOUSSI: Thank you, Rebecca. Appreciate you. Thank you.