Baby knows best: Fetuses emit hormone crucial to preventing preeclampsia

In a study using mice, researchers from the University of North Carolina at Chapel Hill found that a hormone, adrenomedullin, plays a crucial role in preventing the pregnancy complication preeclampsia. Surprisingly, this hormone protects women from preeclampsia when emitted by the fetus, not the mother, during the most critical times in pregnancy.

“We’ve identified the fact that the baby is important in protecting the mom from preeclampsia,” said the study’s senior author, Kathleen M. Caron, Ph.D., Assistant Dean for Research at the UNC School of Medicine and an associate professor in the Department of Cell Biology and Physiology. “If the baby’s cells are not secreting this hormone, the mother’s blood vessels don’t undergo the dilation that they should.”

Preeclampsia affects roughly one in fifteen pregnancies. An important characteristic of the condition is that blood vessels in the placenta fail to enlarge, or dilate, to accommodate increased blood flow to the fetus. Untreated, it can threaten the life of both mother and baby.

“We really don’t know that a pregnant woman is going to get preeclampsia until she has it,” said Caron. Because the condition has numerous risk factors and causes, it’s difficult for doctors to know which patients are at highest risk. “Identifying molecules that could predict preeclampsia would be really important.”

The researchers studied mice that were genetically programmed to produce either reduced or increased levels of adrenomedullin. The study revealed that in a normal pregnancy, the fetus secretes adrenomedullin into the placenta during the second trimester, signaling special cells called “natural killer cells” to help dilate the mother’s blood vessels and allow more blood to flow to the growing fetus.

The study is one of the first to identify an important chemical message sent from fetus to mother in the womb. Scientists understand more about the mom’s side of the ‘chemical conversation’ that goes on between mother and baby, but much of the hormonal signaling in the placenta remains a mystery.

Preventing Preeclampsia
Preeclampsia in pregnancy is thought by many to be largely preventable with good nutrition. Hard to believe? It’s true: For healthy women without any underlying medical conditions, preeclampsia- also known as toxemia of pregnancy -  can in most cases be prevented. How empowering is that?

Ideally, you should begin with a highly nutritious preconception and pregnancy diet several months or more prior to conception. The earlier the better! Because although the symptoms of preeclampsia don’t show up until later in pregnancy, the syndrome is thought to begin in the first trimester with the implantation of the placenta.

Here’s what you should be sure to include in your balanced pregnancy diet to prevent preeclampsia in pregnancy:

  Plenty of fish and good fats: One theory of what causes preeclampsia points to the burden of building the large human brain, which is 60% fat. Don’t be afraid to load up on low mercury fish and traditional fats like real butter, coconut oil, olive oil and small amounts of minimally processed seed oils like flax, sesame and sunflower.

  Eat at least 75 grams of protein daily: According to the Brewer diet, this is the most important thing you can do to prevent preeclampsia in pregnancy.

  Salt your food to taste: This is another main component of the Brewer pregnancy diet. While swelling can be caused by too much salt, it can also result from inadequate salt intake. If you are eating a whole foods diet, the latter is more likely and you should be sure salt your food to taste with a natural salt source. (I recommend Celtic sea salt.)

  Get your vitamin D: A new study has shown vitamin D deficiency to be a risk factor in developing preeclampsia in pregnancy. Most Americans have less than optimal levels of vitamin D and it may be helpful to get a vitamin D test to check your levels.

By identifying the key role of adrenomedullin, the research could pave the way to new methods for detecting and preventing preeclampsia. For example, adrenomedullin levels could potentially be used as a biomarker, or early indicator, to identify which patients might be predisposed to the condition. “Having a biomarker would be wonderful—it could allow the physician to manage a woman differently in the early part of her pregnancy,” said Caron.

As a next step, the researchers plan to build upon their mouse studies to examine patterns of adrenomedullin levels and preeclampsia in pregnant women.


This paper was published online ahead of print on May 1, 2013 in the Journal of Clinical Investigation (JCI). The paper will appear in the June 2013 print edition.

The study’s co-authors include Manyu Li, Nicole M.J. Schwerbrock, Patricia M. Lenhart, Kimberly L. Fritz-Six, Mahita Kadmiel, Kathleen S. Christine, Scott T. Espenschied, Helen H. Willcockson and Christopher P. Mack of UNC and Daniel M. Kraus of Duke University Medical Center.


Tom Hughes
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University of North Carolina Health Care

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