Study finds five-fold increase in risk of preeclampsia; results offer more evidence that the US RDA is too low
by Craig Weatherby
Many fans of the television show “ER”—especially women—will recall an emotionally draining first-season episode (“Love’s Labor Lost”) in which a pregnant women died from preeclampsia.
The pregnant character succumbed despite desperate medical efforts, because, as in real life, preeclampsia can be difficult to diagnose.
This past summer, the Los Angeles Times published an article about doctors who write for medical shows, and noted that a decade later, the fears raised by this early “ER” episode still resonate.
As the episode’s co-writer—pediatrician Lisa Zwerling, MD—said to The Times, “When I told my ob/gyn I wrote for 'ER’, he said, ‘Do you know you've made an entire generation of women paranoid about preeclampsia’” (McNamara M 2007)?
Paranoia is an overreaction, but concern about preeclampsia among pregnant women is not unreasonable.
Preeclampsia occurs in about eight percent of first pregnancies, and it’s the leading cause of premature delivery and maternal and fetal illness and death worldwide, killing more than 75,000 women and newborns annually.
The condition is usually signaled by high blood pressure, edema (swelling) in hand and feet, and headaches.
The greatest risks are run by women experiencing their first pregnancy, older mothers, African-American mothers, women who’ve undergone many pregnancies, and women with a past history of diabetes, high blood pressure, or kidney disease.
The exact cause of preeclampsia remains unknown, but the results of a new data analysis link low vitamin D levels to a five-fold increase in risk of the dangerous condition. And they show that women getting the US RDA from supplements still aren't getting enough, from sun exposure or foods.
Low vitamin D levels common in pregnancy and linked to preeclampsia risk
It’s becoming clear that vitamin D ranks among the most important—but neglected—nutrients. Scientific reports published in the past several years indicate that the average blood levels in America are too low.
As a result Americans run increased risks of osteoporosis, fractures, common cancers, autoimmune diseases, influenza, and cardiovascular problems. (See the accompanying report in this issue, “More Vitamin D = Less Breast and Colon Cancer.”)
Earlier this year, a report from the University of Pittsburgh determined that this common deficiency extends to pregnant women (Bodnar LM et al February, 2007). This is what the authors found:
Now, a report by the same Pittsburgh team
- “At delivery, vitamin D deficiency and insufficiency occurred in 29.2% and 54.1% of black women and 45.6% and 46.8% black neonates [newborns], respectively.”
- “Five percent and 42.1% of white women and 9.7% and 56.4% of white neonates were vitamin D deficient and insufficient, respectively.”
- These results suggest that black and white pregnant women and neonates residing in the northern US are at high risk of vitamin D insufficiency, even when mothers are compliant with [recommendations for] pre-natal vitamins.
- Fish Fit the Vitamin D Bill; Sockeye Salmon Stand OutCertain fish rank among the very few substantial food sources of vitamin D.
- Among fish, wild sockeye salmon may be the richest source of all, with a single 3.5 ounce serving surpassing the US RDA of 400 IU by about 70 percent: Vitamin D per 3.5 ounce serving*Sockeye salmon 687 IUAlbacore tuna 544 IUSilver salmon 430 IUKing salmon 236 IUSardines 222 IUSablefish 169 IUHalibut 162 IU *For our full test results, click here.
- Higher-dose [vitamin D] supplementation is needed to improve maternal and neonatal vitamin D nutriture.”
—led by assistant professor Lisa Bodnar, PhD, MPH, RD
vitamin D levels as a probable promoter of preeclampsia (Bodnar LM et al May, 2007).
The University of Pittsburgh group analyzed health records and blood samples from women and newborns treated at the University’s Magee-Women's Hospital and affiliated obstetricians’ private practices. The records covered the period between 1997 and 2001.
The health data came from the records of 1,198 women enrolled in the Pregnancy Exposures and Preeclampsia Prevention Study, designed to detect factors that may predispose women to preeclampsia. And they took a closer look at 55 women who developed preeclampsia and 220 healthy controls within this group.
Blood samples were taken from women just before their 22nd week of pregnancy and again just before delivery. Umbilical cord blood samples were taken from newborns and tested for vitamin D levels.
The results were striking:
This increased risk related to vitamin D status remained evident even after the researchers accounted for known risk factors such as race, ethnicity and pre-pregnancy body weight.
- Low vitamin D levels early in pregnancy were associated with a five-fold increase in the odds of preeclampsia.
- The risk was doubled by even small declines in vitamin D levels.
And the authors reported a surprising finding that highlights the need to raise Americans’ vitamin D levels: “Also troubling was the fact that many of the women reported taking prenatal vitamins, which typically contain 200 to 400 International Units of vitamin D” (Bodnar LM et al May, 2007).
They drew the obvious conclusions: “Maternal vitamin D deficiency may be an independent risk factor for preeclampsia. Vitamin D supplementation in early pregnancy should be explored for preventing preeclampsia and promoting neonatal well-being.”
- Bodnar LM, Catov JM, Simhan HN, Holick MF, Powers RW, Roberts JM. Maternal vitamin d deficiency increases the risk of preeclampsia. J Clin Endocrinol Metab. 2007 Sep;92(9):3517-22. Epub 2007 May 29.
- Bodnar LM, Simhan HN, Powers RW, Frank MP, Cooperstein E, Roberts JM. High prevalence of vitamin D insufficiency in black and white pregnant women residing in the northern United States and their neonates. J Nutr. 2007 Feb;137(2):447-52.
- McNamara M. The Specialists. Los Angeles Times, July 29, 2007. Accessed online September 10, 2007 at http://www.latimes.com/features/printedition/magazine/la-tm-tvdocs25jul29,0,5860716.story?coll=la-headlines-magazine