Written by Tatjana Djakovic, Staff Writer. This study demonstrates that women with vitamin D levels > 40 ng/mL had significantly lower risk of preterm births compared to those with vitamin D levels < 20ug/mL.
Pre-term birth (PTB) is a leading cause of infant death world-wide and the United States has one of the highest rates of PTB compared to other developed countries 1. In addition, racial differences in PTB rates in the United States account for highest rates of PTB occurring among African Americans (18%), followed by Hispanics (12%) and 11% among whites 2.
Multiple population-based studies have found an association between low vitamin D levels and a higher risk of PTB 3,4. Given the high rate of PTB nationwide and using data from randomized controlled trials that demonstrate a risk reduction with vitamin D supplementation, the Medical University of South Carolina implemented a new standard of care for pregnant women to receive vitamin D testing and supplementation. The goal of this recent study is too see if the data can be replicated in a large diverse population of pregnant women 5.
Researchers examined the medical records of 1,046 pregnant women, aged 18-45 years, who received a 25(OH)D test and delivered an infant between September 2015 and December 2016. Patients were educated on the importance of vitamin D and received a free bottle of vitamin D supplements (5000 IU per capsule) at first visit and a personalized dosing recommendation based on results of their first vitamin D test (5).
The researchers found a significant inverse association between vitamin D levels and the risk of PTB. Women with a 25(OH)D concentration of >40ng/mL had a 60% lower risk of PTB compared to those with a 25(OH)D concentration of <20 ng/mL (p<0.0001). After adjusting for socioeconomic variables, this lower risk remained (p = 0.002).
Similar decreases in PTB risk were observed for the following PTB subtypes:
- Spontaneous PTB: For those with 25(OH)D concentrations >40 ng/mL compared to those with 25(OH)D concentrations <20 ng/mL, there was a 58% lower risk of spontaneous PTB (p = 0.02)
- PTB by race/ethnicity: There were significant decreases in PTB risk for >_40 ng/mL vs. <20 ng/mL for both white (65%, p=0.03) and non-white (68%, p = 0.008), and among women with a prior history of PTB (80%, p = 0.02).
Limitations of the study were that two thirds (63%) of women had only one 25(OH)D test done during pregnancy which did not allow for a trimester evaluation and a more complete vitamin D analysis of the vitamin D benefits for those who had low initial levels.
However, the study results did show that higher vitamin D status is significantly associated with lower PTB risk for both PTB subtypes and that adequate vitamin D plays an important role in reducing the underlying causes of PTB which include maternal hypertension, pre-existing diabetes, and non-reassuring fetal status. Improving the vitamin D status of women with these underlying conditions may prevent the need for a medically indicated preterm delivery. Vitamin D supplementation is inexpensive: inadequate vitamin D intake is a modifiable risk factor that can be addressed during the prenatal period to decrease the disparity in PTB rates between race/ethnic groups and ultimately decrease morbidity, mortality and economic costs.
Source: McDonnell, Sharon L., Keith A. Baggerly, Carole A. Baggerly, Jennifer L. Aliano, Christine B. French, Leo L. Baggerly, Myla D. Ebeling et al. “Maternal 25 (OH) D concentrations≥ 40 ng/mL associated with 60% lower preterm birth risk among general obstetrical patients at an urban medical center.” PloS one 12, no. 7 (2017): e0180483.
© 2017 McDonnell et al. Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Posted August 24, 2017.
Tatjana Djakovic, MS, graduated from Roosevelt College in 2011, with concentration in biochemistry. Her research was in determining antioxidants and macronutrients in herbal teas. She is originally from Gospic, Croatia and currently resides in Carol Stream, IL.
References:
- Blencowe H, Cousens S, Oestergaard MZ, et al. National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications. The Lancet. 2012;379(9832):2162-2172.
- Hamilton BE MJ, Osterman M, Curtin SC, Mathews TJ. Births: Final Data for 2014. Vol 642015.
- Bodnar LM, Platt RW, Simhan HN. Early-pregnancy vitamin D deficiency and risk of preterm birth subtypes. Obstetrics and gynecology. 2015;125(2):439.
- Miliku K, Vinkhuyzen A, Blanken LM, et al. Maternal vitamin D concentrations during pregnancy, fetal growth patterns, and risks of adverse birth outcomes. The American journal of clinical nutrition. 2016;103(6):1514-1522.
- McDonnell SL, Baggerly KA, Baggerly CA, et al. Maternal 25 (OH) D concentrations≥ 40 ng/mL associated with 60% lower preterm birth risk among general obstetrical patients at an urban medical center. PloS one. 2017;12(7):e0180483.
