A recent study published by the Journal of Pregnancy evaluated the knowledge and practices of obstetricians regarding vitamin D testing and supplementation for their patients during pregnancy.
Vitamin D deficiency has been linked with a variety of health complications during pregnancy, including but not limited to preterm birth, preeclampsia, low birth weight and developmental delays. Yet, the prevalence of low vitamin D status among pregnant and breastfeeding mothers remains high. In fact, one study found that nearly 70% of pregnant women have insufficient vitamin D levels in the United States. Additionally, research has shown that this number is even higher in other regions, with an alarming 93.5% of pregnant women vitamin D deficient in Northern India.
Much debate continues to exist among health experts regarding the ideal reference range for vitamin D status and the correct dosage of vitamin D supplementation to produce healthy levels during pregnancy and breastfeeding. The primary US agencies that weigh in on the matter, the Food & Nutrition Board, the Endocrine Society and the Vitamin D Council, disagree on these topics. According to the Food & Nutrition Board, vitamin D sufficiency is reached at levels > 20 ng/ml (50 nmol/l); whereas, the Endocrine Society states that sufficiency occurs at levels > 32 ng/ml (80 nmol/l) and the Vitamin D Council believes that optimal levels begin at 40 ng/ml (100 nmol/l) as our ancestors maintained.
This debate has created a sense of uncertainty among health care professionals when treating their patients. So the question remains, what is the ideal reference range for vitamin D status among pregnant women, and how do we obtain that level? Our species evolved with an abundance of sun exposure. Our hunter and gatherer ancestors maintained levels around 40 – 50 ng/ml (nmol/l) solely from the sun. However, in today’s society, the population tends to be unable or unwilling to expose themselves to the sun without the use of sunscreen, which blocks the synthesis of vitamin D. This has contributed to a significant decrease in vitamin D levels, resulting in vitamin D deficiency throughout the world.
New research continues to support that vitamin D supplementation doses beyond what is recommended by the Food & Nutrition Board improves pregnancy outcome. In fact, research conducted by Drs. Hollis and Wagner at the Medical University of South Carolina (MUSC) discovered that daily supplementation with 4,000 IU during pregnancy was required to reduce pregnancy and birth complications. Furthermore, they found that 6,400 IU taken on a daily basis while breastfeeding provided the infants with sufficient vitamin D status.
Further analysis of the Hollis and Wagner study data by GrassrootsHealth indicated that reaching a vitamin D serum level of at least 40 ng/ml significantly improved birth outcomes (vs looking at the data based on supplement intake), especially with preterm birth. GrassrootsHealth is working with the Medical Univeristy of South Carolina (MUSC) to implement vitamin D screening and supplementation requirements at their hospital, and are leading the nation in putting the research into practice.
Obstetricians and gynecologists are required to make medical decisions in this environment of uncertainty based off of the evidence they are presented with. Therefore, researchers recently aimed to determine the current knowledge and practices of obstetricians regarding vitamin D screening and supplementation during pregnancy.
The researchers provided a survey to 225 randomly selected obstetrician and gynecologist Fellows and Junior Fellows of the American College of Obstetricians and Gynecologists (ACOG) from Collaborative Ambulatory Care Network (CARN). These fellows came from across the US and the District of Columbia and agreed to participate in ACOG research studies yearly. Of this group, 101 (45%) completed the questionnaire and thus were included in the study.
The survey focused on physician practice patterns for vitamin D education, supplementation and testing in pregnant women. Here is what the researchers found:
- Less than half (45%) of the obstetricans had read the information provided by ACOG regarding vitamin D during pregnancy, and those who had were more likely to screen their pregnant patients than those who hadn’t (36.9% vs 17%, respectively; p < 0.01).
- A total of 68.3% of obstetricans stated that vitamin D insufficiency was a problem in their patient population, with 66.3% of physicians indicating that their patients would benefit from supplementation.
- Only 16.8% of obstetricians recommend vitamin D supplementation in addition to their prenatal supplements to all their patients; whereas 52.5% would recommend supplementation to some of their patients.
- A total of 25.8% of obstetricans routinely tested their pregnant patient’s vitamin D levels.
- Those who viewed vitamin D status as an issue among their patients were more likely to test their vitamin D levels (32.8% vs 9.7%; p = 0.002) and recommend supplementation (91.2% vs. 16.1%; p = 0.001).
- Approximately 82% of the obstetricians consider vitamin D supplementation during pregnancy a safe practice.
- The most common vitamin D supplementation dose recommended to a pregnant patient was 1,000 IU/d (41.6%), 400 IU/d (22.8%) and 600 IU IU/d (20.8%), respectfully.
- Recommending vitamin D supplementation over 1,000 IU/day for pregnant women was highly unlikely [(1,200 IU/day (5%), 2,000 IU/day (3%) and 4,000 IU/day (2%)].
The researchers concluded,
“Opinion regarding supplementation levels and indicators of adequacy were split between the two competing recommendations, suggesting that clinical practice will likely remain variable across physicians, with uncertain public health consequences.”
Despite the abundance of research supporting the role of vitamin D in both maternal and infant health, these results suggest that a disconnect exists between the latest research findings and medical practice. Despite the fact that the Endocrine Society and Vitamin D Council views pregnant and breastfeeding women as a population in need of vitamin D testing and supplementation, the lack of consensus between vitamin D researchers and regulatory authorities is reflected in medical practice.
The researchers stated,
“Ongoing clinical trials may provide the needed guidance, but until more definitive results are achieved, clinical practice in the US will likely remain variable across physicians, with uncertain public health consequences.”
Sturges, M. & Cannel, JJ. Do obstetricians routinely provide vitamin D screening and supplementation for their pregnant patients? The Vitamin D Council Blog & Newsletter, 2016.
Mohamed, S., Al-Hendy, A., Schulkin, J. & Power, M. Opinions and Practice of US-Based Obstetrician-Gynecologists regarding Vitamin D Screening and Supplementation of Pregnant Women. Journal of Pregnancy, 2016.