Page Banner

United States Department of Agriculture

Agricultural Research Service

Related Topics

 Vitamin D in Pregnancy Study



Who is conducting this study?

Charles B. Stephensen, PhD from the USDA, ARS, Western Human Nutrition Research Center and Bryon Jacoby, MD from the UC Davis Medical Center Division of Obstetrics & Gynecology are conducting this study. The study has been reviewed and approved by the UC Davis Committee for the Protection of Human Studies. There is only minimal health risk associated with participation in this study.         


What is the purpose of the study?

The purpose of this study is to measure the effects of vitamin D supplementation during pregnancy on maternal and newborn health. We are doing this study to determine if additional vitamin D supplementation is beneficial in pregnant women who may be at risk for vitamin D deficiency.


Who can participate?

Pregnant women who:

••        are receiving prenatal care

••        are over 18 years of age

••        are less than 20 weeks pregnant

••        have low sun exposure and low dietary intake of vitamin D (this will be determined from a questionnaire)


Who is not eligible to participate?

Pregnant women:

••        with a disease that affects kidney function or bone metabolism

••        using anti-hypertension or anti-inflammatory medications

••        with a diagnosis of type 1 or type 2 diabetes

••        who cannot take nutritional supplements

••        who are more than 60 pounds overweight


What do I need to do to participate?

You will complete an oral informed consent and a screening questionnaire by telephone to determine if you are eligible to participate. If you are eligible and you decide to participate, the first study visit will be scheduled at the WHNRC. You will give your written informed consent to participate in the study. We will record your age, weight and height, blood pressure, heart rate and body temperature. We will collect a small blood sample, 20 mL (4 teaspoons), which will be used to measure vitamin D status and immune function.


In addition to being given a prenatal multivitamin and mineral, you will be randomly assigned to one of the two study groups: either 400 International Units (IU) or 2,000 IU of vitamin D per day. Neither you nor the study personnel will know in which group you are placed. You must agree to stop taking all other dietary supplements during the study.


The second study visit will be scheduled when you are 26-28 weeks pregnant, and the third visit at 34-36 weeks pregnant. At both times, we will record your weight and height, blood pressure, heart rate and body temperature. We will collect 20 mL of blood at each visit. Each study visit will take approximately 1 hour.


After you have delivered your baby, you will return any remaining study supplements to the study team.


What are the benefits to you from this study?

You will receive prenatal vitamins.


Will I receive compensation?

You will receive compensation up to $100 for completion of the study.


What should I do if I have questions?

Call (530) 754-7781 and press #2





Return to Nutrition Studies


Last Modified: 8/13/2016
Footer Content Back to Top of Page