How much vitamin D should I take while pregnant?
Many women believe that vitamin D isn’t something they need to worry about because they can easily get enough of it by spending time out in the sun. Since it comes from the sun, it must be something that you can get enough of naturally and not something that you need to take a supplement for. You might be surprised to know that up to one-third of the US population is at risk for vitamin D deficiency.
You may be at higher risk for vitamin D deficiency if fall into any of these categories:[2,3]
If you don’t get enough sun exposure, then you may think that increasing the amount of vitamin D in your diet should make up for your deficiency. However, finding vitamin D in your diet alone can be difficult. Vitamin D is only found in fortified milk, fatty fish, fish oil, beef liver, cheese, and egg yolks. Those who are at high risk for a vitamin D deficiency may want to consider vitamin D supplementation.
It is currently recommended that all women up to the age of 70 get 600IU (international units) of vitamin D per day and women older than 70 take 800 IU. If a blood test has proven that you are vitamin D deficient, you may need to take up to 4,000 IU per day of vitamin D. This will depend on what your doctor’s specific recommendations.
All pregnant and breastfeeding women should also get the recommended amount of 600 IU per day of vitamin D. There is some evidence that shows pregnant women may need doses as high as 1000 IU per day to maintain a healthy pregnancy. Since most prenatal vitamins have only 400 IU, this means that pregnant and breastfeeding women are likely to need an additional vitamin D supplement.
For pregnant women, getting enough vitamin D is especially important because if you don’t get enough, then your baby can’t get enough either. Babies who are deficient in vitamin D can have abnormal bone development which can cause their bones to break or to be abnormally formed.
If you are pregnant or breastfeeding and have any of the high-risk factors for vitamin D deficiency, then you may need a blood test to check your vitamin D levels. There is currently no evidence to support screening all pregnant or breastfeeding women for this deficiency. Most women are unlikely to need this blood test. 
While too little vitamin D is clearly a problem, too much vitamin D isn’t great either. Experts know that doses of vitamin D up to 4,000 IU per day are safe but the safety of doses above this amount is unknown.3 If you are considering taking a vitamin D dose above this level, you should talk with your doctor before starting it.
With research constantly evolving in this area, many experts believe that these recommendations are likely to change. Don’t be surprised if you see new recommendations for vitamin D in the next few years.
 LeBlanc ES, Zakher B, Daeges M, Pappas M, Chou R. Screening for Vitamin D Deficiency: A Systematic Review for the U.S. Preventive Services Task Force. Ann Intern Med. 2015;162(2):109-122.
 ACOG Committee on Obstetric Practice. ACOG Committee Opinion No. 495: Vitamin D: Screening and Supplementation During Pregnancy. Obstet Gynecol. 2011 Jul;118(1):197-8.
National Institutes of Health Office of Dietary Supplements. Vitamin D: Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/. Updated February 11, 2016. Accessed April 19, 2017.
 The National Academies (US). Dietary reference intakes for calcium and vitamin D. Washington, DC: National Academy Press; 2010.
 Wagner CL, Greer FR. Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. American Academy of Pediatrics Section on Breastfeeding; American Academy of Pediatrics Committee on Nutrition [published erratum appears in Pediatrics 2009;123:197]. Pediatrics. 2008;122:1142–52.