Why Should Pregnant Women Monitor Their Vitamin D Levels?

Young pregnant woman taking medicine

Vitamin D is crucial in overall health, and for pregnant women, having an adequate level of this vitamin helps in the growth and development of the baby.

Insufficient levels during this time can lead to health issues like bone deformities, rickets, low birth weight, and gestational diabetes.

Vitamin D sources

Here are several sources of vitamin D for pregnant women and infants.

Sunlight exposure

Sunlight is the most significant source of vitamin D. When your skin is exposed to ultraviolet (UV) B radiation from sunlight, it converts 7-dehydrocholesterol to pre-vitamin D3, which is then further processed to active vitamin D3 in the body.

Food sources

You can obtain vitamin D from certain foods like:

  • Fatty fish like salmon and mackerel
  • Beef liver
  • Egg yolks
  • Fortified foods
    • Milk
    • Yogurt
    • Orange juice


Supplements are available as an alternative for those who don’t consume sufficient vitamin D from natural sources.

  • For pregnant women: Take prenatal vitamins, which generally contain a recommended intake of at least 400 International Units (IU) of vitamin D per day.
  • For infants: Take vitamin D in the form of drops or chewable tablets, and the dosage should be determined based on the age and weight of the infant.

Functions of Vitamin D

Here are some of the roles that vitamin D plays in your body.

1.     Regulation of calcium levels

Vitamin D helps in regulating calcium levels in the body, which is essential for maintaining healthy bones.

For pregnant women and infants, this increased calcium absorption supports fetal and early childhood development.

2.     Immune system function

When it comes to boosting your immune system, this vitamin helps in:

  • Activating immune cells
  • Reducing inflammation
  • Boosting immune response
  • Increasing your body’s defense against infections

3.     Potential protection against diseases

Research suggests that vitamin D may protect against certain types of cancer, cardiovascular disease and autoimmune disorders.

4.     Gene expression and cellular growth

Vitamin D interacts with receptors in the body and influences the expression of over 200 genes.

This affects bodily processes, such as:

  • Muscle function
  • Nervous system development
  • Insulin production
  • Hormone regulation, including reproductive hormones like testosterone and estrogen

5.     Pregnancy and infant development

Proper supplementation during pregnancy can reduce the risk of complications like gestational diabetes and preeclampsia, while promoting optimal fetal development.

In infants, vitamin D supplementation is essential for preventing rickets, a condition characterized by weak bones and poor growth.

fingers holding vitamin d capsule

Vitamin D in pregnancy

Why is vitamin D important for pregnant women?

When you’re pregnant, you’re more vulnerable to deficiency due to metabolic changes and limited sun exposure.

Monitoring your vitamin D levels enables early identification and intervention, including:

  • Adjusting your diet
  • Taking supplements
  • Having more sun exposure

If you don’t take enough vitamin D, complications and risks might occur, such as:

  • Skeletal malformation in the fetus
  • Impaired growth in the fetus
  • Risk of preeclampsia
  • Risk of gestational diabetes
  • Preterm birth

Factors affecting vitamin D levels

Here are the factors affecting vitamin D levels in pregnant women.


If you live in a place with lower exposure to sunlight, you might not take enough UV rays required to produce vitamin D in the body.

Skin pigmentation

Darker skin pigmentation reduces the synthesis of vitamin D in the skin because melanin competes with vitamin D for UV absorption. As a result, pregnant people with darker skin are more prone to vitamin D deficiency.

Sun exposure

Depending on your culture and personal style, these factors can limit your exposure to UV radiation:

  • Clothing coverage
  • Sun avoidance behavior
  • Sunscreen use

Maternal diet and vitamin D intake

Not taking enough vitamin D-rich foods or supplements can lead to vitamin D deficiency.


Obese women are at a higher risk of vitamin D deficiency as it gets sequestered in adipose tissue, making it less available for circulation and use in the body.

Maternal complications

Certain maternal complications may impact vitamin D metabolism and absorption. These conditions are associated with lower vitamin D levels:

  • Gestational diabetes
  • Chronic hypertension
  • Preeclampsia


Supplementation helps for monitoring and maintaining vitamin D levels in pregnant women to prevent serious health problems affecting the infant. Pregnant women at risk of deficiency need 1000 to 2000 IU daily.

Vitamin D in infants

Why is vitamin D important for infants?

In infants, vitamin D helps with the following:

  • Regulating calcium and phosphate levels for strong and healthy bones
  • Improving cognitive development
  • Strengthening immune system function

Low levels of vitamin D in infants may increase the risk of the following:

  • Autoimmune diseases
  • Allergies
  • Cancers
  • Development of rickets
  • Infections
  • Asthma
  • Cognitive disorders

Factors affecting vitamin D levels

The vitamin D levels among infants may rise or drop, depending on these factors:

  • Malabsorption syndromes: Conditions like celiac disease and cystic fibrosis can decrease the intestines’ ability to absorb and process vitamin D.
  • Liver and kidney diseases: Impaired liver or kidney function can disrupt vitamin D metabolism, leading to lower vitamin D levels in the body.
  • Mother’s breast milk quality: Breast milk alone may not provide sufficient vitamin D, especially if the mother isn’t getting enough vitamin D herself.
  • Genetic variations: Certain genetic variations that regulate vitamin D metabolism and transport can increase the risk of vitamin D deficiency.


The recommended vitamin D dose for infants is 400 IU per day.

Methods of monitoring vitamin D levels

There are different methods for assessing your vitamin D levels, such as:

  • Serum 25-hydroxyvitamin D
  • Biomarker measurements
  • Imaging techniques


Vitamin D deficiency can lead to complications such as preeclampsia, gestational diabetes, preterm birth, skeletal problems respiratory infections and asthma.

Monitoring vitamin D levels in pregnant women and infants helps prevent complications, promotes proper bone growth and reduces the risk of future health issues like allergies and autoimmune disorders.

Frequently asked questions (FAQs)

  • Why is monitoring vitamin D levels in pregnant women and infants necessary?

It’s essential to monitor vitamin D levels because low vitamin D levels during pregnancy may lead to adverse health outcomes in both the mother and child, such as gestational diabetes and preterm delivery. Low infant vitamin D levels may lead to rickets and impaired bone growth.

  • Can vitamin D levels be easily measured in pregnant women and infants?

Yes, vitamin D levels can be easily measured with a blood test. A simple heel stick test can be performed in infants to obtain a small blood sample.

  • What are the recommended vitamin D levels for pregnant women and infants?

The recommended vitamin D level for pregnant women is at least 20 ng/mL. For infants, the recommended level is at least 30 ng/mL.

  • How can pregnant women and infants get enough vitamin D?

Pregnant women can get enough vitamin D through sunlight exposure and dietary sources such as fatty fish and fortified foods. Infants can get enough vitamin D through breast milk or formula and sunlight exposure.

  • What are the risks of too much vitamin D in pregnant women and infants?

Too much vitamin D can lead to hypercalcemia, which can cause kidney damage and other health problems. Pregnant women and infants should not exceed the recommended daily dose of vitamin D.

  • How often should vitamin D levels be monitored in pregnant women and infants?

Vitamin D levels should be monitored at the beginning of pregnancy and in the third trimester. For infants, vitamin D levels should be monitored at their 1-year check-up. Additional monitoring may be necessary for individuals with certain medical conditions or those at risk for vitamin D deficiency.

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