Vitamin D Deficiency in Pregnant Women

Vitamin D is a fat-soluble vitamin that functions like a hormone in the body, playing an essential role in calcium absorption, bone health, and immune system regulation. During pregnancy, the demand for vitamin D increases as the developing baby requires calcium for bone formation, which depends on adequate maternal vitamin D levels.

Despite India's tropical climate and abundant sunshine, vitamin D deficiency is surprisingly prevalent among Indian women, including those living in coastal cities like Visakhapatnam. Studies indicate that 70-90% of Indian women have insufficient vitamin D levels. This paradox is attributed to cultural practices such as limited sun exposure, use of sunscreen, indoor lifestyles, and skin pigmentation that reduces vitamin D synthesis from sunlight.

Vitamin D deficiency during pregnancy is defined as a serum 25-hydroxyvitamin D level below 20 ng/mL, with insufficiency ranging between 20-30 ng/mL. Routine screening may not be standard everywhere, so it is important to discuss testing with your healthcare provider, especially if you have risk factors for deficiency.

The primary source of vitamin D is synthesis in the skin upon exposure to ultraviolet B (UVB) sunlight. Women who spend most of their time indoors, cover most of their skin when outdoors, or consistently use high-SPF sunscreen may not produce enough vitamin D. Air pollution in urban areas can also filter out UVB rays, further reducing skin synthesis.

Dietary intake of vitamin D is challenging because few foods are naturally rich in this nutrient. Fatty fish, egg yolks, and fortified dairy products provide some vitamin D, but vegetarian diets, which are common in many Indian households, often lack these sources. Fortified foods are not as widely available in India as they are in Western countries, adding to the difficulty of meeting daily requirements through diet alone.

Certain medical conditions, including obesity, kidney disease, and malabsorption disorders, can affect vitamin D metabolism and storage. Women with darker skin tones require more sun exposure to produce the same amount of vitamin D as those with lighter skin. Previous pregnancies with closely spaced intervals can also deplete vitamin D stores.

Vitamin D deficiency often goes undetected because its symptoms are nonspecific and develop gradually. Common complaints include bone and muscle pain, generalised fatigue, and a feeling of heaviness in the limbs. Some women may experience frequent muscle cramps, particularly in the legs, which are easily dismissed as normal pregnancy discomfort.

More pronounced deficiency may lead to frequent infections due to impaired immune function, mood changes including low mood or irritability, and difficulty concentrating. In severe cases, bone softening (osteomalacia) can occur, causing deep bone pain and weakness. Since these symptoms overlap with common pregnancy experiences, a blood test is the most reliable way to confirm vitamin D status.

For the mother, vitamin D deficiency has been associated with an increased risk of gestational diabetes, preeclampsia, and the need for caesarean delivery. Low vitamin D levels may also contribute to postpartum depression, though research in this area is ongoing. Maintaining adequate levels supports maternal bone health at a time when calcium demands are high.

For the baby, maternal vitamin D deficiency can affect skeletal development, potentially leading to low birth weight, poor bone mineralisation, and in severe cases, neonatal rickets. Some studies suggest that adequate maternal vitamin D may support healthy lung development and immune system maturation in the newborn. Children born to mothers with sufficient vitamin D levels may have better bone density and lower risk of certain childhood conditions.

The long-term implications of prenatal vitamin D deficiency are still being studied, but the existing evidence strongly supports ensuring adequate levels throughout pregnancy for the well-being of both mother and child.

Safe sun exposure is the most effective way to boost vitamin D levels. Aim for 15-20 minutes of direct sunlight on your arms and face during the morning hours (before 10 AM) several times a week. In Visakhapatnam, the coastal climate provides ample opportunity for morning walks along the beach or in parks, which can help maintain vitamin D levels naturally while also providing gentle exercise.

Dietary sources of vitamin D include fatty fish such as salmon, sardines, and mackerel. Egg yolks, fortified milk, fortified orange juice, and certain mushrooms exposed to UV light also contain meaningful amounts. For vegetarian women, fortified plant milks, fortified cereals, and mushrooms can help, though these sources alone may not be sufficient to meet pregnancy requirements.

Supplementation is often necessary, particularly for women with confirmed deficiency. Your healthcare provider may recommend cholecalciferol (vitamin D3) supplements in doses appropriate for your current levels. Standard prenatal vitamins typically contain 400-600 IU of vitamin D, but higher therapeutic doses may be prescribed for women with documented deficiency. Always follow your doctor's guidance on dosage.

Request a vitamin D blood test (25-hydroxyvitamin D) during your first prenatal visit, especially if you have risk factors such as limited sun exposure, a vegetarian diet, darker skin, or a history of vitamin D deficiency. Many hospitals and diagnostic centres in Visakhapatnam offer this test as part of extended prenatal panels.

Consult your doctor if you experience persistent bone pain, muscle weakness, frequent infections, or mood disturbances that seem disproportionate to your pregnancy stage. Your provider can interpret your test results in the context of your overall health and prescribe the appropriate supplementation regimen. Avoid taking high-dose vitamin D supplements without medical supervision, as excessive vitamin D can lead to harmful calcium buildup in the blood.