Pregnancy

Why take vitamin D during pregnancy and breastfeeding?

Pregnancy is a condition that exposes you to vitamin D deficiency and, according to the FIMP (Italian Federation of Doctors and Pediatricians), all pregnant women should take a supplement of 600 IU/day. In women with risk factors for vitamin D deficiency, dosages should be higher, equal to 1,000-2,000 IU/day.

The main source of vitamin D (80-90%) is exposure to UVB solar radiation. The diet provides about 10-20% of the requirement.

What is the role of vitamin D?

The main function of the vitamin is to promote the reabsorption of calcium in the kidneys, the intestinal absorption of phosphorus and calcium and the bone mineralization processes.
Vitamin D also performs numerous functions unrelated to bone structure, thereby influencing various physiological processes.

What is the daily requirement of Vitamin D?

The daily requirement of this vitamin varies according to gender and age and is higher in children in the first year of life, pregnant and breastfeeding women and the elderly.

In our work we have the opportunity to read the blood tests of several women of childbearing age and one of the often deficient or very deficient values ​​is that relating to Vitamin D.

Vitamin D status is assessed by measuring levels of the hepatic metabolite 25-(OH)-D in the blood and expressing its concentration in nanograms per milliliter (ng/ml).

From the dosage of this metabolite you can have these conditions:

  • Deficiency: Values ​​below 20 ng/ml
  • Insufficiency: Values ​​between 20 and 30 ng/ml
  • Normality: Values ​​between 30 and 100 ng/ml
  • Toxicity : Values ​​higher than 100 ng/ml

What are the conditions that increase the demand for Vitamin D?

  • Living in places where sunlight is lacking.
  • Pregnancy and breastfeeding.
  • Obesity
  • Old age.
  • Have dark skin.
  • Spending a lot of time indoors or wearing heavy clothing.

How Much Vitamin D Should I Take During Pregnancy?

Pregnancy is a condition that exposes you to vitamin D deficiency and, according to the FIMP (Italian Federation of Doctors and Pediatricians) , all pregnant women should take a supplement of 600 IU/day. In women with risk factors for vitamin D deficiency, dosages should be higher, equal to 1,000-2,000 IU/day.

How long ? From the beginning of pregnancy, throughout pregnancy and breastfeeding.
Without this supplement, there is a risk that your child will have brittle bones which can lead to rickets (disease affecting bone development in children).

Some women are more likely to need vitamin D than others. The risk of being vitamin D deficient increases if:

  • High skin pigmentation
  • Reduced exposure to sunlight
  • Obesity
  • Malabsorption
  • Adolescence
  • Previous child with rickets
  • Taking drugs that interfere with vitamin D metabolism
  • Increased risk of preeclampsia

How long in the sun?

The amount of time you need to spend in the sun to make enough vitamin D is different for everyone and depends on your skin type, time of day, and time of year.

It is not necessary to sunbathe in the literal sense, that is, to get a tan.

15 minutes a day in the sun, two or three times a week, exposing only your arms and face should be enough.

What foods contain vitamin D?

Vitamin D-rich foods include eggs, oily fish (such as salmon and sardines). Some breakfast cereals and yogurts are also fortified with vitamin D.

As always, keep in mind that some foods should be avoided in pregnancy. For example, liver is rich in vitamin D, but you shouldn’t eat it during pregnancy.

It’s hard to get enough vitamin D from food alone, so the best thing to do is try to eat a healthy, balanced diet as best you can while pregnant and while breastfeeding. You can also try to exercise outdoors in the sun whenever possible and safely.

Does my child need vitamin D?

For breastfed infants (breast milk contains insufficient amounts of vitamin D for the prevention of vitamin D deficiency) from birth to 1 year of age in the absence of risk factors, it is recommended to administer vitamin D 400 IU/day . In the presence of risk factors for vitamin D deficiency, up to 1,000 IU of vitamin D can be administered.

The FIMP (Italian Federation of Pediatricians) recommends prophylaxis with vitamin D in the first year of life even for bottle-fed children. The vitamin D content of formula milk is around 400 IU/l, but an infant is only able to take a liter of formula milk a day when it reaches a weight of around 5-6 kg, therefore a few months after birth. Upon reaching this weight, bottle-fed infants often begin weaning with the concomitant reduction in the amount of formulated milk taken.

In any case, the pediatrician is the primary reference for information about vitamin D supplementation.

What effects on the newborn?

A systematic review of several recent studies published in the authoritative scientific journal Fertility and Sterility has highlighted that vitamin D supplements during pregnancy could increase the weight of newborns at birth and their length.

A team of scientists analyzed data on 2,299 newborns who participated in 13 studies. The meta-analysis found that maternal vitamin D supplementation during pregnancy was associated with small but significant increases in birth weight and length: 108 grams more weight and 0.3 cm more length .

Women taking vitamin D had a significant increase in blood 25(OH)D.

Vitamin D exists in two precursors:

  • D3: cholecalciferol, it is synthesized in the skin thanks to sun exposure starting from 7-dehydrocholesterol, vitamin D3 is also introduced with food through animal fats
  • D2: ergocalciferol: derives from ergosterol (again due to the effect of solar radiation) which comes from food.

Both D3 and D2 are transformed in the liver and kidney into 25 hydroxyvitamin D (25) D (OH) which is the inactive form, and calcitriol D (1,25 (OH) 2D) which is the biologically active form.

A vitamin D deficiency in adults is linked to osteopenia, osteoporosis, muscle and bone weakness, predisposition to tumors, autoimmune diseases, infectious diseases and cardiovascular diseases.

Vitamin D works by promoting intestinal absorption of calcium.

The researchers found no link between vitamin D and the incidence of preeclampsia, gestational diabetes, and preterm birth. The only link, evaluating the pregnancies and the newborns, was found with the increase in weight and length of the newborn, as you can see from the table below published in the study:

Fetal growth is a complex process that depends on many factors, including genetic background, placental development, nutrition, and physical activity. Therefore, vitamin D may play a minor role in fetal growth compared to other factors.

According to the researchers, it would be recommended that pregnant women take the daily dose of vitamin D of 600 IU,  given that nowadays many women around the world would not receive the minimum recommended dose of vitamin D.

Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.

Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.

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