Is vitamin A (Vitamin A) still considered teratogenic during pregnancy?

From the Guidelines

Vitamin A is still considered teratogenic during pregnancy when consumed in excessive amounts, particularly in the retinol form, and pregnant women should restrict their intake to 5000-10,000 IU/d to minimize the risk of birth defects. According to the most recent evidence, high-dose vitamin A supplements can cause birth defects affecting the baby's skull, face, heart, brain, and nervous system 1. The recommended dietary allowance (RDA) of vitamin A during pregnancy is safe and necessary, which is 770 mcg (2,565 IU) daily. Prenatal vitamins typically contain appropriate amounts. Women should be particularly cautious with retinoid forms of vitamin A (like retinol, retinyl palmitate) found in some skin products and supplements, as these pose higher risks than beta-carotene (found in fruits and vegetables) 1.

Some key points to consider:

• Pregnant women should avoid high-dose vitamin A supplements (over 10,000 IU or 3,000 mcg daily)
• The beta-carotene form of vitamin A is preferred over retinol, especially during the first trimester
• Prenatal vitamins typically contain appropriate amounts of vitamin A
• Women who have had bariatric surgery may be at risk of vitamin A deficiency and should be monitored closely by a specialist dietitian

It is essential for pregnant women to consume vitamin A through a balanced diet and prenatal vitamins, but avoid additional supplements unless prescribed by their healthcare provider 1. The teratogenic effects of excess vitamin A occur because it interferes with normal cell differentiation and migration during early fetal development, particularly affecting neural crest cells.

From the Research

Vitamin A Teratogenicity

• The teratogenicity of vitamin A is a complex issue, with some studies suggesting that high doses of vitamin A may be teratogenic, while others indicate that moderate doses are safe 2, 3, 4.
• A study published in the International Journal for Vitamin and Nutrition Research found that daily oral vitamin A supplements of 4000,10,000, and 30,000 IU given for 3 weeks were in the range or slightly above the range of endogenous plasma levels seen in early pregnancy, and were considered non-teratogenic 2.
• Another study published in Reproductive Toxicology found that doses of 10,000 IU/d or less of preformed vitamin A were considered safe, while doses greater than 10,000 IU/d as supplements had been reported to cause malformations in a single epidemiologic study 3.
• A study published in the American Journal of Obstetrics and Gynecology found no association between periconceptional vitamin A exposure at doses greater than 8000 IU or greater than 10,000 IU per day and malformations in general, cranial neural crest defects, or neural tube defects 4.
• However, a study published in The New England Journal of Medicine found that high dietary intake of preformed vitamin A appears to be teratogenic, with an apparent threshold near 10,000 IU per day of supplemental vitamin A 5.
• A more recent study published in Cureus found that vitamin A in high doses has been found to be highly teratogenic, leading to severe fetal abnormalities if exposure occurs during pregnancy 6.

William's Obstetrics (26th edition)

• According to the provided information, there is no direct reference to William's Obstetrics (26th edition) in the given studies.
• However, based on the available evidence, it can be inferred that vitamin A is still considered teratogenic in high doses, but the exact threshold for teratogenicity is not well established 2, 3, 4, 5, 6.