Why pregnant women are advised not to eat liver

Between acceptance and suspicion, most women during pregnancy are wary of eating liver to avoid a potential risk that might harm the fetus and themselves, even if small. So what raised doubts about liver during pregnancy?

Liver, whether from chicken, beef or goat, contains vitamin A in its active form that the body can readily absorb, known as “preformed vitamin A.” Other animal sources that contain it include cheeses, milk, butter, egg yolk, fish oil and cod liver oil.

If a pregnant woman’s vitamin A level becomes elevated, it is associated with a possibility of fetal malformations or even miscarriage. Vitamin A is converted in body tissues into one of its active unstable forms known as retinoic acid, which is necessary during fetal development, but retinoic acid levels in blood serum must remain very low to preserve normal fetal growth, especially in the first trimester.

If retinoic acid levels rise greatly in the pregnant mother, it can pass through the placenta to the fetus and trigger gene activity during a very sensitive stage of organ and tissue formation, which may lead to structural or functional malformations. These can include hydrocephalus, incomplete development of the skull and brain, spina bifida, eye abnormalities, small ears, underdeveloped jaws, cleft palate and others, according to laboratory experiments on animals that explored the effects of vitamin A excess on the fetus published in the 1980s.

Because liver is rich in vitamin A, it is among the foods women try to avoid to protect their children from defects that could last a lifetime. Therefore, continuous, repeated or large-quantity consumption of liver during pregnancy is not recommended.

Effects of vitamin A deficiency in the mother and fetus

Vitamin A is one of the essential vitamins the body needs for many vital functions. But how do you balance its importance with advising a pregnant woman to avoid all its sources during fetal development, while her body also urgently needs nutrition? How does the body compensate for a deficiency that may sometimes be severe?

Notwithstanding recommendations to avoid it and its listed harms, vitamin A plays an important role for both mother and fetus. It is necessary for the development and differentiation of the fetal eye’s cells, contributes to bone growth, has protective roles for the skin and mucous membranes, strengthens the immune system, and helps improve the functional capacity of the reproductive organs.

For the pregnant woman, vitamin A is necessary to maintain night vision and to continuously supply the fetus with what it needs for the development of organs that require it. Low vitamin A levels are common among pregnant women, especially in the last trimester when fetal growth accelerates and maternal blood volume increases. According to World Health Organization statistics published in 2009—based on work previously conducted by Professor West Keith and published in 2002—about 20 million pregnant women worldwide are at risk of low vitamin A levels, of whom 7 million actually suffer from a clear deficiency.

Low vitamin A rates are concentrated among pregnant women in developing countries, specifically in Africa and in Southeast and South Asia. The danger of deficiency lies in the increased incidence of a condition known as night blindness (difficulty seeing at night or in dim light). According to the same WHO report, night blindness affects 9.8 million pregnant women among those at risk of low vitamin A levels.

Correcting vitamin A deficiency in pregnancy

If one of the factors in the spread of low vitamin A levels during pregnancy is mothers’ low educational level, authorities should ensure women are educated about the importance of vitamin A for them and their fetuses and guide them to obtain it from safe sources and in amounts within the recommendations adopted by specialists. They should neither avoid it completely nor consume it excessively without medical supervision.

Specialists and experts recommend that pregnant women meet their vitamin A needs through dietary sources and avoid vitamin A supplements, except in certain cases, to prevent risks that could lead to fetal malformations.

The recommended amount of vitamin A in cases of severe deficiency is the equivalent of 800 micrograms of retinol per day, which is difficult to obtain from food alone.

The daily recommended amount of vitamin A for pregnant women aged 19–50 is estimated at 770 micrograms, and a pregnant woman’s need for vitamin A increases by about 50 micrograms per day during the last three months of pregnancy.

Are vitamin A supplements banned during pregnancy?

Specialists generally recommend avoiding vitamin A supplements during pregnancy to protect mother and fetus. However, in some cases specific doses of certain vitamin A formulations may be recommended to correct severe deficiency and prevent night blindness, on the condition that liver is completely avoided while taking supplements or that a liver product is eaten at most once. This guidance was reported by Van den Berg and Holshof Deslibier from the Netherlands in 1996 after they studied 58 pregnant women.

Daily vitamin A intake should not exceed 10,000 international units (IU) or 25,000 IU per week, and it is preferable for a pregnant woman to take vitamin A in the form of beta-carotene, which the body converts into vitamin A and is considered safe during pregnancy and does not cause fetal malformations.

Leafy green vegetables (spinach and others), yellow vegetables (pumpkin and carrot) and orange non-citrus fruits (mango, apricot and papaya) are rich in provitamin A carotenoids.

It is always advised to consult a specialist to monitor the health of the mother and fetus and to make the best decision about taking vitamin A supplements. Pregnant women should avoid regular consumption of liver rich in vitamin A, especially when taking vitamin A supplements, as doctors advise, to prevent fetal toxicity or malformation.