Vitamin A during pregnancy

Cohlan, S. Q., Congenital anomalies in the rat produced by excessive intake of vitamin A during pregnancy. Pediatrics, 1954, n 556-567. 

A maximum dose of 5000 lU of vitamin A during pregnancy is now reconunended by the American College of Obstetricians and Gynecologists. In addition, the diet should contain plenty of fruits and vegetables that are naturally rich in beta-carotene (see Chemistry Around Us 12.2). 

Forty healthy participants, 25 female and 15 males, aged 19-33 years with a body mass index between 18 and 24 kg/m took part in the study. Excluding criteria were smoking, current dental surgery, illness of the pharynx or the cavity of the mouth, malabsorption, long-time medication, use of a toothpaste with vitamin A during the last 2 months prior to the study, pregnancy, and metabolic diseases. 

Dudas 1, Czeizel AE. Use of 6,000 lU vitamin A during early pregnancy without teratogenic effect. Teratology 1992 45(4) 335-6. 

Therefore, pregnant women who previously used an oral contraceptive should ask their doctor whether they should take a mineral and vitamin supplement during pregnancy. 

Excessive intakes of vitamin D during pregnancy and early infancy may cause idiopathic hypercalcemia, or the hypercal-cemic syndrome, a condition characterized by narrowing of the aortic valve of the heart, a peculiar facial appearance, and mental retardation. 

The bile acid sequestrants are contraindicated in patients with known hypersensitivity to the drugs. Bile acid sequestrants are also contraindicated in those with complete biliary obstruction. These drags are used cautiously in patients with a history of liver or kidney disease Bile acid sequestrants are used cautiously during pregnancy (Pregnancy Category C) and lactation (decreased absorption of vitamins may affect the infant). 

During pregnancy, a well-balanced diet consisting of starch, fibre, vitamins and minerals is essential. Foods rich in sugar, fats and refined carbohydrates must be limited. 

Folic acid (vitamin Bg) is a conjugate of a pteridine unit, p-aminobenzoic acid, and glutamic acid. Deficiency of folic acid leads to anaemia, and it is also standard practice to provide supplementation during pregnancy to reduce the incidence of spina bifida. 

Much recent interest has been aroused by the fact that retinoid compounds, including both retinol and retinoic acid, reduce the incidence of experimentally induced cancer. In addition, 13-czs-retinoic acid taken orally is remarkably effective in treatment of severe cystic acne. s However, both vitamin A and retinoic acid in large doses are teratogenic, i.e., they cause fetal abnormalities. The use of 13-cis-retinoic acid during early phases of pregnancy led to a high incidence of major malformations in infants born.1 11 1... 

During early pregnancy, high doses of vitamin A (as found in halibut and shark liver oils) can lead to birth defects (15). Fish oil supplements rich in vitamin A should therefore be avoided by women in the first trimester and those who might become pregnant. 

The normal requirement of vitamin A for adults is supplied by an adequate diet. The rational uses of retinol are in the treatment of vitamin A deficiency and as prophylaxis in high-risk subjects during periods of increased requirement, such as infancy, pregnancy, and lactation. Once vitamin A deficiency has been diagnosed, intensive therapy should be instituted. The patient should then be maintained on a proper diet. 

During pregnancy and lactation, it is advisable to increase the maternal intake of vitamin A by about 25%. As the typical North American diet readily provides adequate intake of the vitamin, supplementation is not routinely indicated. 

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