FOLATE METABOLISM IMPAIRMENT IN SMOKING PREGNANT WOMEN

Abstract

Tobacco smoking is one of the pressing issues of public health. Russia ranks among the countries with a very high smoking rate. Smoking frequency among pregnant women in St. Petersburg is about 26.4%, among which 18.9% of the women smoke every day, and the rest 7.5% of them on the occasion. Complications from pregnancy (threatening miscarriage, premature delivery, anaemia) and from labour and delivery (labour abnormalities) in the smoking women occurs at almost twice the rate in those non-smoking, threatening miscarriage and anaemia notably having a more severe clinical picture and being more reluctant to the therapy. Smoking is one of the risk factors of hyperhomocysteinemia, which is in turn a marker of the folate metabolism impairment in the organism. It has been shown that homocysteine plasma level increases in the smoking pregnant women. Besides, a significant decrease in folate plasma level has been found in the same women. It is a folate deficiency that most of all raises homocysteine level in blood plasma. It has been proved that elevated homocysteine level has a direct toxic effect on the endothelium. Microthrombosis and microcirculation loss result in a series of obstetric complications. In late pregnancy, hyperhomocysteinemia causes chronic fetoplacental insufficiency and chronic intrauterine hypoxia. Therefore, many complications from pregnancy, such as gestosis and fetoplacental insufficiency, are associated with hyperhomocysteinemia, which is most probably caused by the smoking derived folate metabolism impairment. Supplementary folate and vitamin B complex therapy may possibly improve the pregnancy and delivery outcome in the pregnant women with high homocysteine plasma level. This, however, requires supportive clinical trials. Smoking cessation at birth spacing and prevention of hyperhomocysteinemia must be an essential condition for favourable prognosis for pregnancy.