Objective: Metabolic study on plasmatic levels of homocysteine (Hcy) in healthy women during normal or pathological pregnancy accompanied with coresponding levels of Hcy in amniotic fluid and foetal sera. Increased levels of Hcy - hyperhomocysteinaemia is respected as an independent risk factor accelerating the early development of vessel damage and causing the neural tube defects (NTD). Design: Basic study to get our own data about Hcy in Czech healthy and population at risk of pregnant and non-pregnant women. Setting: Department of Obstetrics and Gynaecology, 1st Faculty of Medicine, Charles University, Prague. Methods: Total homocysteine in plasma, amniotic fluid and foetal sera was estimated by chroma- tographic method with use of fluorescence detection. Results: Normal homocysteine in preclimacteric healthy nonpregnant women is: 9.7 ± 1.6 mmol/l with evident age-dependence. In healthy climacteric women are higher levels of Hcy (correspon- ding to the men values): 11.8 ± 2,6 mmol/l. After use of hormonal contraceptives the plasmatic levels of Hcy decrease: 7.2 ± 2.0 mmol/l. In physiological pregnancies Hcy reachs the lowest values: 4.4 ± 1.7 mmol/l with any evident oscillations during pregnancy. In women in childbed period was Hcy 8.4 ± 2.1 mmol/l observed. In pathological pregnanciesare its levels slightly elevated: 6.3 ± 2.1 mmol/l, most evident in placental abruptions: 7.5 ± 1.7 mmol/l. In pregnant women with susp. results of screening on M. Down only unsignificant increase of Hcy was observed: 6.12 ± 2.4 mmol/l. In amnial fluids of healthy pregnant women are levels of Hcy are quite low: 4.1 ± 1.2 mmol/l with any oscillations during pregnancy. In foetal sera of pregnancies at risk (NTD, susp., trisomy, inborn errors of metabolism): 3.6 ± 1.4 mmol/l of Hcy was detected. The foetoplacental quotient for Hcy is 0.62. Conclusion: Average values for Hcy were established in physiological as well as in pathological pregnancies and till now only limited diagnostic significance has been observed. The hyperhomo- cysteinaemia mentioned in previous papers was not in NTD observed because our pregnant patients were regularly supplemented with all critical vitamins (folate, B6 , B12 ).

        Key words: homocysteine, homocysteinaemia, hyperhomocysteinaemia, folate embryopathy, risk pregnancy, neural tube defects