Increased fetal DNA in the maternal circulation in early pregnancy is associated with an increased risk of preeclampsia

OBJECTIVE: The aim of our study was to determine if fetal DNA is present in the maternal circulation in early pregnancy before the clinical manifestation of preeclampsia, and if this could be predictive of the development of preeclampsia. STUDY DESIGN: Blood were obtained from patients attending for a first antenatal visit. Cases were asymptomatic women who subsequently developed preeclampsia matched to control women for parity and gestational age. Real-time polymerase chain reaction (PCR) using TaqMan primers and probes directed against SRY gene sequences quantified fetal DNA in the maternal circulation. RESULTS: There were 88 cases of women with preeclampsia and 176 control women, both sampled at a mean gestation (+/-SD) of 15.7 +/- 3.6 weeks. The presence of fetal DNA in the maternal circulation in early pregnancy is associated with an 8-fold increased risk of developing preeclampsia. CONCLUSION: Increased fetal DNA is present in the maternal circulation in early pregnancy in women who subsequently develop pre-eclampsia and there appears to be a graded response between the quantity of fetal DNA and the risk of developing pre-eclampsia.     

Detection of fetal Rhesus D gene in whole blood of women booking for routine antenatal care

OBJECTIVE: To determine if the RhD status of the fetus can be detected in an unselected group of RhD-negative women with ongoing pregnancies booking for routine antenatal care. MATERIAL AND METHODS: We obtained 2.5 ml of whole blood from 202 unselected women with a normal ongoing pregnancy who booked for antenatal care before 20 weeks' gestation. DNA was extracted and real time quantitative PCR performed. Primers and a specific probe were targeted at the Rhesus D gene. RESULTS: Of 194 women, 31 were RhD-negative with no evidence of prior isoimmunisation. They delivered 17 RhD-positive and 14 RhD-negative babies. Of the 17 RhD-negative women carrying a RhD-positive fetus, the RhD gene was detected in the maternal blood in 14 (82%). There were no false positives. The quantity of RhD gene detected in the maternal blood of RhD-negative mothers ranged from 2 x 10(2) to 4 x 10(6) copies/ml of whole blood. CONCLUSION: Using real time quantitative PCR assays to amplify free fetal DNA in the maternal circulation, identification of RhD-positive fetuses in RhD-negative mothers is feasible when they book for antenatal care. Before such RhD genotyping can be introduced into clinical practice, however, further studies are required to show that false negative results can be eliminated and to show that this diagnostic test is reliable outside a research setting.     

Non-invasive fetal RhD typing and RhD negative pregnant women--preliminary observations

OBJECTIVES: For a follow up of a pregnancy in a RhD neg women it is crucial to learn whether her fetus is RhD pos or neg. AIM: Detection of fetal RHD gene in the plasma of RhD neg mother in various periods of pregnancy and a comparison with RhD of a newborn. 45 plasma samples from various periods of pregnancy from 28 RhD neg women. MATERIAL AND METHODS: Examination of: RHD (exon 7 and 10), SRY, GSTM1 and ACE using real-time PCR. RESULTS: Fetal RHD was detected in all 23 mothers with RhD pos child; in one of them, in the 12th week of gestation, RHD was detected only using primers for exon 7, however in the 21st--the presence of both RHD exons was confirmed. Five mothers delivered RhD neg newborns--both RHD exons were not detected. In all 5 cases other fetal genes were examined to be certain that the fetal DNA was analysed. In all 3 mothers who delivered RhD neg boys, the SRY was detected. Among 2 mothers who delivered RhD neg girls, the presence of fetal DNA was confirmed in one, by GSTM1 detection. CONCLUSIONS: 1) Real-time PCR is an appropriate, non-invasive method for fetal RhD examination. 2) Two RHD exons should be examined. 3) Control genes should be investigated and found to be sure that negative result of the RHD was not false negative due to the lack of fetal DNA; SRY is an appropriate control for boys, while for girls further investigations are needed, which are in progress.     

Use of maternal plasma for noninvasive determination of fetal RhD status

Determination of the fetal RhD typing using free fetal DNA in maternal plasma is beginning to enjoy widespread acceptance in Europe. Case 1, the partner of an RhD-sensitized patient, was identified with a heterozygous paternal phenotype by serologic testing. Maternal plasma was drawn at 18 weeks' gestation to determine the fetal RhD status. The result was unable to be reported as RhD negative; the patient subsequently underwent amniocentesis to confirm an RhD-negative fetus. Case 2, a partner of another RhD-sensitized patient, was similarly identified with a heterozygous paternal phenotype by serologic testing. Maternal plasma was also drawn at 18 weeks' gestation to determine the fetal RhD status. It returned RhD negative and allowed for the avoidance of invasive testing for the remainder of the pregnancy. Therefore, maternal plasma testing for fetal RhD status represents a new tool in the management of the cases of RhD alloimmunization in pregnancy.     

Methylenetetrahydrofolate reductase 677 C-->T polymorphism and plasma folate in relation to pre-eclampsia risk among Peruvian women.

OBJECTIVES: Pre-eclampsia is an important cause of maternal and fetal morbidity and mortality worldwide. Hyperhomocyst(e)inemia in pregnancy is associated with an increased risk of pre-eclampsia in most studies. Nutritional and genetic factors regulate homocyst(e)ine levels. A missense mutation 677 C-->T in the gene for methylenetetrahydrofolate reductase (MTHFR) has been associated with an increased pre-eclampsia risk in some, although not most, previously studied populations. METHODS: To further understand the role of this polymorphism in the etiology of pre-eclampsia, we genotyped a total of 125 pre-eclamptics and 179 normotensive pregnant Peruvian women. RESULTS: The wild-type allele frequency among cases and controls was 54% and 58%, respectively. Twenty percent of cases and 17% of controls were homozygous for the 677 C-->T MTHFR genotype (T/T). After adjustment for confounding by covariates including maternal age, nulliparity, pre-pregnancy body mass index and use of prenatal vitamins, women homozygous for the 677 C-->T MTHFR genotype (T/T) experienced a modest, statistically non-significant increased risk of pre-eclampsia (adjusted OR 1.6, 95% CI 0.7, 3.8). Maternal folate deficiency was associated with a statistically non-significant doubling in risk of pre-eclampsia in this population (adjusted OR 2.0, 95% CI 0.9, 4.3). CONCLUSIONS: There was no evidence to suggest that pre-eclampsia risk is positively associated with the T/T genotype overall, or in the context of folate deficiency.     

Noninvasive determination of fetal RhD status using fetal DNA in maternal serum and PCR

OBJECTIVE: Because prenatal testing of fetal RhD status by amniocentesis carries small yet finite risks to the fetus and mother, this study sought to determine whether fetal DNA in maternal serum could be used to detect fetal RhD status by polymerase chain reaction (PCR). METHODS: A retrospective analysis was made of frozen serum specimens from 20 sensitized RhD-negative pregnant women (ranging from 15.0 to 36.0 weeks' gestation) who were confirmed by serology at birth to have been carrying RhD-positive fetuses. Eleven serum specimens from RhD-negative individuals served as controls. DNA was isolated from serum and used in two PCR-based methods to detect a 99 base pair (bp) DNA fragment specific for the RhD gene and a 113 bp fragment specific for the RhCE gene as control. RESULTS: Overall, in 14 (70%) of 20 RhD-positive fetuses the 99 base pair RhD-specific PCR product was detected. There was no false positive detection among the 11 control serum specimens. CONCLUSION: The results illustrate the ability to detect fetal RhD sequences in maternal serum of sensitized women. Moreover, the findings demonstrate that fetal single-gene disorders can be detected prenatally by using DNA isolated only from maternal serum.     

母血中胎儿DNA与子痫前期关系的研究

目的:探讨孕妇外周血中胎儿DNA的浓度水平与子痫前期之间的关系。方法:留取第一次常规产前检查的472例孕妇的外周血并随访。设置阴性对照后,采用实时PCR方法定量检测怀男性单胎并发展为子痫前期的17例孕妇及34例怀男性单胎正常孕妇的血浆胎儿DNA的SRY基因浓度。结果:发展为子痫前期患者的外周血浆胎儿DNA浓度明显高于正常孕妇,中位数分别为165.41copies/ml和48.75copies/ml,有显著的统计学差异(P<0.001)。结论:发展为子痫前期患者外周血中的胎儿DNA明显增高,而浓度水平与子痫前期的严重程度似乎无关。     

Quantitative analysis of intact fetal cells in maternal plasma by real-time PCR

OBJECTIVE: Fetal genetic materials in maternal circulation might be potentially used for non-invasive prenatal diagnosis (NIPD). In this study, we quantitatively analysed the intact fetal cells existing in maternal plasma, which would be a special method of NIPD. STUDY DESIGN: Eleven samples from preeclamptic patients, two samples from patients with RhD incompatibilities, and 30 samples from normal pregnancies as controls were collected. The intact cells in the plasma fraction were separated by centrifugation at high speed. The intact cell pellets were washed with PBS to remove any cell-free DNA. RESULTS: We were able to detect intact fetal cells in 3 out of 11 preeclamptic plasma samples from women carrying male fetuses, and from both plasma samples of RhD incompatibility affected pregnancies. However, intact fetal cells were not detected in all the 16 normal pregnancies with a male fetus, although cell-free fetal DNA was detected in all these cases. CONCLUSIONS: Intact fetal cells might be present in maternal plasma. However, the rarity of these cells limits their use for reliable, non-invasive prenatal diagnosis. The detection of such cells was successful in some preeclamptic and RhD incompatibility samples, not in the normal controls. Therefore, as opposed to free fetal DNA in maternal blood the use of intact fetal cells does not provide a reliable mode for NIPD.     

Evaluation of the clinical usefulness of isolation of fetal DNA from the maternal circulation

OBJECTIVE: To assess the reliability of isolating free fetal DNA from maternal usefulness. DESIGN: Fetal DNA was isolated from plasma or serum that was either collected prospectively or from archived samples collected for the purposes of second trimester screening. METHODS: Prospective samples were collected from patients undergoing prenatal diagnostic procedures (n = 24). A second group of samples from Rhesus negative women (n = 28) were assayed in which blood had originally been collected for maternal triple serum screening. DNA was extracted from all samples and assayed for the presence of the beta-globin gene, sex-determing region Y (SRY) gene and Rh gene. All DNA sample handling and extraction was carried out by a single operator, and polymerase chain reaction (PCR) was carried out using previously published PCR primers and appropriate controls. The accuracy of results was assessed relative to the karyotype in the case of the SRY gene or cord blood phenotype in the case of the Rh gene. RESULTS: The SRY PCR results were compared to fetal cell karyotypes obtained from invasive diagnostic testing, 21 out of the 24 samples were correctly 'sexed'. The RhD PCR results were compared to fetal cord blood samples at the time of delivery, and showed both false positive and false negative results. Two RhD negative babies were genotyped as RhD positive, despite repeat analysis. CONCLUSION: It is possible to isolate fetal DNA from maternal serum. It is a potentially clinically useful technique in our laboratory and can be used to detect male fetuses, and Rh negative fetuses. To be useful in clinical practice, it is necessary to safeguard against contamination at the time of sample handling, and to use the optimal range of primers available to cover the polymorphisms present within the RhD gene. Although not robust enough yet to be used with diagnostic certainty in our hands, immense improvements in technique, probes and real-time PCR equipment make this type of diagnosis a reality in the near future.     

ADAM12s in maternal serum as a potential marker of pre-eclampsia

OBJECTIVE: To examine whether maternal serum ADAM12s, a potential first- and second-trimester marker of fetal aneuploidy and fetal growth, had altered concentrations in the first or second trimester of pregnancies subsequently developing pre-eclampsia. METHODS: ADAM12s was measured by a time-resolved fluoroimmunoassay developed by PerkinElmer Life Science. Maternal serum samples from women taking part in early first-trimester aneuploidy screening in whom the pregnancy resulted in pre-eclampsia (64) were identified from a cohort of 4,390 singleton pregnancies in which uterine artery Doppler mean Pulsatility Index (PI) had been measured at 22-24 weeks. From amongst those cases delivering a normal term infant with birth weight greater than the 10th centile for gestational age 240 cases were selected as gestational age-matched controls. A second study group consisting of maternal serum taken at 22-24 weeks at the time of uterine artery Doppler in a group of 12 women developing pre-eclampsia were compared with 86 matched controls from a previously studied cohort of 24 cases and 144 controls. Serum ADAM12s concentrations were converted to multiple of the median (MoM) to take account of gestational age variation. RESULTS: First-trimester maternal serum ADAM12s levels in women who developed pre-eclampsia were reduced with a median MoM of 0.71 which was further reduced in those delivering prior to 35 weeks (0.50). At the 5th centile of normal (0.48 MoM) ADAM12s identified 27% of cases with pre-eclampsia and 47% of those with early pre-eclampsia. Combining ADAM12s with PAPP-A from a previous study only resulted in a further 1% increase in detection of all women developing pre-eclampsia. However combining ADAM12s with mean PI increased the detection rate to 66%. In the second trimester at 22-24 weeks the maternal serum ADAM12s levels were increased in those women developing pre-eclampsia compared to controls (709 vs 486 ug/L, p = 0.045). CONCLUSION: ADAM12s in addition to being a potential marker of aneuploidy may also be a marker of pre-eclampsia. Further studies are required to see if this can improve on the clinical discrimination already provided by PAPP-A in the early first trimester.     

Methylenetetrahydrofolate reductase 677 C→T polymorphism and plasma folate in relation to pre-eclampsia risk among Peruvian women

Objectives: Pre-eclampsia is an important cause of maternal and fetal morbidity and mortality worldwide. Hyperhomocyst(e)inemia in pregnancy is associated with an increased risk of pre-eclampsia in most studies. Nutritional and genetic factors regulate homocyst(e)ine levels. A missense mutation 677 C→T in the gene for methylenetetrahydrofolate reductase (MTHFR) has been associated with an increased pre-eclampsia risk in some, although not most, previously studied populations.

Methods: To further understand the role of this polymorphism in the etiology of pre-eclampsia, we genotyped a total of 125 pre-eclamptics and 179 normotensive pregnant Peruvian women.

Results: The wild-type allele frequency among cases and controls was 54% and 58%, respectively. Twenty per cent of cases and 17% of controls were homozygous for the 677 C→T MTHFR genotype (T/T). After adjustment for confounding by covariates including maternal age, nulliparity, pre-pregnancy body mass index and use of prenatal vitamins, women homozygous for the 677 C→T MTHFR genotype (T/T) experienced a modest, statistically non-significant increased risk of pre-eclampsia (adjusted OR 1.6, 95% CI 0.7, 3.8). Maternal folate deficiency was associated with a statistically non-significant doubling in risk of pre-eclampsia in this population (adjusted OR 2.0, 95% CI 0.9, 4.3).

Conclusions: There was no evidence to suggest that pre-eclampsia risk is positively associated with the T/T genotype overall, or in the context of folate deficiency.     

The effect of labour and placental separation on the shedding of syncytiotrophoblast microparticles, cell-free DNA and mRNA in normal pregnancy and pre-eclampsia

The clinical features of the maternal syndrome of pre-eclampsia can be explained by generalised maternal endothelial cell dysfunction, which is a part of a more global maternal systemic inflammatory response. There is growing evidence that these effects are associated with the shedding of cellular debris, including syncytiotrophoblast microparticles (STBM), cell-free DNA and mRNA, from the surface of the placenta (syncytiotrophoblast) into the maternal circulation. The increased shedding of this debris seen in pre-eclampsia is believed to be caused by placental ischaemia, reperfusion and oxidative stress. This study was carried out to determine whether uterine contractions during labour and subsequent placental separation lead to an acute increase in the release of placental debris into the maternal circulation. To assess the effects of labour, samples were taken from 10 normal pregnant (NP) and 10 pre-eclamptic (PE) women at varied time points. Similarly to assess the effects of placental delivery, plasma samples were taken from 10 NP and 10 PE women undergoing elective caesarean section. There was a significant increase in the shedding of STBM in pre-eclampsia which was not seen in normal pregnancy and there was a small rise in STBM levels at placental separation in both normal pregnant and pre-eclamptic women undergoing caesarean section, but the differences were not significant. However, levels of placental cell-free corticotrophin releasing hormone mRNA were significantly increased in labour in both normal pregnancy and pre-eclampsia and were still high 24 h after delivery in the pre-eclamptic women. There was no significant increase in fetal or total DNA in labour, but the overall levels of total DNA (maternal and fetal) was increased in labour in pre-eclampsia compared to normal labour. The enhanced shedding of STBM and CRH mRNA in pre-eclampsia labour may have a role in cases of postpartum worsening of pre-eclampsia.     

Trophoblast deportation in pre-eclamptic pregnancy.

OBJECTIVES--To examine the deportation of trophoblast cells into the maternal blood in pre-eclamptic (gestational proteinuric hypertension) and normal pregnancy. DESIGN--The monoclonal anti-cytokeratin antibody JMB2 was used in the APAAP technique to label trophoblast cells in cell smears of uterine vein blood obtained at caesarean section. SUBJECTS--10 women with proteinuric pre-eclampsia requiring caesarean section, 10 pregnant women requiring elective caesarean section for reasons other than pre-eclampsia and five control women who had never been pregnant. RESULTS--Three populations of trophoblast cells were identified; two mononuclear cytotrophoblast types with diameters varying from 11-14 microns and 19-25 microns respectively, and multinucleated syncytiotrophoblast cells varying in size from 23-88 microns. Women with pre-eclampsia had more trophoblast cells in uterine vein blood than were found in pregnant women without pre-eclampsia. There was no correlation between the numbers of trophoblast cells and the stage of gestation or severity of the pre-eclampsia, although an acute maternal or fetal event necessitating delivery was associated with increased deportation of trophoblast. Mononuclear cytotrophoblast cells were detected in the peripheral blood of only 1 of 5 pre-eclamptic patients, despite their presence in the uterine vein blood of all 5 women. CONCLUSIONS--Trophoblast deportation is increased in pre-eclamptic pregnancy, with both cytotrophoblast and syncytiotrophoblast present in the uterine vein blood, but there is no correlation with the severity of the disease. In some cases cytotrophoblast may also enter the peripheral circulation.     

Maternal and fetal serum nitric oxide (NO) concentrations in normal pregnancy, pre-eclampsia and eclampsia.

OBJECTIVES: To measure the maternal and fetal serum concentrations of total nitrites and nitrates (as an index of nitric oxide production) in normal pregnancy, pre-eclampsia and eclampsia. DESIGN: Three groups of women were studied cross-sectionally: late pregnant women with pre-eclampsia and eclampsia (n=31); normal late pregnant women (n=32); and age-matched healthy non-pregnant women (n=21). Venous blood samples were collected from all women and both maternal and umbilical venous samples were collected from pregnant women. METHODS: Blood samples were assayed for nitric oxide (NO) production by Greiss reaction which measures the combined oxidation products of NO (total nitrites and nitrates). RESULTS: There was a significant increase in serum total nitrites and nitrates concentrations in normal pregnant women than in the serum of age-matched normal non-pregnant women (P<0.0001). Significantly higher total nitrites and nitrates levels were found in the maternal sera of the pre-eclamptic and eclamptic women compared with those of normal pregnant women (P<0.0001). Also, fetal blood levels of total nitrites and nitrates were significantly increased in pre-eclampsia and eclampsia compared with those of normal pregnancy (P<0.0001). CONCLUSIONS: (1) Serum nitric oxide (NO) production is increased in normal pregnancy than in the normal non-pregnancy. (2) Maternal and fetal serum NO levels are increased significantly in pre-eclampsia and eclampsia, which possibly represents a compensatory/protective mechanism to maintain blood flow and limit platelets aggregation in the fetal-maternal circulations. (3) The increase in NO production is directly related to the severity of pre-eclampsia; this would be of diagnostic significance for the prediction of the severity of this syndrome.     

Circulating fetal and total cell-free DNA,and sHLA-G in black South African women with gestational hypertension and pre-eclampsia

Objective: Quantification of circulating fetal and total cell-free DNA (cfDNA) and soluble human leucocyte antigen (HLAG) in gestational hypertension and pre-eclampsia.

Methods: Serum cfDNA were quantified in controls, pre-eclamptics, and gestational hypertensive patients using real-time qPCR. Soluble HLAG was measured by enzyme-linked immune-sorbent assay.

Results: Serum fetal and total cfDNA levels were higher in pre-eclampsia compared with the controls and gestational hypertensives (p < 0.001), more so in severe compared with mild-to-moderate pre-eclampsia (p < 0.05). Soluble HLAG levels were lower in pre-eclamptics than controls and gestational hypertension (p < 0.05).

Conclusion: Circulating fetal and total cfDNA were increased, while soluble HLAG was decreased in pre-eclampsia.     

The genetic predisposition to produce high levels of TGF-beta1 impacts on the severity of eclampsia/pre-eclampsia

OBJECTIVES: To investigate the hypothesis that women who are genetically programmed to produce higher levels of transforming growth factor-beta 1 are more likely to develop severe eclampsia/pre-eclampsia. DESIGN: Case-control study. METHODS: Blood samples from women whose pregnancy was complicated by eclampsia (n=37) or pre-eclampsia (n=49) and healthy controls (n=86) were analyzed for the presence of polymorphisms at codons 10 and 25 of the transforming growth factor-beta 1 gene. The polymorphisms are thought to determine whether an individual produces low, medium, or high levels of the cytokine. The analysis was carried out using the ARMS-PCR technique. RESULTS: Women who developed eclampsia/pre-eclampsia with severe renal and neurological complications or had neonatal deaths/still births were more likely to have the high-producer allele T in codon 10 of the transforming growth factor-beta 1 gene than healthy controls. By contrast, the transforming growth factor-beta 1 producer genotype and allele frequency as determined by gene polymorphisms at codon 25 were comparable in cases and controls. The cytokine producer status per se appears to had no bearing on whether a patient developed eclampsia/pre-eclampsia. CONCLUSIONS: Our findings suggest that women who experience eclampsia/pre-eclampsia with severe maternal and/or fetal complications are more likely to have a genetic predisposition to produce high levels of transforming growth factor-beta 1 as defined by polymorphisms at codon 10. While it is recognized that eclampsia/pre-eclampsia has heterogenous pathomechanisms, we have demonstrated a strong relationship between poor maternal and pregnancy outcomes and codon 10 polymorphisms. The characterization of the immunogenetic make-up of the women may be an additional tool in the differentiation of component pathologies and/or prediction of severity of the syndrome.     

Alterations of maternal and fetal leptin concentrations in hypertensive disorders of pregnancy

OBJECTIVES: To investigate whether hypertensive disorders of pregnancy alter the maternal and fetal leptin levels. METHODS: Fifty primigravidas between 28 and 34 weeks of gestation were divided into three groups: group A consisted of 17 normal pregnant women with a mean gestational age of 31 weeks, group B consisted of 15 women with gestational hypertension without proteinuria with a mean gestational age of 30 weeks and group C consisted of 18 pre-eclamptic women with a mean gestational age of 31 weeks. RESULTS: The pre-eclamptics had significantly higher serum leptin levels than those in normal pregnancies (p<0.001) but no difference was noted between normal and gestational hypertensive pregnancies. Pre-eclamptic women had significantly higher umbilical vein leptin levels (4.68+/-1.66ng/ml) compared to normal pregnancies (1.92+/-0.71ng/ml) and those with gestational hypertension (2.47+/-0.81ng/ml). CONCLUSIONS: Pre-eclampsia is associated with an increase in maternal plasma leptin levels and fetal of leptin production increases in gestational hypertension and even more in pre-eclampsia.     

Reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women

OBJECTIVES: The objective of this study was to establish a reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women. This test is needed for future prenatal Rh prophylaxis. METHODS: A novel real-time PCR-based assay targeting RHD exon 7 combined with a published assay for RHD exon 10 were used to determine the fetal RHD status in DNA extracted from plasma, sampled from 56 pregnant RhD negative women in 15th-36th week of gestation. Thirty-eight samples were from ongoing pregnancies of Danish women and 21 samples from 18 pregnant women were stored anonymized samples from the International Blood Group Reference Laboratory, Bristol, United Kingdom. Prediction of fetal RhD type was compared with the serological result obtained after birth. RESULTS: The prediction of the fetal RhD type was in 100% concordance with the serological RhD type from the 16th week of gestation. One sample from the 15th week of gestation was inconclusive. The number of copies of fetal RHD DNA was found to increase with gestational age. Low levels of DNA were found to follow the Poisson distribution (p = 1.0000). CONCLUSION: Our set-up was very reliable for determination of fetal RhD genotype, and thus will be of value in prenatal Rh prophylaxis and in the management of immunized women.     

Apoptotic and morphological features of the umbilical artery endothelium in mild and severe pre-eclampsia

BACKGROUND: The pathology of the umbilical arterial endothelium in normal pregnancy and in pregnancy complicated with pre-eclampsia remains unclear. In this study the changes that occur in the umbilical artery endothelial cells were examined and endothelial cell morphology and apoptosis were compared among control, mild, and severe pre-eclamptic subjects. METHODS: Umbilical cords with a gestational age of between 35 and 40 weeks were collected from women with normal pregnancies (n=17), mild pre-eclampsia (n=10), and severe pre-eclampsia (n=12). We studied the umbilical artery endothelial cells using flow cytometry, and light and electron microscopy. Apoptosis was measured using flow cytometry and the terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling technique. The Kruskall-Wallis variance analysis and Mann-Whitney U-tests as post hoc were applied. RESULTS: In mild pre-eclamptics, the endothelial cells appeared ultrastructurally separated. A dilated endoplasmic reticulum, swollen mitochondria, and vanished mitochondrial cristae were observed. In severe pre-eclamptics, the cells were disorganized, highly contracted and vacuolated, separated from each other, and protruding prominently into the lumen. The percentages of endothelial cells that underwent apoptosis in mild (p<0.017) and severe pre-eclamptics (p<0.017) were higher than those in the controls. These apoptosis values were highest in severe pre-eclamptics (p<0.0001). CONCLUSION: Apoptosis and structural disruptions in the arterial endothelium of severe pre-eclamptics were prominent in all subjects. Increased endothelial apoptosis and structural disruptions are clinically related to intensity of pre-eclampsia, and may be associated with adaptation of the endothelial cells to pre-eclampsia.