Endothelium-derived nitric oxide synthase protein expression in ovine placental arteries.
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During the third trimester, fetoplacental and uterine blood flows increase dramatically to meet the high metabolic demands of the growing fetus. We hypothesized that the expression of endothelial nitric oxide synthase (eNOS) in fetoplacental artery endothelium and the concentrations of nitric oxide (NO) and cyclic GMP (cGMP) in amniotic fluid (AF) are increased during the third trimester of ovine gestation. Placental arteries and AF were collected from ewes at 110, 120, 130, and 142 days of gestation (n = 24; mean +/- SEM term = 145 +/- 3 days). Expression of eNOS protein was measured in intact and denuded placental arteries and in endothelium-derived protein by Western analysis and confirmed by immunohistochemistry. Concentrations of NO (nitrates plus nitrites) and cGMP were determined in AF. Placental artery eNOS protein expression was localized to the endothelium, where it was markedly greater than in vascular smooth muscle. Placental artery endothelium-derived eNOS expression and AF cGMP concentrations were similar at 110 and 120 days of gestation; however, both peaked at 130 days at levels two- to threefold above baseline (P < 0.05) before returning to baseline at 142 days of pregnancy. The AF NO (nitrates plus nitrites) levels, however, increased progressively between 120 days of gestation and term (P < 0.05). We concluded that endothelium-derived placental artery eNOS levels, AF NO (nitrates plus nitrites), and AF cGMP were markedly increased during the third trimester, thus supporting a role for NO-mediated elevations in cGMP in the control of fetoplacental blood flow. (+info)
The significance of crown-rump length measurement for predicting adverse pregnancy outcome of threatened abortion.
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OBJECTIVES: To determine if in women with threatened miscarriage the measurement of fetal crown-rump length (CRL) is a useful predictor of spontaneous miscarriage and small for gestational age (SGA) infants. METHODS: Fetal CRL was measured in 310 singleton pregnancies with live fetuses, presenting with threatened miscarriage before 13 weeks of gestation. The relationship between fetal CRL and pregnancy outcome was investigated. RESULTS: In fetuses with CRL < 18 mm there was a significant positive association between the deficit in CRL for gestation and the incidence of subsequent spontaneous miscarriage. In those cases with CRL deficit more than 2 standard deviations (SDs) the incidence of miscarriage was 13.7%, whereas if the CRL was between the mean and -2 SDs the incidence of miscarriage was 8.3%. In fetuses with CRL > or = 18 mm there was a significant positive association between the deficit in CRL for gestation and the incidence of SGA. In those cases with CRL deficit of more than 2 SD the incidence of SGA was 27.3%, whereas if the CRL was between the mean and -2 SDs the incidence of SGA was 18.9%. CONCLUSIONS: The findings of this study suggest that the measurement of fetal CRL may be a useful predictor of spontaneous miscarriage and SGA in pregnancies with threatened miscarriage. (+info)
Use of time to event analysis to estimate the normal duration of human pregnancy.
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BACKGROUND: Current estimates of the average duration of human pregnancy are flawed by inaccurate estimation of the time of conception and by failure to account adequately for the effect of routine elective delivery post-term. METHODS: In this study, 1514 healthy pregnant women were studied in whom the discrepancy between the menstrual history and first trimester crown-rump length estimated gestational age was within -1 to +1 day difference. The duration of gestation was estimated using time to event analysis: non-elective delivery was taken to be the event, and elective delivery was taken to be censoring. RESULTS: The median time to non-elective delivery using the Kaplan-Meier product limit estimate was 283 days after last menstrual period (LMP) and there was no difference comparing male and female fetuses. The median was significantly greater for nulliparous women compared with multiparous women (284 versus 282 days, P < 0.0001). Multivariate analysis using Cox's proportional hazards model confirmed the independent effect of nulliparity on duration of pregnancy [hazard ratio, 0.75; 95% confidence interval (CI) 0.67-0.85] and demonstrated no effect of maternal age, previous abortions, fetal sex, high parity, or bleeding before 24 completed weeks of gestation. Bleeding in the third trimester of pregnancy was, however, associated with an earlier onset of spontaneous labour (hazard ratio, 1.38; 95% CI 1.03-1.84). CONCLUSION: This study provides a basis for predicting the probability of labour at a given gestational age at term. (+info)
Growth promoting effects of human placental lactogen during early organogenesis: a link to insulin-like growth factors.
(20/203)
Many maternally derived factors may be involved in the regulation of embryonic growth but the control mechanisms involved are poorly understood. Human placental lactogen (hPL) has been implicated in playing a role in the control of embryonic growth. Several investigators suggested that there may be a possible link between the effects of this hormone and insulin-like growth factors (IGFs). In order to determine the growth promoting potential of hPL and involvement of IGFs in the mechanism of action of the hormone, 9.5 d rat embryos were cultured in vitro for 48 h in depleted serum in the presence and absence of hPL with additional IGF antisera. The growth supporting capacity of the serum was reduced by removal of low molecular weight molecules by prolonged filtration of the serum using filters with a molecular weight exclusion of 30 kDa. Addition of hPL (3.2-25.6 ng/ml) to depleted serum significantly improved embryonic growth and development, suggesting that the developing embryo may utilise hPL. The presence of antisera against hPL, IGF-I and -II abolished the hPL-induced increase in the development in all parameters suggesting that there may be a possible link between the IGFs and the effects of hPL on rat embryonic development and this hormone may achieve its growth promoting effects via IGFs. (+info)
Screening for Down syndrome using first-trimester ultrasound and second-trimester maternal serum markers in a low-risk population: a prospective longitudinal study.
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OBJECTIVES: To compare nuchal translucency and second-trimester maternal serum measurements as alternative methods of antenatal screening for Down syndrome in a low-risk population and to evaluate the consequence of combining the results in the estimation of risk. DESIGN: In a consecutive series of 4130 women aged less than 38 years with a singleton pregnancy, we examined both the detection rate of Down syndrome by nuchal translucency measurement at 10-14 weeks and maternal serum screening by human chorionic gonadotrophin and alpha-fetoprotein at 14-18 weeks. Women with a nuchal translucency measurement of > or = 3 mm and women with a maternal serum screening-derived risk > or = 1/250 were recommended to have amniocentesis. A second-trimester detailed ultrasound scan was also performed in all women. The outcome of all pregnancies was recorded prospectively and the detection rate and false-positive rate of different screening strategies were retrospectively analyzed. RESULTS: Out of the 4130 pregnancies that were followed (mean maternal age, 30.1 years), 12 cases of Down syndrome were observed (0.28%), all detected prenatally. Seven of 12 cases had a nuchal translucency measurement of > or = 3 mm (58%), and six out of 10 cases with available maternal serum screening had a calculated risk of > or = 1/250 (60%). Four of the five Down syndrome cases with a nuchal translucency measurement of < 3 mm were detected by subsequent maternal serum screening. At a threshold giving 5% of positive tests, the sensitivity of nuchal translucency, maternal serum screening and combined risk screening were 75%, 60% and 90%, respectively. CONCLUSIONS: In screening for Down syndrome, an approach which combines the results from first-trimester nuchal translucency and second-trimester biochemistry is effective and increases the detection rate compared to the use of any single test. However, this strategy is likely to raise the false-positive rate and the interpretation of maternal serum screening-derived risk should be combined with the first-trimester nuchal translucency measurement. (+info)
Three-dimensional sonographic volumetry of the placenta and the fetus between weeks 15 and 17 of gestation.
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OBJECTIVES: Three-dimensional sonographic volume measurement enables for the first time direct comparison of the increase in size of different but closely interacting structures like the placenta and fetus. Our aim was to calculate the fetal and placental volumes between weeks 15 and 17 of gestation, to monitor the difference in the increase of the fetal and placental sizes and to determine their mutual relationship. METHODS: Fetal and placental sonographic volume measurements were made in 356 singleton pregnancies. To measure the relationship between fetal and placental volumes, a quotient was calculated. Regression analyses were performed to analyze the dependence of the fetal and placental volumes and placental quotient on the week of gestation and other influencing variables. RESULTS: The mean of the fetal volume increased markedly from 67.8 to 76.6 mL (by 13%) within the 3 weeks of observation, whereas placental volume increased only slightly (111.1 to 114 mL (by 2.6%)). The random variation of placental volumes around the mean in all three gestational weeks was considerably higher than that of fetal volumes, indicating that in this early period of gestation there is little correlation between fetal and placental sizes. Fetal volume correlated better to gestational week than did placental volume. CONCLUSION: The quotient of fetal and placental volume might assist in the diagnosis of high-risk pregnancies and the assessment of a normal or large fetus with a small placenta. (+info)
Crown-rump lengths in missed miscarriages and trisomy 21.
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OBJECTIVES: To compare crown-rump lengths with karyotypes of missed miscarried fetuses and to determine a relationship between crown-rump length and trisomy 21. STUDY DESIGN: Chorionic villus sampling was performed on 129 consecutive missed miscarriages between 10 and 12 weeks by last menstrual period in patients >or= 35 years of age. Crown-rump length was correlated with the karyotype. Statistical analysis was performed using Student's t-test. RESULTS: Twenty-one of 129 missed miscarriages involved fetuses affected by trisomy 21. The crown-rump length was < 22 mm in 77% of missed miscarriages. Using a crown-rump length of >or= 22 mm for the prediction of trisomy 21 had a sensitivity of 86%, specificity of 89%, positive predictive value of 60% and negative predictive value of 97%. At 10-12 weeks, the crown-rump lengths of missed miscarried fetuses with trisomy 21 was significantly larger (P or= 35 years of age, with a missed miscarriage, in whom pregnancies reached >or= 10 weeks from the last menstrual period, a fetal crown-rump length of >or= 22 mm has a high probability that the etiology of the loss will be secondary to trisomy 21. (+info)
The effects of maternal and fetal parameters on the quality of nuchal translucency measurement.
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OBJECTIVE: To evaluate the influence of maternal and fetal parameters on the quality of fetal nuchal translucency measurement. DESIGN: This was a prospective study in 227 consecutive pregnant women undergoing nuchal translucency screening by transabdominal sonography. The same well-qualified sonographer performed all the scans and in each case the best-quality image was selected and scored according to an image scoring system (total maximum score, 9). The quality of the image was examined in relation to maternal age, weight, abdominal wall thickness, amniotic sac diameter, posterior uterine wall depth (distance between abdominal wall surface and posterior uterine wall surface), placental location, fetal crown-rump length and nuchal translucency thickness. Correlation coefficients were calculated and stepwise linear regression was used to adjust for confounders and to define the predictors for image score. RESULTS: The only two parameters that provided a significant independent contribution to the prediction of the image score were posterior uterine wall depth and fetal crown-rump length. Intravariable analysis of these two parameters demonstrated that the cut-off associated with a significant change in the image quality was 80 mm for posterior uterine wall depth (score difference, 1.06; P < 0.001) and 70 mm for crown-rump length (score difference, 0.77; P = 0.001). In the group of women with two values above these cut-off points, an average score decrease of 1.90 (P < 0.001) was observed. CONCLUSIONS: The quality of fetal nuchal translucency measurement is poorer when the fetal crown-rump length is > 70 mm and the posterior uterine wall depth is > 80 mm. (+info)