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Biomedical subjects

M Mongelli

Publications and source records attributed to M Mongelli.

At least 37 records · Page 2Linked to original sources
PubMed1999

Fetal and maternal levels of lipid peroxides in term pregnancies.

OBJECTIVE: To examine the relationships between maternal and fetal concentrations of lipid peroxides in term pregnancies before the onset of labor. METHODS: Umbilical cord arterial and venous blood samples were collected from 114 singleton term pregnancies delivered by elective cesarean section. Base excess, oxygen, carbon dioxide and pH were measured in both samples and compared to identify double venous samples. Maternal venous and umbilical cord arterial and venous concentrations of organic hydroperoxides and malondialdehyde were assayed. RESULTS: Maternal plasma malondialdehyde was, on average, double that of cord blood, whereas maternal organic hydroperoxide was only 18% higher. Maternal organic hydroperoxide was correlated with cord arterial and venous levels of organic hydroperoxide but not with pH, carbon dioxide, oxygen or base excess. Maternal malondialdehyde concentration was significantly correlated with both umbilical arterial and venous values of malondialdehyde and with arterial oxygen. Multiple regression shows that 70% of the variation in maternal malondialdehyde can be accounted for by variation in arterial and venous malondialdehyde, and arterial oxygen and base excess. A similar regression analysis with maternal organic hydroperoxide as dependant variable incorporated only umbilical arterial organic hydroperoxide concentration. CONCLUSION: These findings suggest that there is significant trans-placental transport of malondialdehyde from the fetal circulation.

Arteries↗
PubMed1998

Screening for fetal growth restriction: a mathematical model of the effect of time interval and ultrasound error.

OBJECTIVE: We estimated the effect of ultrasound error and time interval between examinations on the false-positive rate for detecting fetal growth restriction (FGR). METHODS: Using published growth curves for the fetal abdominal circumference and a coefficient of variation for ultrasound error of 5%, computer simulation was used to estimate false-positive rates in relation to the time interval between ultrasound examinations. Growth restriction was diagnosed when there was no apparent growth in fetal abdominal circumference between two consecutive examinations. In separate studies, the false-positive rate was plotted against gestational age at the first ultrasound examination. RESULTS: There was a dramatic increase in false-positive rates as the time interval between examinations was reduced. When the initial scan was performed at 32 weeks, the false-positive rate increased from 3.2% for an interval of 4 weeks to 30.8% for an interval of 1 week. At a 2-week interval, the error was 16.9%. There was a significant increase in the false-positive rate as the gestational age at the initial ultrasound was increased. At 28 weeks, the false-positive rate with a 2-week interval was 11.8%, increasing to 24.1% at 38 weeks. By varying the coefficient of variation of the ultrasound error, the false-positive rate increased from 0.8% at an error of 2% to 31.9% at an error of 10%. CONCLUSION: Ultrasound scanning at 2-week intervals is associated with false-positive rates for growth restriction in excess of 10%, increasing to much higher rates late in the third trimester. Improved screening performance should be attainable by increasing the interval between scans and reducing measurement errors.

Anthropometry↗
PubMed1998

Analysis of birthweight and gestational age in antepartum stillbirths.

OBJECTIVE: To study the characteristics of birthweight and gestational age of third trimester fetal deaths which occurred before the onset of labour. DESIGN: Review of computerised confidential perinatal mortality records. Data originated from the 1992 Trent Region Perinatal Mortality Survey. SAMPLE: One hundred and forty-nine antepartum stillbirths of at least 24 weeks of gestation confirmed by early ultrasound scan. Congenital abnormalities and multiple pregnancies were excluded. MAIN OUTCOME MEASURES: Reported causes of stillbirth; weight-for-gestational age centiles based on a standard derived from normal pregnancies; pregnancy characteristics compared with the local maternity population. RESULTS: Of 149 stillbirths, 83 (56%) were preterm and 66 were at term, and the majority (126; 85%) occurred from 31 weeks. Most of the deaths (97; 65%) were reported as 'unexplained' even though post-mortems had been carried out in 60% of all cases. Using a gestational age-specific fetal weight standard derived from normal, term live births, 41% of all cases of stillborn infants were small-for-gestational age (< 10th centile; OR 6.2; 95% CI 3.3-11.5); 39% of which had been classified as unexplained were small for gestational age (OR 5.6; 2.6-12.0). This excess of small stillbirths was most pronounced between 31 and 33 weeks, where the weights of 63% of all stillbirths and 72% of unexplained fetal deaths were < 10th centile. Overall, a higher proportion of preterm (< 37 weeks) than term stillbirths were small for gestational age: 53% vs 26% (OR 3.3; 1.6-6.5). However, at term there were also more subtle differences in weight deficit, with more fetuses with a weight between the 10th and 50th centiles than between 50th and 90th (36 vs 11; OR 3.3; 1.4-7.8). Mothers of pregnancies ending in stillbirth were similar in age, size, parity and ethnic group to mothers of live born babies, but were more likely to be smokers (37 vs 27%, OR 1.6; 1.2-2.3). CONCLUSIONS: Many stillborn babies are small for gestational age. In the absence of significant differences in physiological pregnancy characteristics, this is unlikely to be a constitutional smallness, but represents a preponderance of intrauterine growth restriction. For a full appreciation of the strength of this association, appropriate weight standards and classifications need to be applied in perinatal mortality surveys. Many antepartum stillbirths which are currently designated as unexplained may be avoidable if slow fetal growth could be recognised as a warning sign.

Birth Weight↗
PubMed1997

The epidemiology of urinary dysfunction in Chinese women.

The epidemiology of urinary dysfunction in a Chinese population living in Hong Kong was investigated. Fifteen hundred ethnic Chinese women answered a telephone questionnaire including symptoms of urinary dysfunction, anthropometric measurements, obstetric history and place of birth. The relative predictive value of these factors was analyzed using logistic regression. The prevalence of urinary dysfunction was 13%. Ten percent reported stress incontinence, and 4% had urgency or urge incontinence. The strongest predictor was place of birth, with women born in mainland China having the highest prevalence of pure stress incontinence (OR 1.33, CI 1.1-1.6). For the symptoms of detrusor instability age was the strongest predictor, with women over 50 years being at greater risk (OR 2.8, CI 1.6-5.0). Contrary to earlier beliefs, urinary dysfunction in Chinese women is as common as in Caucasian women. Place of birth is the strongest predictor for pure stress incontinence, with women born in mainland China being at greater risk. This suggests that environmental factors in early life have a differential effect on the development of urinary incontinence.

Adult↗
PubMed1997

Birth weight, prematurity and accuracy of gestational age.

OBJECTIVE: To investigate commonly used birth weight categories in relation to gestational age assignment by menstrual (LMP) or ultrasound dates. METHODS: A total of 34,249 cases were retrieved from the East Midlands Obstetric Database. Of these, 2281 (6.7%) delivered preterm (< 37 weeks) by ultrasound dating. The percentage of preterm and post-term cases was calculated for birth weight categories from < 1500 g to > 4499 g at 500 g intervals. The incidence of preterm delivery was estimated for birth weights from < 1500 g to 3400 g. RESULTS: For the 'low birth weight' cut-off of 2500 g, only 64% were actually preterm as assessed by ultrasound, as opposed to 59% as judged by menstrual dates. Nearly 95% of infants weighing over 3000 g are full-term. For birth weights under 2900 g, there is a trend for LMP-derived gestational age to underestimate preterm delivery, by up to 35.5%. By ultrasound dating, 90% of infants under 1800 g are preterm, rising to 98.2% for those under 1500 g. CONCLUSIONS: As nearly 40% of 'low birth weight' infants are born at term, the old classification of 'low birth weight' should be replaced by gestational age-specific percentile categories. Menstrual dates systematically underestimate the prevalence of preterm delivery. Previous estimates of preterm delivery rates based on LMP data have under-stated their true incidence.

Adult↗
PubMed1997

Are Hong Kong babies getting bigger?

OBJECTIVE: To establish recent birth weight trends in Hong Kong. METHOD: A total of 10,512 confinements for the years 1985-86, and 7857 for the years 1995-96 were analyzed. RESULT: There was a significant increase in maternal height, weight at booking, and maternal age, whereas the body-mass index was reduced slightly (P < 0.0001). Parity increased significantly, with the percentage of parous women rising from 44.1% to 55.6% (P < 0.0001). The percentage of female infants decreased from 49.5% to 47.9%. Despite these changes there was no significant difference in mean birth weights between the two groups. When birth weight was controlled for sex, parity, maternal height and weight there was a trivial increase of 15 g over time (P = 0.01). CONCLUSION: Birth weight has reached a plateau in Hong Kong despite a continuing increase in the regions' socioeconomic status, and evidence of improved nutritional well-being.

Birth Weight↗
PubMed1997

The development of a hybrid expert system for the interpretation of fetal acid-base status.

This article presents the development of an expert system for the interpretation of fetal scalp acid-base status. The system consists of logistic transformations, back-propagation neural networks and decision algorithms connected in series. It checks for out-of-range errors and the physiological coherence between measurements. It then determines whether acidosis should be diagnosed, and if so, whether it is more likely to be metabolic, respiratory or mixed. It will also flag those cases where it is difficult to interpret the data in physiological terms. The system was tested on a database of 2174 scalp blood samples collected at the Queens Medical Centre, Nottingham. Of these 88 samples were rejected as erroneous; 13 because of an out-of-range pH alone (> or = 7.48); 73 because more than one measurement was marginally out of range, and two because the relationship between measurements did not make sense. A total of 527 cases (24.2%) were diagnosed as being acidotic; of these, 139 were respiratory, 114 mixed and 274 metabolic. We were unable to fault the system's interpretation when the cases at the margins between diagnostic categories were reviewed clinically.

Acid-Base Equilibrium↗
PubMed1997

Computerised estimation of the baseline fetal heart rate in labour: the low frequency line.

OBJECTIVE: To develop and evaluate a computerised algorithm for the estimation of the fetal heart rate baseline (low frequency line) during labour. DESIGN: Retrospective observational study. METHODS: Fetal heart rate signals were obtained from women in labour using the Nottingham fetal ECG monitor. The computerised algorithm for the baseline estimation was developed for intrapartum applications and is based on averaging modal fetal heart rate values. Evaluation was carried out on sixty cardiotocographic recordings by 12 experts and by the computer. These estimates were compared with those obtained from the computerised system using paired differences and intraclass correlation. RESULTS: The study showed that it is possible to produce a low frequency line from data obtained from intrapartum records. The system could not estimate the low frequency line in four records, whereas experts were also unable to estimate between one and seven tracings. The 95% CI for the paired differences between computer and experts was -12 to 15 bpm, whereas between the experts this was -10 to 10. With the exception of one expert, there was a high concordance between experts and between computer and experts (intraclass correlation > 0.9). CONCLUSIONS: The performance of this computerised algorithm cannot be distinguished from that of experienced clinicians. There were no significant differences between baseline values obtained by the computerised algorithm and those by the clinicians.

Algorithms↗
PubMed1997

Lipid peroxidation in cord blood at birth: a marker of fetal hypoxia during labour.

OBJECTIVE: This prospective study examined purine metabolism in relation to free oxygen radical activity, as reflected by lipid peroxide levels in umbilical cord blood at birth. SETTING: Departments of Obstetrics and Gynaecology and of Chemical Pathology, the Chinese University of Hong Kong, Hong Kong, and Purine Research Laboratory, UMDS of Guy's and St. Thomas' Hospitals, London, UK. METHODS: Umbilical cord arterial and venous blood samples were collected from 132 singleton term deliveries for determination of hypoxanthine, xanthine, inosine, uric acid, organic hydroperoxides (OHP) and malondialdehyde. Oxygen saturation, PO2, pCO2, pH, and base excess (BE) were also measured. RESULTS: There was a significant correlation between umbilical arterial and venous levels of hypoxanthine, xanthine, inosine, uric acid and all acid-base parameters (p < 0.001). Significant arteriovenous differences were observed for all parameters with the exception of inosine, uric acid and OHP. Umbilical arterial xanthine and potassium correlated significantly with OHP, but hypoxanthine, inosine and uric acid did not. In 13 babies classified as severely asphyxiated at birth (umbilical arterial pH <7.15, BE <-8), xanthine and OHP levels were significantly elevated when compared with non-asphyxiated babies. No significant differences were observed for hypoxanthine, inosine or uric acid. CONCLUSION: The findings indicate that OHP, either in cord arterial or venous blood, is the best marker of free oxygen radical activity in the fetus, and that this correlates with other evidence of cellular hypoxia-reperfusion injury. We propose OHP is a better measure of perinatal outcome than either acid-base balance or hypoxanthine.

Adult↗
PubMed1997

Fetal weight estimation by symphysis-fundus height and gestational age.

A new method for estimating the fetal weight is described, based on symphysis-fundus height and gestational age. The relationship between ultrasound-estimated fetal weight, gestational age, and symphysis-fundus height was determined using multiple regression analysis in a low-risk group. The accuracy of the regression formula was tested retrospectively on two target populations: a second low-risk group and a higher risk group undergoing elective delivery. The formula overestimated weight by 3.6%. The standard deviation of the random errors for the first group was 10.3% whereas in the second it was 11.9%. Fetal weight estimation using symphysis-fundus height and gestational age can be performed with an accuracy comparable to that of ultrasound.

Birth Weight↗
PubMed1997

Oxygen free radical activity in the second stage of labor.

OBJECTIVE: To assess fetal cellular injury arising from oxygen free radical activity in relation to the duration of the second stage of labor. PATIENTS AND METHODS: Cord arterial pH, malondialdehyde and organic hydroperoxides levels were determined following vaginal delivery of 326 term singleton pregnancies. Of these, 35 (11%) received epidural analgesia. The length of the second stage was recorded from the time of full dilatation to delivery. RESULTS: Arterial cord pH, malondialdehyde and organic hydroperoxides were significantly correlated with duration of second stage of labor (r=-0.4492; r=0.2542; r=0.2244; respectively, p<0.001). The association of lipid peroxidation products with second stage duration was independent of cord pH. This correlation was unchanged when cases of operative delivery were excluded. However, the relationship lost statistical significance amongst cases who received epidurals. CONCLUSIONS: The duration of the second stage is correlated with raised reactive oxygen species-derived lipid peroxidation products. Caution should be exercised in the management of prolonged second stage of labor.

Adolescent↗
PubMed1996

Reduction of false-positive diagnosis of fetal growth restriction by application of customized fetal growth standards.

OBJECTIVE: To evaluate the clinical performance of fetal growth charts adjusted for individual maternal characteristics. METHODS: The study group consisted of 267 low-risk singleton pregnancies with normal clinical outcome. Mothers were recruited prospectively after the booking visit, then underwent three to five ultrasound examinations for fetal weight estimation. Individual growth curves were generated from these data and the birth weight, based on logpolynomial growth model. Computer software was written to calculate the number of fetal growth curves that cross the tenth percentile limit, based on an unadjusted, average ultrasound standard for our population, compared with the number that cross this limit if it is customized for known pregnancy characteristics such as maternal height, booking weight, parity, and ethnic group. RESULTS: Individual growth trajectories of this group of pregnancies with normal outcome were significantly less likely to cross below the tenth percentile for fetal weight when using customized growth charts than when the unadjusted standard was used (McNemar's test, P < .001). CONCLUSION: The relationship between maternal characteristics and fetal size needs to be considered in the assessment of fetal growth. The use of a customized standard reduces the false-positive rate for the diagnosis of growth restriction in a normal population.

Adult↗
PubMed1996

Estimating the date of confinement: ultrasonographic biometry versus certain menstrual dates.

OBJECTIVE: Our purpose was to evaluate the clinical implications of current pregnancy dating policies in a population where routine ultrasonography is performed in the first half of pregnancy. STUDY DESIGN: A total of 34,249 computer files of singleton pregnancies that had both "certain" menstrual dates and ultrasonographic biometry were retrieved from the East Midlands Obstetric Database. The estimated dates of delivery were calculated by five different methods: menstrual dates alone, ultrasonography alone, or a combination of both with menstrual dates used if the discrepancy with the ultrasonography dates was within 7, 10, or 14 days, respectively. The accuracy of each method in predicting the actual date of delivery was calculated. Differences among methods were evaluated with nonparametric tests. RESULTS: Compared with use of certain menstrual dates, ultrasonographic dating led to a 70% reduction in the number of pregnancies considered postterm. Delivery occurred within +/- 7 days of the estimated date of confinement in 49.5% cases when menstrual dates alone were used and in 55.2% if ultrasonography alone was used; for +/- 10 days, the corresponding figures were 64.1% and 70.3%. Scan dating alone was significantly better in predicting the actual date of delivery than any of the dating policies taking menstrual dates alone or in combination with ultrasonography. CONCLUSIONS: Even if menstrual dates are considered "certain," there is no advantage in taking them into consideration for calculating the expected date of delivery if a dating ultrasonography result is available. Dating by ultrasonographic biometry in the first half of pregnancy results in a more accurate prediction of the delivery date than using menstrual data alone or in combination with ultrasonography.

Biometry↗
PubMed1996

A comparative analysis of second-trimester ultrasound dating formulae in pregnancies conceived with artificial reproductive techniques.

A dataset of 64 pregnancies conceived by artificial reproductive techniques was studied to assess the accuracy of second-trimester dating formulae when these were applied in routine ultrasound clinics in different centers. Dating formulae for biparietal diameter (BPD) and femur length (FL) were derived for a gestational age range of 14-23 weeks. The best fit curves represented linear equations: gestational age (days) = 44.2 + 2 x BPD; and gestational age (days) = 67.4 + 2.3 x FL. Twelve published formulae for biparietal diameter and femur length were reviewed and systematic and random errors were calculated for these formulae when they were applied to second-trimester scan measurements in precisely dated pregnancies. Overall, published dating formulae performed well in predicting gestational age. The 95% confidence interval was 8.3 days for biparietal diameter and 10.2 days for femur length. The study confirms the accuracy of ultrasound dating in routine ultrasound clinics and supports the use of ultrasound measurement alone in preference to menstrual history for dating pregnancy.

Anthropometry↗
PubMed1996

Maternal lean body mass and birth-weight.

Maternal lean body mass at booking was estimated according to a formula employing the body mass index and maternal age in a sample of 511 women who booked in the first trimester of pregnancy. The significance of this parameter in comparison with established predictors of birth-weight such as maternal weight, height, smoking, parity, gestational age and sex of the infant was examined using bivariate correlations and multiple regression analysis. Maternal lean body mass was found to be the most important determinant of birth-weight for gestation percentile. Cigarette smoking had a negative effect on birth-weight which was independent of maternal physique. The effect of maternal size on birth-weight is largely mediated through constitutional and genetic factors rather than nutrition.

Birth Weight↗