Biomedical subjects

R O Davis

Publications and source records attributed to R O Davis.

At least 19 recordsLinked to original sources

PubMed1998

Pregnancy outcomes following sonographic nonvisualization of the fetal stomach.

OBJECTIVE: To review pregnancy outcomes when two or more ultrasound scans persistently fail to visualize the fetal stomach. METHODS: A computerized ultrasound database was used to identify all fetuses in which two or more serial ultrasound examinations failed to visualize the fetal stomach. Sonographic images were reviewed retrospectively, with the reviewer blinded to outcome data, to confirm persistent nonvisualization. Pregnancy outcome data were obtained from hospital charts and physicians' office records. Fetal karyotypes, when performed, were obtained from amniotic fluid (AF) culture. The ultrasound findings then were compared with fetal karyotype results and pregnancy outcome data. RESULTS: Of 35,569 ultrasound scans performed during 1991-1996, 26 fetuses (0.07%) with persistently nonvisualized stomachs were identified. Structural defects were detected in 17 fetuses (65%), most often involving the cardiothoracic (n = 5), genitourinary (n = 4), and central nervous systems (n = 4). Karyotypes were obtained in 12 fetuses, and four of them were abnormal. Only five of 17 fetuses (29%) with a structural defect survived. In nine of 26 fetuses (35%) with persistently nonvisualized stomachs, no structural defect was identified. Each of these nine fetuses had abnormal AF volume in its surrounding sac, and the overall perinatal survival in fetuses without a structural defect was only 50%. CONCLUSION: Fetuses with persistently nonvisualized stomachs have an increased incidence of structural defects and AF abnormalities and are more likely to have a poor outcome. A detailed ultrasound examination and fetal karyotype analysis should be performed to evaluate fetuses with persistently nonvisualized stomachs.

Congenital Abnormalities↗

PubMed1997

Significance of a false-positive trisomy 18 multiple-marker screening test.

OBJECTIVE: To determine if a false-positive trisomy 18 multiple-marker screening test (all three analytes low: maternal serum alpha-fetoprotein [AFP] at most 0.75 multiples of the median [MoM], unconjugated estriol at most 0.60 MoM, and hCG at most 0.55 MoM) indicates increased risk for obstetric complications or is related to maternal weight. METHODS: We accessed our genetic database to obtain multiple-marker screening test results, fetal karyotypes, and pregnancy outcomes from all patients with a normal multiple-marker screening test (n = 3900) and from all patients with a positive trisomy 18 screening test (n = 103) seen in the prenatal diagnosis clinic from 1992 to 1996. During this period, only maternal serum AFP was adjusted for maternal weight. RESULTS: A positive trisomy 18 screen identified five of 12 trisomy 18 fetuses. Women with a false-positive trisomy 18 screen were heavier (175.6 +/- 43.8 lb versus 159.9 +/- 37.9 lb, P < .001) and younger (29.7 +/- 6.5 years versus 32.3 +/- 6.5 years, P < .001) than women with a normal multiple-marker screening test, but were not at increased risk for pregnancy complications. Weight-adjusting all three analytes reduced the false-positive trisomy 18 screen rate by 42% (from 1.9% to 1.1%) but did not change the trisomy 18 detection rate. CONCLUSION: A false-positive trisomy 18 screening test does not indicate increased risk to develop pregnancy complications and may be related to inadequate correction for increased maternal weight.

Adult↗

PubMed1997

The relationship between maternal characteristics and fetal and neonatal anthropometric measurements in women delivering at term: a summary.

BACKGROUND: We wanted to determine the relationship between a number of maternal characteristics and various fetal and neonatal anthropometric measurements determined by ultrasound and at birth. METHODS: A total of 1205 term singleton maternal-infant pairs were studied. Various ultrasound measurements obtained at 18, 24, 30 and 36 weeks' gestation and neonatal anthropometric measurements obtained at birth were studied in relationship to various maternal characteristics using univariate and multivariate techniques. RESULTS: Black race, female sex, cigarette smoking, drug use, having a previous low birthweight infant, maternal hypertension and being short or thin or failing to gain weight each resulted in a birthweight decrease of 100 to 300 g. The effect of each of these characteristics on each ultrasound measurement, the timing of the effect, and its ultimate effect on neonatal anthropometric measurements are described. CONCLUSION: The data presented in this paper provide a more complete understanding of the relationship between maternal characteristics, infant sex, and various fetal ultrasound and neonatal measurements.

Alabama↗

PubMed1996

Prognostic significance of unexplained elevated amniotic fluid alpha-fetoprotein.

OBJECTIVE: To compare the prognostic values of unexplained elevated amniotic fluid alpha-fetoprotein (AF AFP > or = 2.0 multiples of the median [MoM]) and unexplained elevated maternal serum alpha-fetoprotein (MSAFP > or = 2.5 MoM). METHODS: We accessed a data base containing the results of MSAFP screening tests, genetic amniocenteses, and pregnancy outcome data on all women undergoing second-trimester genetic amniocentesis from October 1988 through August 1994. After excluding all patients whose elevated AFP levels had any identifiable cause (positive AF acetylcholinesterase, AF blood contamination, fetal malformation or aneuploidy, multiple gestation, etc), 5743 cases were analyzed. Relative risks (RR) for selected pregnancy complications were determined. RESULTS: Elevated MSAFP, with any AF AFP, was associated with fetal growth restriction (RR 2.5, 95% confidence interval [CI] 1.4-4.4), stillbirth (RR 3.5, 95% CI 1.4-8.3), preeclampsia (RR 2.8, 95% CI 1.1-7.0), and preterm delivery (RR 2.8, 95% CI 2.3-3.4). Elevated AF AFP, with any MSAFP, was associated with preeclampsia (RR 4.4, 95% CI 2.0-10.0) and preterm delivery (RR 1.7, 95% CI 1.3-2.4). Elevation of both AF AFP and MSAFP was associated with preterm delivery (RR 4.0, 95% CI 2.8-5.7). When elevated AF AFP was found in association with a normal MSAFP, the RR to develop preeclampsia was 4.6 (95% CI 1.9-11.2). CONCLUSION: Maternal serum alpha-fetoprotein is a better predictor of late pregnancy complications than AF AFP. However, unexplained elevated AF AFP appears to be especially predictive of preeclampsia.

Amniotic Fluid↗

PubMed1996

Pregnancy outcome following genetic amniocentesis at 11-14 versus 16-19 weeks' gestation.

OBJECTIVE: To compare pregnancy complications in women having genetic amniocentesis at 11-14 weeks versus those undergoing amniocentesis at 16-19 weeks' gestation. METHODS: A genetics data base was used to identify patients retrospectively, those who had genetic amniocenteses by three experienced operators during a 4-year period. The study group consisted of women who had amniocenteses at 11-14 weeks' gestation. For each study patient (early amniocentesis), two controls (amniocentesis at 16-19 weeks) were identified and matched for maternal age, race, and the number of prior spontaneous abortions. An immediate post-procedure complication was defined as any vaginal bleeding, rupture of membranes, or fetal loss occurring up to 30 days after the amniocentesis. A later complication was defined as any fetal death longer than 30 days after the amniocentesis, any preterm delivery, any infant weighing less than the tenth percentile for gestational age, and any neonatal death. Immediate and later complications were compared between the study and control groups. RESULTS. The study group consisted of 314 patients who were matched to 628 controls. Women who had a genetic amniocentesis performed at 11-14 weeks were significantly more likely to have post-procedure amniotic fluid leakage (2.9 versus 0.2%), post-procedure vaginal bleeding (1.9 versus 0.2%), and a fetal loss within 30 days of the amniocentesis (2.2 versus 0.2%) than women undergoing genetic amniocentesis at 16-19 weeks' gestation. Four of the seven patients (57%) with a fetal loss within 30 days of an early amniocentesis had procedure-related complications, such as amniotic fluid leakage, bleeding, and infection, that caused the pregnancy to be lost. No differences were noted between the two groups in the number of preterm deliveries, later fetal deaths, neonatal deaths, or newborns weighing less than the tenth percentile for gestational age. CONCLUSION: Genetic amniocentesis at 11-14 weeks is associated with more post-procedure complications and a higher fetal loss rate within 30 days of the procedure than a genetic amniocentesis performed at 16-19 weeks' gestation.

Adult↗

PubMed1996

Second-trimester cystic hygroma: prognosis of septated and nonseptated lesions.

OBJECTIVE: To compare karyotypic, ultrasonographic, and prognostic features of septated cystic hygromas and nonseptated cystic hygromas in second-trimester fetuses. METHODS: A computerized ultrasound data base was used to identify fetuses diagnosed with cystic hygromas at 14-22 weeks' gestation. Photographs from the initial ultrasound were reviewed retrospectively for hygroma type (septated or nonseptated) and any abnormal structural findings. Fetal karyotypes were obtained from amniotic fluid, aspiration of hygroma pouches, or fetal tissue culture. Pregnancy outcome information was obtained from hospital charts and physician office records. Ultrasound findings were then compared with fetal karyotype results and pregnancy outcome data. RESULTS: From 1990 to 1995, 61 fetuses with cystic hygromas were identified. Karyotypes were obtained in 55 fetuses, and pregnancy outcome was available for 59. Abnormal karyotype was present in 42 of 55 fetuses (76%). The most common chromosomal abnormality in septated hygromas was the 45,X karyotype. Trisomy 21 was the most common chromosomal abnormality in nonseptated hygromas. Compared with fetuses with nonseptated cystic hygromas, those with septated cystic hygromas were more likely to be aneuploid (33 of 39 [85%] versus nine of 16 [56%]; P = .03), more likely to develop hydrops (27 of 45 [60%] versus three of 16 [19%]; P = .005), and less likely to be live-born (one of 44 [2%] versus four of 15 [27%]; P = .01). CONCLUSIONS: Fetuses with septated cystic hygromas are more likely to be aneuploid and to develop hydrops, and thus are less likely to be survive than fetuses with nonseptated hygromas.

Adult↗

PubMed1996

Quantification of normal head morphometry of stallion spermatozoa.

The heads of stallion spermatozoa were analysed by computer automated sperm head morphometry and the morphometric values of the major subpopulations of sperm heads were assessed. The criteria for normal dimensions of stallion sperm heads are proposed based on the analysis of these measurements. Semen samples were collected from 10 fertile and 10 subfertile stallions, processed by a standard method, smeared onto microscope slides and stained using haematoxylin. At least 200 properly digitized sperm heads were analysed from each stallion. The measurements for length, width, area, perimeter and width/length were recorded for each stallion. All sperm head measurements were placed in a statistical database and multivariate cluster analysis performed. Mean measurements for all parameters of the major clusters of fertile and subfertile stallions were compared by analysis of variance. The ranges of the values of the major clusters of fertile stallions were applied to all stallions to determine the percentage of normal sperm heads for each stallion. The mean values for length, width, area and perimeter in the major cluster of sperm head dimensions of fertile stallions were significantly different from those of the subfertile stallions (P < 0.001). The range of values of the major cluster of fertile stallions was length = 4.9-5.7 microns, width = 2.5-3.0 microns, width/length = 0.45-0.59, area = 10.3-12.1 microns2, and perimeter = 12.9-14.2 microns. On the basis of these values, a significantly (P < 0.001) higher percentage of normal sperm heads were found in the fertile group than in the subfertile group of stallions (52% versus 19%).

Analysis of Variance↗

PubMed1995

The effect of cigarette smoking on neonatal anthropometric measurements.

OBJECTIVE: To estimate the effect of maternal cigarette smoking on birth weight, crown-heel length, and ten other neonatal anthropometric measurements. METHODS: Data are from a cohort study on risk factors for fetal growth retardation (FGR) in multiparous women conducted from December 1985 through October 1988. Information on smoking status was collected four times during pregnancy. Data analysis included 1205 singleton infants of women delivering at term. Neonatal anthropometric measurements were obtained within 48 hours of birth, including birth weight, crown-heel length, ponderal index, head and abdominal circumferences, arm length and circumference, femur length and thigh circumference, and triceps, thigh, and subscapular skinfold measurements. Analysis of covariance models were used to assess the independent effect of smoking on each neonatal measurement. RESULTS: Neonates born to women who reported smoking during the first trimester had a 0.6-1.9% reduction in most neonatal anthropometric measurements, resulting in an overall reduction of birth weight of 130 g (4%). Neonates born to women who continued to smoke throughout pregnancy had an average adjusted reduction in birth weight of 189 g (5.9%), compared with a 55 g (1.7%) reduction for neonates born to women who stopped smoking after the first trimester. For women who continued to smoke throughout pregnancy, an increased number of cigarettes smoked was associated with increased reductions in birth weight and neonatal chest and abdominal circumferences. For women who stopped smoking after the first trimester, stopping was a better predictor of neonatal anthropometric measurements than the number of cigarettes smoked early in pregnancy. CONCLUSIONS: Except for the ponderal index, all neonatal anthropometric measurements studied showed some negative effect of maternal cigarette smoking. Head circumference is the measurement least reduced. Smoking cessation is a better predictor of infant size than the number of cigarettes smoked in the first trimester.

Adult↗

PubMed1995

Application of multivariate cluster, discriminate function, and stepwise regression analyses to variable selection and predictive modeling of sperm cryosurvival.

OBJECTIVE: To develop a mathematical model that predicts sperm cryodamage based on the kinematic characteristics of seminal sperm as detected by computer-aided sperm analysis (CASA). DESIGN: Computer-aided sperm analysis was performed on donor semen before and after freezing. An iterative multivariate statistical analysis technique was developed to identify sperm subpopulations and to select the best variables for modeling. Stepwise, multivariate regression was performed on the selected subpopulations to predict the post-thaw percentage of motile sperm from prefreeze kinematic values. SETTING: Andrology laboratories, IVF laboratories, and sperm cryobanks. PARTICIPANTS: Semen donors in an academic research environment. MAIN OUTCOME MEASURES: Identification of predictive kinematic variables; number of sperm subpopulations per sample; number of kinematic variables per subpopulation; prediction error for subpopulation membership; and an equation for prediction of post-thaw percentage of motile sperm from prefreeze CASA variables. RESULTS: The number of subpopulations for each specimen was predicted by 3 to 5 kinematic variables. Straight-line velocity (VSL) and linearity were the most commonly predictive primary variables, whereas curvilinear velocity and amplitude of lateral head displacement were the most commonly predictive secondary variables. The best linear model predicted the post-thaw percentage of motile sperm from the difference in VSL between the subpopulation with the highest value and the subpopulation with the lowest value in each prefreeze specimen. CONCLUSIONS: A small number of consistent kinematic variables accurately described physiologic subpopulations of sperm in prefreeze and post-thaw specimens from different men. An equation based on the characteristics of these subpopulations predicts the post-thaw percentage of motile sperm (i.e., sperm recovery) from simple prefreeze kinematic variables. This equation could improve specimen screening by eliminating the requirements for freezing and thawing in order to identify a specimen's vulnerability to cryodamage.

Cell Survival↗

PubMed1995

A standardized test for visual analysis of human sperm morphology.

OBJECTIVES: To develop a method to train and test simultaneously a large number of observers in the practice of visual sperm morphology analysis. DESIGN: Photographs of fixed and stained sperm were prepared. Fields of suitable sperm images were selected and individual images were numbered on each negative. Two tests, which contained a total of 100 sperm images, were created. Thirty images in each test consisted of three repeats of 10 images, while 70 images in each test were unique. The tests were administered to individuals participating in an American Fertility Society postgraduate course. Sperm images were projected on a screen and participants classified each sperm using the method that was used in their own laboratory. SETTING: Postgraduate course of The American Fertility Society. RESULTS: The majority of individuals participating in the tests used some version of the World Health Organization method. The group using the Strict method reported a lower value for the percentage of normal sperm than the groups using the other methods. The variability for the percentage of normal sperm was highest for the Strict method. The degree of classification reversal, i.e., classifying a sperm as normal during one repeat and then reversing the classification during another repeat, was high for all groups (26% to 44% of the classifications). Some degree of improvement was seen from test 1 to test 2. CONCLUSIONS: It is possible to develop efficient and inexpensive methods to train observers to perform the sperm morphology assay. Such methods also enable the objective measurement of the acquisition of proficiency, comparison between different classification methods, and identification of specific differences between observers. Such methods will become more important with implementation of the Clinical Laboratory Improvement Act.

Humans↗

PubMed1995

Derivation and reliability of kinematic measures of sperm motion.

Studies of sperm movement are relevant in the diagnosis of sperm function and in investigations of cellular biology. Such studies have been traditionally performed by analysing the kinematics of the flagellum or the head. Analysis of the flagellum can provide insights into the cell biological mechanisms responsible for the control of movement. However, the mathematical correspondence between head kinematics and flagellum kinematics is not unique. Therefore, it is not possible to use head kinematics to obtain detailed insights into cell mechanisms or physiology. The accuracy and precision of kinematic measurements are limited by a number of technical and biological factors. Therefore, the interpretation of kinematic data is dependent on a thorough understanding of the assumptions and conditions underlying the analysis. Evaluation of the reliability of kinematic measurements has suffered because no absolute standard for measurement has existed. The development and application of a new standard based on images which were simulated using the equations of motion is described. Because the kinematics of these images are known prior to empirical measurement, the performance of different methods can be determined absolutely. Some kinematic measures are unreliable because they are inappropriate analogues for engineering concepts. The development and use of appropriate engineering measures for the frequency and amplitude of sperm motion is also described. Some types of sperm motion cannot be analysed using kinematic measures (e.g. hyperactivated movement). The concept of the fractal dimension as a more accurate measurement for such motions is introduced. It is concluded that kinematic measurements of sperm motion can provide valuable information about cell biological mechanisms (in the case of the flagellum) and about general membrane and axoneme function (in the case of the head) when the measurements are made under the appropriate conditions, when standard techniques are followed, and when the assumptions underlying the analysis are well understood.

Biomechanical Phenomena↗

PubMed1995

Use of differentiated cholinergic and second messenger endpoints to evaluate cholinesterase inhibitors.

1. The effects of organophosphorus compounds on the cholinergic properties of a mouse septal neuronal cell line, SN56, were investigated. Treatment of the cells with 10 mumol/L paraoxon or 10 mumol/L diisopropylphosphorofluoridate (DFP) resulted, respectively, in rapid 27- and 11-fold increases of intracellular acetylcholine content. 2. Time-course studies showed that paraoxon maintained its efficacy whereas the effects of DFP decayed quickly, possibly due to rapid hydrolysis and inactivation of DFP in the growth medium.

Acetylcholine↗

PubMed1995

Fetal myelomeningocele. Is antenatal ultrasound useful in predicting neonatal outcome?

The objective of this study was to determine if an ultra-sound examination, when performed in the third trimester immediately preceding delivery, is useful in predicting outcome in infants with a myelomeningocele. A retrospective review was undertaken of prenatal ultrasound records and pediatric outcome data on fetuses with isolated myelomeningocele referred to our institution after 28 weeks' gestation during a three-year period. Macrocephaly proved to be the one antenatal ultrasound finding that most correlated with later poor outcomes in infants with myelomeningocele. Macrocephalic fetuses had a longer mean hospital stay after birth and were more likely to have significant respiratory and feeding difficulties. No fetus with macrocephaly had a normal mental score, and all had severe motor deficits on later follow-up testing. The ultrasound diagnosis of macrocephaly identified a group of fetuses with myelomeningocele, who were at highest risk of neonatal problems and developmental delay. Cesarean delivery and aggressive medical treatment of complications did not improve the outcome in these infants. This finding will be useful when counseling patients regarding route of delivery and in pediatric decisions regarding treatment of complications.

Adult↗

PubMed1994

The effect of corticosteroid therapy in the very premature infant. March of Dimes Multicenter Study Group.

OBJECTIVE: Our purpose was to determine the efficacy of maternal corticosteroid therapy between 26 and 31 weeks' gestation. STUDY DESIGN: The data in this study were derived from 32,658 women who participated in the March of Dimes-sponsored multicenter prematurity prevention program. Of the 432 women who were delivered at 26 to 31 weeks, 67 received betamethasone before delivery and 365 did not. The frequency and relative risks of adverse outcomes, including respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, and neonatal death were compared for each of two gestational age periods by means of univariate and multivariate techniques. RESULTS: When betamethasone was administered > or = 2 days before delivery (n = 45), there was a lower incidence of respiratory distress syndrome in both the 26 to 28 week group (53.9% vs 86.5%, p = 0.008) and the 29 to 31 week group (25.0% vs 59.1%, p = 0.0003). The rate of intraventricular hemorrhage was less in the betamethasone group at 26 to 28 weeks (15.4% vs 32.3%, p = 0.17), but the difference reached statistical significance only at 29 to 31 weeks (3.1% vs 16.5%, p = 0.029). Neonatal death occurred significantly less often in infants who were delivered at 26 to 28 weeks when their mothers received betamethasone compared with infants of the same gestational age whose mothers did not receive betamethasone treatment (0% vs 34.6%, p = 0.01). In a regression analysis of infants born between 26 and 31 weeks in which birth weight, gestational age, race, infant sex, and tocolytic use were controlled, the odds ratio for respiratory distress syndrome associated with betamethasone use was 0.20 (0.10, 0.42), for intraventricular hemorrhage 0.26 (0.08, 0.90), and for neonatal death 0.14 (0.02, 1.09). Insufficient numbers of women were given betamethasone before 26 weeks for analysis. CONCLUSION: Betamethasone appears to significantly reduce neonatal death and the morbidity between 26 and 31 weeks' gestation.

Betamethasone↗

PubMed1994

Relationship between amniotic fluid and maternal blood nutrient levels.

To study the relationships between amniotic fluid and maternal blood nutrient concentrations, we obtained amniotic fluid and blood samples simultaneously from 76 pregnant women at around 17 weeks gestation. Folate and vitamin B-12 levels were measured by microbiological assay and radioassay, respectively, and zinc, copper and iron levels by atomic absorption spectrophotometry. Mean concentrations of plasma and red blood cell (RBC) folate and plasma copper of the pregnant women were 38 (+/- 1, SD), 1,501 (+/- 374) nmol/L, and 32.7 (+/- 4.8) mumol/L, respectively, all of which were higher than those of healthy non-pregnant controls (p < 0.001). Mean concentrations of plasma vitamin B-12, zinc and iron levels and RBC zinc were 320 (+/- 130) pmol/L, 12.2 (+/- 2.3), 21.7 (+/- 6.1) and 177 (+/- 30) mumol/L and these were similar to those of non-pregnant controls. Amniotic fluid folate, zinc, copper and iron concentrations were 21 (+/- 13) nmol/L, 1.4 (+/- 0.6), 1.7 (+/- 0.6) and 6.8 (+/- 2.1) mumol/L, respectively, which were significantly lower than plasma levels (p < 0.001). However, this relationship was reversed for vitamin B-12 (650 +/- 420 pmol/L). Significant correlations were found between amniotic fluid and maternal plasma and RBC for folate, and between amniotic fluid and maternal plasma for vitamin B-12 (p < 0.001). No such correlations were observed for zinc, copper and iron. There was no correlation between amniotic fluid and/or blood nutrient concentrations and pregnancy outcome including birth weight of infants.

Adult↗

PubMed1994

Unexplained elevation in maternal serum alpha-fetoprotein and subsequent fetal loss.

OBJECTIVE: To examine the frequency and timing of fetal death and its association with maternal serum alpha-fetoprotein (MSAFP) levels. METHODS: Pregnancy outcomes were evaluated in 6927 predominantly middle-class women (83% white, 17% black) who had second-trimester MSAFP determinations performed in our laboratory. All cases of multiple gestation, preexisting fetal death, and fetal malformation were excluded. RESULTS: The overall fetal death rate was 13 per 1000 (n = 90). Black women had a higher fetal death rate than white women (35.6 per 1000 versus 8.4 per 1000; P < .001). One hundred forty-eight women (2.1%) had an adjusted MSAFP multiples of the median (MoM) value of at least 2.5, which was not explained by multiple gestation, congenital anomaly, or preexisting fetal death. As the MSAFP increased, the fetal death rate increased (MoM less than 2.0, 11 per 1000; MoM 2-2.49, 29 per 1000; MoM 2.5 or greater, 95 per 1000; P < .001). Despite the increased risk of fetal death in the elevated MSAFP group, most fetal deaths (84%) occurred in women with levels below 2.5 MoM. Furthermore, the timing of fetal loss was significantly different between the group less than 2.5 MoM and the group at or above 2.5 MoM. Fetal death occurred at or after 26 weeks in 45% of the women with normal MSAFP, compared with only 14% of women with high MSAFP (at least 2.5 MoM) (P = .023). CONCLUSIONS: Women with unexplained elevations in MSAFP are at increased risk for fetal loss, with most of the losses occurring in the second trimester. Because many of these fetal deaths occur at gestational ages when the neonatal survival is very low, it is unlikely that antepartum fetal surveillance aimed at early delivery would substantially increase fetal salvage.

Chi-Square Distribution↗

PubMed1994

Risk factors for fetal death in white, black, and Hispanic women. Collaborative Group on Preterm Birth Prevention.

OBJECTIVE: To document the relation between stillbirth and various demographic, obstetric, and medical risk factors. METHODS: We analyzed the risk factors and medical origins of 403 stillbirths. The population studied included 34,350 births occurring during the March of Dimes Preterm Birth Prevention Trial. All births occurring in five perinatal centers from 1982-1986 were included in the analysis. Stillbirth was defined as those infants born at 20 weeks' gestation or later whose Apgar score was 0 at 1 and 5 minutes. RESULTS: Stillbirth occurred in 1.2% of all births. Fifty-one percent occurred before 28 weeks and only 18% were at term. Blacks had a greater risk of stillbirth when compared to other women. Prior preterm delivery yielded nearly a two-fold increase in the risk of stillbirth. Preeclampsia, chronic hypertension, and class A or class B-R diabetes were not associated with an increased risk of stillbirth. Other medical factors (hemoglobinopathies, Rh sensitization) resulted in a greater than sixfold increase in the rate of stillbirth, and congenital anomalies resulted in a fivefold increase. Abruption was associated with a 12-fold increase in the risk of stillbirth; nearly 14% of all stillbirths were associated with abruption. CONCLUSION: Eighty-two percent of all stillbirths occurred before term, and more than 50% occurred before 28 weeks. The majority of stillbirths were not explained by medical complications, but instead were often associated with other risk factors related to preterm birth. Further investigations are needed to understand the complex etiology of stillbirth.

Adolescent↗

PubMed1993

Maternal risk factors and their influence on fetal anthropometric measurements.

OBJECTIVE: Our purpose was to determine if and when maternal risk factors and fetal sex have an impact on specific fetal anthropometric measurements assessed by ultrasonography. STUDY DESIGN: Serial ultrasonographic examinations were performed on 1205 fetuses of indigent multiparous women who ultimately gave birth at term. Femur length, abdominal circumference, and head circumference measurements were obtained at mean gestational ages of 18, 25, 31, and 36 weeks, and an estimated fetal weight was calculated. At birth the infant was weighted and head circumference, abdominal circumference, femur length, and crown-heel length measurements were made. Regression analyses were used to determine the effect on each measurement of maternal race, height, body mass index, hypertension, weight gain, smoking, previous low birth weight, and fetal sex. RESULTS: Acting through their effect on head circumference, abdominal circumference, and fetal length, each of the risk factors and female sex were shown to have a negative effect on fetal weight. The timing of the impact, its magnitude, and the specific anthropometric measurement affected were different for each of the risk factors. CONCLUSIONS: The impact of maternal risk factors and fetal sex on estimated fetal weight has been demonstrated to occur first in specific gestational age windows and is mediated through effects on specific fetal anthropometric measurements.

Anthropometry↗