Accurate prediction of term birth weight from prospectively measurable maternal characteristics.

OBJECTIVE: To determine whether accurate prediction of individual term birth weight is possible based on maternal characteristics routinely measured remote from term in healthy women. STUDY DESIGN: Two hundred sixty-two nonsmoking, nondiabetic, white gravidas with uncomplicated term gestations were studied. A cross-validated, split-sample multiple regression analysis was performed to evaluate the predictive value of seven maternal characteristics and two fetal characteristics to identify an optimal combination for accurately estimating birth weight. Fifty-nine terms were assessed for predictive accuracy. RESULTS: Significant predictors of term birth weight were gestational age, parity, fetal sex, maternal height, maternal weight and third-trimester maternal weight gain rate. Combinations of these prospectively measurable variables explained 33% of the variance in birth weight and predicted birth weight to within +/- 267 g (+/- 7.6% of individual birth weight). Term fetal macrosomia was predicted with 80% sensitivity using a prediction cutoff of 3,550 g. CONCLUSION: Individual term birth weight can be accurately predicted in normal gravidas using routinely measurable maternal characteristics. Birth weight estimates using our equation are both prospectively derivable from the beginning of the third trimester and more accurate than any previously devised algorithms, including those that incorporate fetal ultrasonographic data. Our equation can also identify pregnancies at risk for fetal macrosomia so that the timing and mode of delivery may be prospectively modified to minimize peripartum risks to both fetus and mother.     

Validation of a birth weight prediction equation based on maternal characteristics

OBJECTIVE: To validate the accuracy of a birth weight prediction equation based on maternal and pregnancy-specific characteristics and to assess its value in predicting fetal macrosomia. STUDY DESIGN: A previously published birth weight prediction equation based on maternal and pregnancy-specific characteristics was used to predict birth weight in 244 Caucasian gravidas with uncomplicated, singleton, term pregnancies. Results were assessed by calculating the mean absolute error, the mean absolute percentage error and the percentage of birth weights correctly predicted to within +/- 10% and +/- 15% of actual birth weight. The sensitivity, specificity and positive and negative predictive value for predicting fetal weight > 4,000 g were calculated. RESULTS: Birth weight was accurately predicted to within an average of +/- 8.1% (+/- 280 g). The percentage of weights accurately predicted to within 15% of actual birth weight was 87%, and the percentage predicted to within +/- 10% was 68%. The sensitivity for predicting fetal weight > 4,000 g was 52%, specificity 90%, positive predictive value 42% and negative predictive value 93%. The area under the receiver operating characteristic curve for predicting fetal macrosomia was 0.83. CONCLUSION: An equation using maternal and pregnancy-specific characteristics can predict term birth weight in gravidas with uncomplicated singleton pregnancies to within +/- 8.1% (+/- 280 g). The accuracy of the method for predicting birth weight > 4,000 g is comparable to that obtained using ultrasonic fetal biometry.     

Hemoglobin, altitude and birth weight: does maternal anemia during pregnancy influence fetal growth?

OBJECTIVE: To investigate the relationship between maternal hemoglobin concentration, altitude and birth weight. STUDY DESIGN: Birth weights in 235 term pregnancies were investigated for their dependence on maternal hemoglobin concentration after other maternal and pregnancy-specific influences on fetal weight were taken into account. The additional predictive value of hemoglobin concentration on birth weight was assessed using multiple regression. Using published data, the relationship of hemoglobin concentration to altitude was determined, as was the effect of increasing altitude on birth weight. The quantitative effect of hemoglobin concentration on birth weight was correlated with the effect of altitude on hemoglobin concentration to assess whether this could account for the known decrease in birth weight with increasing altitude. RESULTS: Birth weights ranged from 2,220 to 4,850 g (mean, 3,505+/-443), and hemoglobin concentrations ranged from 9.3 to 13.5 g/dL (mean, 11.6+/-0.8). Apart from other known predictive variables, the variation in maternal hemoglobin concentrations at constant altitude independently explained 2.6% of the variance in birth weight (r=-.18, P=.003). Term birth weight was reduced by 89 g for each 1.0 g/dL increase in hemoglobin concentration (P<.01). For every 1,000-m increase in altitude, hemoglobin concentration increased by 1.52 g/dL and birth weight decreased by 117 g. CONCLUSION: Birth weight correlates negatively with maternal hemoglobin concentration. This is consistent with the well-known effect of high-altitude exposure during pregnancy, which increases both hematocrit and blood viscosity and lowers birth weight. The quantitative effect on birth weight of increasing maternal hemoglobin concentration at constant altitude is within 13% of the change in birth weight that can be attributed to the change in hemoglobin concentration associated with increases in altitude.     

Ultrasonographic prediction of term birth weight: how accurate is it?

OBJECTIVE: The purpose of this study was to investigate the accuracy of 25 ultrasonic algorithms for the estimation of term fetal weight and to compare these results to an equation that is based on maternal and pregnancy-specific characteristics alone. STUDY DESIGN: Ultrasonography was performed in 82 nondiabetic gravid women at 35 to 41 weeks of gestation. Fetal biparietal diameter, abdominal circumference, head circumference, and femur length were measured. Twenty-five ultrasonic fetal biometric algorithms and an equation that is based only on maternal characteristics were used to predict birth weight. RESULTS: The correlation between predicted and actual birth weight ranged from 0.44 to 0.79 for the ultrasonic algorithms and was 0.60 for the maternal characteristics equation. Ultrasonic algorithms had mean absolute prediction errors that ranged from +/-263 to 646 g (+/-7.5%-18.8%). Accuracy for the maternal characteristics equation was not statistically different from the best performing ultrasonic algorithms (+/-353 g, +/-10.4%). CONCLUSION: Term birth weight estimates that use ultrasonography are generally no more accurate than predictions that are based solely on quantitative assessment of maternal and pregnancy-specific characteristics.     

Predicting fetal weight. Are Leopold's maneuvers still worth teaching to medical students and house staff?

OBJECTIVE: To assess the value of teaching Leopold's maneuvers to medical students and house staff physicians for the purpose of estimating term fetal weight. STUDY DESIGN: Forty-four patients between 37 and 42 weeks of gestation were asked to estimate their fetus's weight upon presentation for delivery. A medical student or house staff physician then performed Leopold's maneuvers to assess fetal weight manually. For comparison, a previously published birth weight prediction equation was used to calculate fetal weight based upon maternal and pregnancy-specific characteristics alone, and obstetric ultrasonography was performed to measure fetal biometric parameters for use with standard ultrasonic fetal weight prediction equations. RESULTS: House staff physicians performed significantly better than medical students in making fetal weight predictions to within +/- 10% of actual birth weight using Leopold's maneuvers (71% vs. 38%, P < .05). House staff who made tactile assessments of fetal weight were able to predict birth weight to within 15% of actual weight more often than mothers making estimations (P < .05), but medical students could not (P = .53). The correlation between predicted and actual birth weights was .60 for Leopold's maneuvers, .45 for maternal estimates of fetal weight, .55 for the birth weight prediction equation and .63 for the best of eight ultrasonic prediction equations tested. CONCLUSION: House staff physicians make more accurate predictions of term fetal weight using Leopold's maneuvers than do medical students. This is presumably due to the increased experience of house staff in using such tactile techniques. Leopold's maneuvers are a useful method of estimating fetal weight and should continue to be taught to both medical students and house staff.     

Geographical variation in relationships between parental body size and offspring phenotype at birth

BACKGROUND: Size and body proportions at birth are partly determined by maternal body composition, but most studies of mother-baby relationships have only considered the effects of maternal height and weight on offspring birth weight, and few have examined the size of effects. Paternal size and body composition also play a role, primarily through the fetal genome, although few studies have investigated relationships with neonatal phenotype. METHODS: Data from the UK, Finland, India, Sri Lanka, China, DR Congo, Nigeria and Jamaica were used to investigate the effects of maternal measures (derived at 30 weeks' gestation, n=16,418), and also paternal size (n=3,733) on neonatal phenotype, for singleton, live-born, term births. RESULTS: After accounting for variation in maternal size and shape across populations, differences in neonatal phenotype were markedly reduced. Mother-baby relationships were similar across populations, although some were stronger in developing countries. Maternal height was generally the strongest predictor of neonatal length, maternal head circumference of neonatal head and maternal skinfold thickness of neonatal skinfolds. Relationships with maternal arm muscle area were generally weak. Effects of paternal height and body mass index were weaker than the equivalent maternal measurements in most studies. CONCLUSIONS: Differences in maternal body composition account for a large part of the geographical variation in neonatal phenotype. The size of the effects of all maternal measures on neonatal phenotype suggests that nutrition at every stage of the mother's life cycle may influence fetal growth. Further research is needed into father-baby relationships and the genetic mechanisms that influence fetal growth.     

Prediction of term birth weight in Hispanic women using an equation based on maternal characteristics

OBJECTIVE: To test the accuracy of a birth weight prediction equation based on maternal characteristics in Hispanic women. STUDY DESIGN: A previously published birth weight prediction equation based on maternal and pregnancy-specific characteristics was used to predict birth weights for 283 normal Caucasian women of Hispanic ethnicity. The accuracy of these birth weight estimates was compared to a similarly selected group of 233 non-Hispanic Caucasian gravidas who were located 2500 miles away. RESULTS: Birth weight predictions for Hispanic women were accurate to within +/- 8.4% (+/- 287 g). The percentages of birth weights predicted to within +/- 15 and +/- 10% of actual values were 84 and 68%, respectively. These results were no different than those that were obtained for non-Hispanic Caucasian gravidas. CONCLUSIONS: A previously derived birth weight prediction equation based on maternal and pregnancy-specific characteristics alone successfully predicts term birth weight in normal Hispanic gravidas to within +/- 8.4% (+/- 287 g).     

A computerized method for accurately predicting fetal macrosomia up to 11 weeks before delivery

OBJECTIVE: To improve the prediction of birth weight and fetal macrosomia by combining sonographically derived fetal biometric data with routinely recorded pregnancy-specific information. STUDY DESIGN: Retrospective data were obtained for 218 normal gravidas who had obstetrical ultrasonography performed within 11 weeks of delivery. Multiple regression was employed to derive a set of equations for predicting birth weight that used different combinations of ultrasonographic and pregnancy-specific variables. RESULTS: A set of 38 unique combination equations was derived to accurately predict birth weight up to 11 weeks before delivery. The equations use different combinations of ultrasonographic and pregnancy-specific variables, so that predictions are still possible in the face of missing data. When ultrasonographic measurements are taken within 3 weeks of delivery, fetal macrosomia is predicted with 75% sensitivity, 93% specificity, and 67% and 95% positive and negative predictive value, respectively. The equations are equally as accurate for primiparous and multiparous women from all racial groups. A jackknifing procedure was used to validate the predictive accuracy of the equations for use with new subjects. CONCLUSION: The combined approach of predicting fetal macrosomia using ultrasonographic fetal measurements and pregnancy-specific characteristics is superior to pre-existing approaches that rely on either method alone. The method can be used up to 11 weeks before delivery, allowing fetal macrosomia to be predicted reliably in low-risk populations sufficiently early for prospective clinical intervention to be undertaken.     

Paternal smoking is associated with a decreased prevalence of type 1 diabetes mellitus among offspring in two national British birth cohort studies (NCDS and BCS70)

AIMS: An association between paternal age and type 1 diabetes (IDDM) among their offspring was recently reported as well as transgenerational responses in humans. This paper aims to assess the association of markers for prenatal exposures with IDDM. METHODS: We analysed data from two birth cohorts in Great Britain on 5214 cohort members from the National Child Development Study (NCDS) and 6068 members of the 1970 British Birth Cohort Study (BCS70) with full information on IDDM and explanatory variables using multivariate logistic regression. RESULTS: IDDM prevalence was 0.7% (95% CI 0.5-1.0%; n=38) in the NCDS and 0.4% (95% CI 0.3-0.6%; n=27) in the BCS70 cohort. Paternal age was not associated with IDDM possibly due to lack of sample power. Unexpectedly, a lowered prevalence of IDDM was observed among offspring of smoking fathers in both cohorts, with a combined odds ratio of 0.44 (95% CI 0.25-0.75). This association could not be explained by maternal smoking prior to, during or after pregnancy, number of siblings, parental social class, maternal and paternal age, or cohort. Maternal smoking in pregnancy did not alter the IDDM prevalence among offspring. CONCLUSIONS: This unexpected finding may be explained by germ-line mutations or other mechanisms associated with paternal smoking. This phenomenon should be investigated and these results should not be used as a justification for smoking. Paternal exposures may be important in determining IDDM risk.     

孕20～24周临床联合超声预测胎儿出生体重的研究

目的:探讨影响孕20～24周胎儿出生体重的相关因素,构建孕20～24周预测胎儿出生体重的公式。方法:前瞻性研究2011年3月至5月在江苏省产前诊断中心超声室行中期(孕龄20～24周)胎儿结构筛查的单胎孕妇235例,孕前月经规则。根据身份证记录孕妇年龄,询问并记录孕前体重;测量孕妇身高及超声检查时的体重,根据末次月经确定孕龄;超声测量胎儿生物学参数:双顶径、头围、腹围、股骨及肱骨;随访孕妇分娩前体重、新生儿出生体重、胎龄及性别。采用逐步多元回归分析方法,通过173例建立中孕期预估胎儿出生体重的公式。用已建立的回归方程前瞻性预测62例孕妇的胎儿出生体重,并验证其准确性。结果:单指标:孕妇孕前体重及BMI、行超声检查时体重及BMI、分娩前体重及BMI、中孕时胎儿腹围、股骨长、肱骨长、胎龄以及超声检查至分娩时的时间间隔与出生体重均有一定关系(P≤0.10),故纳入上述参数逐步多元回归分析,得出预测胎儿出生时体重的方程:预测的出生体重=-501.14+12.52×时间间隔+34.19×孕妇行超声检查时的BMI+8.61×超声检查时测量的胎儿腹围。通过验证,绝对误差值≤250g者56例,占90.32%,相对误差在10%以下者57例,占91.93%。结论:孕妇中孕期BMI、胎儿腹围超声测量值以及该次超声检查至分娩的间隔时间是预测胎儿出生体重的主要参数。     

Determinants of birth size in Northeast Spain

Abstract

Objective: To update knowledge on determinants of newborn body size in Northeast of Spain considering gestational, parental and socio-cultural variables.

Methods: Cross-sectional assessment of 1442 infants from Aragón (Spain), born at term between March 2009 and March 2010. Obstetric, neonatal, socio-demographic and parental anthropometry data were collected during the first infant scheduled health examination. Hierarchical linear regression models were used to explore associations between newborn anthropometry and included variables.

Results: Birth weight was significantly higher in males than in females (130.7?g), when mother did not smoke during pregnancy (126.3?g), in immigrant mothers (113.1?g) and when parity increased (67.1?g per additional birth). Body weight at birth was 16.9?g higher per kg of maternal weight gain during pregnancy, 5.4?g higher per kg of maternal pre-pregnancy weight and 5.1?g higher per cm of maternal height. Birth length was also significantly higher in males than in females (0.87?cm), when mother did not smoke (0.48?cm), in immigrant mothers (0.64?cm), and it was positively associated with parity, maternal anthropometry and paternal height. Newborn anthropometry was not associated with maternal age, educational level or living location.

Conclusions: Independently of gestational age and newborn sex, the main predictors of birth weight and length were maternal pre-pregnancy anthropometry and weight gain during gestation, to smoke during pregnancy, parity and maternal origin. Our results identify potential modifiable factors influencing newborn body size.     

Usefulness of symphysis-fundal height in predicting fetal weight in healthy term pregnant women

BACKGROUND: There are some works reporting that the measurement of the symphysis-fundal height (SFH) of a full-term uterus is a simple method for estimating the fetal weight. AIM: Evaluating the goodness of distance between the symphysis and uterine fundus in predicting both low-weight fetuses and high-weight fetuses, comparing it with the third quarter ultrasound estimation of fetal weight and then assessing the clinical effectivity of symphysis-fundal measurement associated with third quarter echography in predicting birth weight. METHODS: A prospective study was carried out on 96 single physiologically full-term pregnancies. The diagnostic accuracy of the SFH, echographic fetal growth estimated between the 32nd and the 35th week (expressed in percentiles), and of both was expressed as sensitivity, specificity, predictive positive and negative value, likelihood ratios and compared. RESULTS: There was a correlation between the SFH and fetal birth weight. A SFH below 33 cm is predictive of a fetus whose weight is less than 3,100 g whereas a SFH above 34 cm is predictive of a fetus whose weight is more than or equal to 4,000 g. The diagnostic effectiveness of the SFH was not significantly higher than the ultrasound scanning evaluation of fetal weight in the third quarter and could be slightly improved if it is taken into account along with the ultrasound scanning data. CONCLUSIONS: The measurement of the SFH at term may be helpful in foretelling the fetal birth weight and may improve the diagnostic accuracy of the third quarter echographic estimation of birth weight.     

Matrilineal transmission of birth weight in the rhesus monkey (Macaca mulatta) across several generations.

OBJECTIVE: To investigate how secular trends in maternal weight characteristics, in response to living in a permissive laboratory environment, influence intergenerational trends in birth weight in the rhesus monkey (Macaca mulatta) and to assess the role of female offspring in perpetuating these matrilineal traits. METHODS: A multigenerational data set was used to evaluate the relationship between familial and contemporaneous pregnancy factors and infant birth weight across several generations. These records provided 25 years of information on the maternal and paternal ancestries and reproductive histories, gestation lengths, and birth weights for 1321 infants. RESULTS: Pregnancy weight gain, gestation length, and maternal familial factors were the most important predictors of infant birth weight, followed by infant sex, paternity, and maternal pregravid weight (P<.001 for each variable). Furthermore, the trend in fetal growth across generations followed a matrilineal pattern of transmission that was much more pronounced for female than male offspring (P<.001). Although secular increases in maternal pregravid weight and pregnancy weight gain were detected, the upward shift in female birth weight was not explained solely by these changes in maternal weight parameters. CONCLUSION: With the delivery of ample nutrition and health care in a laboratory setting, there was a dramatic increase in the birth weight of daughters within certain matrilines, providing evidence that an intrauterine mechanism transmitted through female progeny can regulate fetal development. Further, the upward trend in female birth weight had a beneficial influence on the reproductive performance of female descendants in those lineages.     

Correctly identifying the macrosomic fetus: improving ultrasonography-based prediction

OBJECTIVE: Our goal was to improve the accuracy of estimating fetal weights among macrosomic fetuses with the traditional measurements of abdominal circumference, femur length, and head circumference. STUDY DESIGN: We used 4831 cases without anomalies from an ultrasonography laboratory database with an estimated fetal weight obtained a maximum of 14 days before delivery. Abdominal circumference, femur length, and head circumference were each regressed on birth weight to obtain estimated fetal weight by abdominal circumference, femur length, and head circumference, respectively. We compared the individual variation for estimated fetal weight by abdominal circumference, femur length, and head circumference by calculating a within-subject standard deviation to quantify the level of disparity. We adjusted the estimated fetal weight to the date of delivery and for dependencies on maternal diabetes mellitus, weight, and height. We then weighted cases with birth weight >4500 g and diabetic cases with birth weight >4000 g 20-fold (weighted estimated fetal weight) for the purpose of creating a favorable bias for classifying these cases. The equation of Hadlock et al, with abdominal circumference, femur length, and head circumference, was applied as a benchmark estimated fetal weight. RESULTS: Of the 4831 newborns, 308 (6.4%) had a birth weight >4000 g, and 56 (1.2%) had a birth weight >4500 g. There were 154 pregnancies complicated by diabetes mellitus; 26 (16.9%) of the resulting infants weighed >4000 g, and 5 (3.2%) weighed >4500 g. At 95% specificity, the weighted estimated fetal weight had a sensitivity of 85.7% at a cut point of 3912 g, compared with a sensitivity of 71.4% at 3604 g by use of the estimated fetal weight of Hadlock et al. CONCLUSIONS: We were able to improve the accuracy of identifying the macrosomic fetus compared to reliance on the equation by Hadlock et al. A fetus was found to be at significantly increased risk for birth weight >4000 g when the estimated fetal weight based on abdominal circumference is larger than that based on either head circumference or femur length or when there is a large within-subject variance in estimated fetal weight based on abdominal circumference, femur length, and head circumference. We also found that there were significantly different groups of patients whose estimated fetal weights require different equations for better estimates. Even given ultrasonographic measurements, taking into account maternal height, weight, and presence of diabetes mellitus can improve macrosomia detection. Although these findings remain to be optimized and validated, the approach used here appears to yield better predictions than the current "one function fits all" approach.     

Optimal Timing of Prenatal Ultrasound in Predicting Birth Weight in Diabetic Pregnancies

ObjectiveThis study sought to determine the optimal timing of ultrasound in the third trimester to predict birth weight accurately in diabetic women with a singleton pregnancy.MethodsA retrospective cohort study of all diabetic women with a singleton pregnancy treated in Halifax, Nova Scotia, was performed. Estimated fetal weight was derived from ultrasound measures using the Hadlock2 equation. The Mongelli equation was used to predict birth weight. The association between gestational age at ultrasound and accuracy of predicted birth weight was assessed, with accuracy as a continuous variable representing the difference between predicted and actual birth weight and as a categorical variable (with four gestational age categories) representing whether predicted birth weight was within, over, or under 250 g of actual birth weightResultsThe cohort of 943 women comprised 121 (12.8%) with type 1 diabetes, 111 (11.7%) with type 2 diabetes, and 711 (75.4%) with gestational diabetes. Ultrasound scans performed at term were the most accurate in predicting birth weight. At this gestational age, the mean difference between predicted and actual birth weight was −30 g (95% confidence interval −109 to −48). After adjusting for maternal body mass index, age, smoking, type of diabetes, and interval between ultrasound examination and delivery, accuracy improved as gestational age at ultrasound increased (P = 0.005). The odds of underpredicting or overpredicting birth weight were not significantly affected by the timing of the ultrasound examination.ConclusionBecause the predictive accuracy of ultrasound prediction of birth weight improves with gestational age, fetal growth assessment at term is recommended to aid with delivery planning in women with diabetes.     

Sonographic prediction of twin birth weight discordance

OBJECTIVE: To assess the accuracy of sonographic prediction of clinically significant twin birth weight discordance (25% or greater) and to determine whether this accuracy is affected by defined fetal and maternal variables. METHODS: Using an established database, we reviewed 338 twin gestations delivered over 10 years as a retrospective cohort. Estimation of fetal weight was calculated by applying the Hadlock formula using composite fetal biometry. Intertwin weight discordance was calculated as the difference in the estimated or actual twin weights (A-B) divided by the weight of the larger twin and was expressed as a percentage. Statistical evaluation included validity (sensitivity, specificity, and predictive values) and reliability assessment of ultrasonographic measurements (intraclass correlation coefficients). Multivariable analysis was performed. RESULTS: Of 338 twin gestations, 192 (57%) twin pairs met inclusion criteria. Sonographic prediction of actual intertwin birth weight discordance of 25% or greater had a sensitivity of 55%, specificity of 97%, positive predictive value of 82%, and negative predictive value of 91%. The reliability of estimating intertwin birth weight discordance by ultrasonography was moderately high (intraclass correlation coefficient =.700; 95% confidence interval [CI].620,.765). Multivariable analysis revealed no significant effects of individual maternal or fetal factors on the accuracy of ultrasonographic prediction of intertwin birth weight discordance. CONCLUSION: Sonographic prediction of actual intertwin birth weight discordance of 25% or greater within 16 days of delivery appears to be a valid and reliable method for clinical use. Predictive accuracy is independent of other identifiable maternal or fetal variables.     

Symphysis-fundus height and pregnancy characteristics in ultrasound-dated pregnancies.

OBJECTIVE: To investigate the relation between maternal and pregnancy characteristics and symphysis-fundus height values at term in an obstetric population dated by sonography. METHODS: Three hundred twenty-five women were recruited from the antenatal clinics of the Queen's Medical Centre, Nottingham, United Kingdom for measurement of fundal height and for ultrasound scans. Symphysis-fundus height measurements were analyzed by multivariate regression analysis in relation to gestational age, maternal height and weight, ethnic group, and smoking. RESULTS: Gestational age and maternal characteristics explained nearly half of the variability in symphysis-fundus height. Gestational age was the most important determinant, followed by maternal weight, parity, and sex of the infant. The other variables were not significantly correlated. CONCLUSION: Maternal characteristics had statistically significant effects on the expected symphysis-fundus height, which suggests that individually adjusted fundal height charts may improve the precision of clinical screening for fetal growth restriction.     

Outcome predictors for patients delivered by cesarean section for fetal distress

Objective: To determine predictive variables identifying infants admitted to neonatal intensive care (NIC) following cesarean section for fetal distress in labor at term.Methods: Two hundred eight patients were studied. Sixty-six patients delivered by cesarean section at term for fetal distress were compared to 142 term patients not diagnosed as fetal distress. The outcome indicator was admission to NIC. Patients diagnosed as fetal distress were studied to determine variables that increased prediction of adverse outcome. Variables studied were patient age, induction of labor, augmentation of labor, epidural anesthesia, birth weight, antepartum complications, and intrapartum complications. Comparisons were by Fishers Exact text and logistic regression.Results: Twenty-six infants were admitted to NIC. Eleven had a diagnosis of fetal distress and 21 had a diagnosis of antepartum complications. Fetal distress was not associated with admission to NIC (P = .26) and had a low sensitivity (42%) and positive predictive value (17%). Antepartum complications, intrapartum complications, and birth weight were associated with admission to NIC (P = .00001) (P = .04) (P = .05). Antepartum complications had a sensitivity of 81% and a positive predictive value of 33% for admission to NIC. The presence of both fetal distress and antepartum complications increased the positive predictive value to 91%. Only one infant was admitted to NIC with a diagnosis of fetal distress without antepartum complications. Positive predictive value 2.4%, negative predictive value 96%. Birth weight when dichotomized at the 5th percentile (2,606 g) had a sensitivity of 20% and a positive predictive value of 50% for admission to NIC. Five of 10 infants with a birth weight below the 5% percentile were admitted to NIC.Conclusion: Antepartum complications coupled with fetal distress in labor are a strong predictor of adverse outcome, which is not altered by cesarean section. There are two groups of patients with fetal distress in labor at term, and the group with antepartum complications or subtle reduction in birth weight are at extreme risk for adverse outcome. It appears that cesarean section for fetal distress may rescue infants without antepartum problems but may not rescue those with a challenging antepartum course, lending credence to the feeling that fetal distress in labor may be an indicator of prior stress in many patients.     

Birth weight and intellectual performance in late adolescence.

The impact of birth weight on cognitive performance in late adolescence was assessed in a study of 20,567 male infants born in Jerusalem between 1964-1970. The 17-year follow-up was performed by matching computerized data base records. Stepwise multiple regression analysis was used to estimate the effect of birth weight on intelligence test scores, adjusting for the influence of ethnic origin, maternal and paternal education, social class (determined by area of residence), maternal age, and birth order. These confounders explained 22% of the variance in intelligence test scores. The adjusted differences in intelligence test scores were significantly lower for groups with birth weight less than 2000 g (-6.5 points), 2000-2499 g (-3.6 points), and 2500-2999 g (-1.6 points) compared with the group weighing 3000-3499 g. Most low birth weight infants achieved intellectual performance within the normal range. However, despite this reassuring finding, low weight at birth in male subjects was found to have a statistically significant independent association with inferior intelligence test achievements in late adolescence.     

Factors affecting fetal weight distribution in women with type I diabetes

Objective To identify factors independently affecting fetal weight in women with type I diabetes.
Design Prospectively recorded data in consecutive women with type I diabetes, between 1975–1992.
Setting Simpson Memorial Maternity Hospital, Edinburgh.
Population Three hundred and two pregnancies with type I diabetes identified before pregnancy, with antenatal care and delivery in the Simpson Memorial Maternity Hospital, a singleton pregnancy, and the same diabetic physician.
Methods Normal ranges for birthweight were established for the total hospital population. All cases and the total population had pregnancy dating by ultrasound. The relation between standardised birth-weight and explanatory variables was investigated using correlation analysis, t tests and χ² tests as appropriate, and subsequently using multiple linear regression.
Results Standardised birthweight in cases, compared with the reference population, showed a unimodal, approximately normal distribution, markedly shifted to the right (mean + 1.26 SD). The most predictive variable was glycated haemoglobin concentration at 27–33 weeks, which explained 6.3% of the birthweight variance, while smoking explained 2.7% and maternal weight 2.0%. There was a trend towards a negative relationship with glycated haemoglobin concentration at 6–12 weeks. Smoking and glycated haemoglobin concentration were strongly intercorrelated.
Conclusions Most of the variance in standardised birthweight remains unexplained, but glycated haemoglobin concentration at 27–33 weeks is the most powerful explanatory variable. Possible reasons why there is not a stronger relationship between markers of maternal glycaemia and birthweight are discussed.