ABSTRACT
OBJECTIVE: The aim of the study was to compare clinical and ultrasonographic variables obtained before delivery as predictors of neonatal survival and morbidity in infants weighing =1000 g at birth. STUDY DESIGN: Maternal data available before the birth of singleton infants with birth weights =1000 g who were delivered at the 11 tertiary perinatal centers of the National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Research Units were studied. Births that followed extramural delivery, antepartum stillbirths, multiple gestations, induced abortions, infants with major malformations, and fetuses delivered at <20 weeks' gestation were excluded. Ultrasonographic variables, including estimated fetal weight, obstetrically estimated gestational age, femur length, and biparietal diameter, and clinical variables, such as maternal race, antenatal care, substance abuse, medical treatment, reason for delivery, fetal gender, and presentation, were studied with logistic regression as predictors of neonatal outcome, including intrapartum stillbirth, neonatal death, and survival to 120 days after birth or to discharge from the hospital with or without the presence of markers of major morbidity. RESULTS: Eight hundred eight infants met enrollment criteria; 63 were excluded because of incomplete data and 32 were excluded because of malformations, leaving 713 for analysis, 386 of whom had an ultrasonographic examination within 3 days of delivery that recorded femur length, biparietal diameter, and estimated fetal weight. Forty-two percent of births were the result of preterm labor, 22% were the result of preterm ruptured membranes, 12% were the result of preeclampsia or eclampsia, 9% were the result of fetal distress, 4% were the result of placenta previa or abruptio placentae, and 2% were the result of intrauterine growth restriction. Perinatal mortality before 24 weeks' gestation exceeded 81% (19% stillbirths and 62% neonatal deaths) but declined sharply thereafter. Most survivors born before 26 weeks' gestation had serious morbidity. Fetal femur length and estimated gestational age predicted survival better than did biparietal diameter or estimated fetal weight. Infants who survived with markers of serious long-term morbidity could not be distinguished from those who survived without morbidity markers before delivery by ultrasonography or clinical data. Threshold values for ultrasonographic measurements of biparietal diameter and femur length were developed to distinguish fetuses with no chance of survival. CONCLUSION: Ultrasonographic assessment of either fetal femur length or gestational age predicts neonatal mortality better than do other antenatal tests. No tests accurately predicted neonatal morbidity in infants weighing =1000 g at birth.
Subject(s)
Infant Mortality , Infant, Very Low Birth Weight , Pregnancy Complications/diagnostic imaging , Ultrasonography, Prenatal , Female , Femur/diagnostic imaging , Femur/embryology , Gestational Age , Humans , Infant, Newborn , Logistic Models , Morbidity , National Institutes of Health (U.S.) , Predictive Value of Tests , Pregnancy , Pregnancy Outcome , Survival Analysis , United StatesABSTRACT
OBJECTIVE: Our purpose was to evaluate the relationship between the approach to obstetric management and survival of extremely low-birth-weight infants. STUDY DESIGN: In this prospective observational study we evaluated 713 singleton births of infants weighing < or = 1000 gm during 1 year at the 11 tertiary perinatal care centers of the National Institutes of Child Health and Human Development network of maternal-fetal medicine units. Major anomalies, extramural delivery, antepartum stillbirth, induced abortion, and gestational age < 21 weeks were excluded. The obstetrician's opinion of viability and willingness to perform cesarean delivery in the event of fetal distress were ascertained from the medical record or interview when documentation was unclear. Grade 3 and 4 intraventricular hemorrhage, grade 3 and 4 retinopathy of prematurity, necrotizing enterocolitis requiring surgery, oxygen dependence at discharge or 120 days, and seizures were considered serious morbidity. Survival without serious morbidity was considered intact survival. Logistic regression was used to evaluate the influence of the approach to obstetric management, adjusted for birth weight, growth, gender, presentation, and ethnicity. RESULTS: Willingness to perform cesarean delivery was associated with increased likelihood of both survival (adjusted odds ratio 3.7, 95% confidence interval 2.3 to 6.0) and intact survival (adjusted odds ratio 1.8, 95% confidence interval 1.0 to 3.3). Willingness to intervene for fetal indications appeared to virtually eliminate intrapartum stillbirth and to reduce neonatal mortality. Below 800 gm or 26 weeks, however, willingness to perform cesarean delivery was linked to an increased chance of survival with serious morbidity. Although obstetricians were willing to intervene for fetal indications in most cases by 24 weeks, willingness to perform cesarean delivery was associated with twice the risk for serious morbidity at that gestational age. CONCLUSIONS: The approach to obstetric management significantly influences the outcome of extremely low-birth-weight infants. Above 800 gm or 26 weeks the obstetrician should usually be willing to perform cesarean delivery for fetal indications. Between 22 and 25 weeks willingness to intervene results in greater likelihood of both intact survival and survival with serious morbidity. In these cases patients and physicians should be aware of the impact of the approach to obstetric management and consider the likelihood of serious morbidity and mortality when formulating plans for delivery.
Subject(s)
Cesarean Section , Fetal Death , Infant, Very Low Birth Weight , Female , Gestational Age , Humans , Infant, Newborn , Pregnancy , Prospective StudiesABSTRACT
An upward change in human maternal plasma glucose concentration is known to increase the percent of time spent in fetal breathing during the late third trimester of human pregnancy. We examined the fetal breathing effects of upward change in plasma glucose (after intravenous glucose administration) and downward change (after intravenous insulin administration) at two different times of day (8 AM and 4 PM) at both 24 and 36 weeks of gestation. No change in the percent of time spent in fetal breathing was seen after insulin infusion. Fetal breathing increased after glucose infusion at 36 weeks of gestation but not at 24 weeks. Responses did not differ between tests performed at 8 AM and 4 PM.