Effect of third-trimester premature rupture of membranes on fetal breathing movements: a prospective case-control study.

Fetal breathing movements were examined in 44 women with premature rupture of membranes. All had previously uncomplicated singleton pregnancies (28 to 41 weeks). Of these 44 women, 13 had complications based on later amnionitis/neonatal infection or antepartum fetal distress. Thirty-one normal antepartum patients, matched for gestational age, served as a normal control group. These women had intact membranes and were without any known or suspected maternal, fetal, or neonatal complications. Fetal breathing movements were found in 90% of cases in the control group, compared with 65% in the 31 women with premature rupture of membranes (p less than 0.05). In the group of 13 women with premature rupture of membranes and complications, the incidence of fetal breathing movements was 38%. Therefore, it is possible that the absence of fetal breathing movements can be due to premature rupture of membranes alone. There was a statistically higher incidence of low-birth-weight infants and low Apgar scores in the group of 13 women with premature rupture of membranes and complications compared with the group of 31 women with premature rupture of membranes.

Genetic amniocentesis: impact of placental position upon the risk of pregnancy loss.

Although it is generally believed that a transplacental tap increases the risk of pregnancy loss associated with genetic amniocentesis, objective data are lacking. To quantitate the risk of transplacental amniocentesis, pregnancy outcomes were compared in 998 consecutive patients in whom amniocentesis was performed under direct real-time sonographic guidance. This technique allows visualization of the path of the needle during insertion and documents with certainty whether the placenta has been traversed. A transplacental approach was necessary in 347 patients (35%). The incidence of spontaneous abortion, antepartum stillbirth, prematurity (less than 37 weeks), and low birth weight (less than 2500 grams) was identical in patients undergoing both transplacental and nontransplacental amniocenteses. The similar rates of pregnancy loss in these two groups indicate that when midtrimester transplacental amniocentesis is ultrasonically guided, it is associated with little if any increased risk.

A comparison of the reliability of the estimated date of confinement predicted by crown-rump length and biparietal diameter.

First trimester crown-rump length (CRL) followed by a second-trimester biparietal diameter (BPD) were sonographically measured in 27 patients. Each value was independently used to prospectively predict an estimated date of confinement. The actual delivery date was compared with the estimated dates of confinement predicted by the CRL and the BPD. The mean error in predicting the actual date of delivery by CRL was 7.73 days as opposed to 7.65 days with the BPD. This difference is not statistically significant (p greater than 0.9). In both methods there was a greater tendency to overestimate the actual date of delivery. Contrary to widespread belief, the present study shows that a second-trimester BPD is as accurate as a first-trimester CRL in establishing an estimated date of confinement. Additional benefits of second-trimester scanning include the ability to determine placental localization, evaluate amniotic fluid volume, and exclude many congenital abnormalities.

Ultrasonic methods of predicting the estimated date of confinement.

The present study examines the relative accuracy of 2 ultrasonic methods of predicting the estimated date of confinement (EDC). The first technique, mean projected gestational age (MPGA), utilizes 2 fetal biparietal diameter (BPD) readings between 19 and 30 weeks' gestation with at least a 3-week interval between examinations. The 2 values are fitted to the mean of the standard curve as closely as possible and an EDC is predicted. The second method, growth adjusted sonographic age (GASA), is based on 1 BPD measurement in the second trimester and another in the third. The first is plotted on the mean and then readjusted depending on the percentile into which the second falls (below 25, 25 to 75, above 75). The EDC was blindly predicted in 120 patients, 60 by the MPGA method and 60 by the GASA technique. These were compared with 60 controls whose EDCs were predicted on the basis of excellent clinical dates. The interval between the predicted EDC and the actual delivery date was calculated for each patient and the results were compared. There was no statistical difference between the 2 techniques.

Comparative newborn anthropometric data in symmetric versus asymmetric intrauterine growth retardation.

Autopsy studies have shown that the fetal liver is more severely affected than the brain in asymmetric fetal intrauterine growth retardation (IUGR). This "brain-sparing" concept has led to the suggestion that ultrasonic measurements of biparietal diameter (BPD) are of limited value in detecting IUGR since the BPD is an indirect reflection of head and brain size. This study compares the effects of asymmetric and symmetric IUGR on newborn anthropometric measurements, including head circumference (HC), birth weight (BW), length (L), and ponderal index (Pl) in 33 growth-retarded infants divided into two groups, asymmetric (uteroplacental failure) and symmetric (maternal smoking, drug exposure, congenital anomalies, intrauterine infection), on the basis of the etiology of the IUGR. The percentage reduction in size from mean values for the same gestational age was calculated for each parameter. None of the newborn parameters were useful in distinguishing between infants with asymmetric and those with symmetric IUGR. Particularly noteworthy is the fact that the percentage decrease in HC was similar in both groups. Therefore, the concept of absolute "brain sparing" in asymmetric IUGR is erroneous, and ultrasonic measurements of BPD should be of value in detecting this form of IUGR.

Ultrasonic growth patterns in normal and discordant twins.

Prior studies on twin biparietal growth have resulted in conflicting conclusions. This study was designed to establish definitive criteria based on both ultrasonic biparietal diameter (BPD) and newborn anthropometric data for normal versus abnormal growth in multiple pregnancies. Fetal BPD and newborn head circumference values among concordant twins were similar to those of appropriate for gestational age (AGA) singletons at all gestational ages. Singleton standards can therefore be applied to evaluate the adequacy of twin BPD growth even in the third trimester. Ultrasonic criteria for the diagnosis of discordancy include an intrapair difference in BPD of 5 mm or more and an intrapair difference greater than 5% in ultrasonically measured fetal head circumferences. Discordant BPD growth noted prior to the third trimester suggests twin-transfusion syndrome and is associated with a high perinatal mortality. In contrast, divergent BPD growth beginning after 30 weeks' gestation appears to have a better prognosis.

Prediction of intrauterine growth retardation via ultrasonically measured head/abdominal circumference ratios.

This prospective study examines the reliability of ultrasonically measured head/abdominal (H/A) ratios in detecting uteroplacental insufficiency (UPI)-related intrauterine growth retardation (IUGR) in 47 patients. Normal H/A ratios were found in 37 (79%) fetuses. None of these infants was classified as small for gestational age (SGA) on newborn pediatric evaluation. Ten fetuses (21%) had H/A ratios greater than +2 SD for gestational age. On this basis, UPI-related IUGR was correctly predicted in all 10 infants. It is concluded that the H/A ratio is a sensitive indicator of UPI-related IUGR. Moreover, this technique is particularly valuable in patients referred for initial scanning after 30 weeks' gestation when it is difficult to distinguish accurately between true IUGR and an "error in dates" on the basis of biparietal diameter (BPD) measurements alone.

Abnormal fetal growth patterns. Ultrasonic diagnosis and management.

Diagnostic ultrasound is a useful tool in the management of high-risk pregnancies and provides valuable information about abnormal fetal growth patterns including excessive fetal size and intrauterine growth retardation. Two patterns of growth retardation can be distinguished ultrasonically. Fetuses exhibiting "reduced growth potential" type patterns have little risk of fetal distress and are readily recognized as small for gestational age at birth. Fetuses suffering from uteroplacental insufficiency frequently exhibit a pattern of biparietal growth arrest in the third trimester. These fetuses have a high risk of fetal distress and should be closely monitored with other parameters of fetal-placental function including serial estriols and oxytocin challenge tests. Utilizing conventional pediatric growth criteria, the existence of intrauterine growth retardation is often unrecognized in this latter group.