Preliminary experience with a prospective protocol for planned vaginal delivery of triplet gestations.

OBJECTIVE: The objective of the study was to evaluate a protocol for vaginal delivery of triplet gestations. STUDY DESIGN: All women with triplet gestations managed between January 1, 1995, and December 31, 1997, by University Medical Center's perinatal practice were offered enrollment in our vaginal delivery protocol. Our protocol offered attempt of vaginal delivery if triplet A was in vertex presentation, fetal monitoring was possible, and there were no other obstetric contraindications. Twenty-three triplet gestations were identified; 8 achieved vaginal delivery. Outcome parameters investigated included neonatal mortality, Apgar scores, neonatal intracranial hemorrhage, arterial cord pH, neonatal weight, and length of postpartum hospital stays of mother and neonates. All parameters were analyzed with analysis of variance and the Student t test as appropriate with the JMP 3.1 statistics program (Cary, NC). RESULTS: Twenty-three sets of triplets were enrolled. Eight sets were delivered vaginally. Eight of 9 patients (88.9%) who attempted trial of labor were delivered vaginally, 1 of which was a vaginal birth after cesarean section. The remaining triplet gestation failed to progress at 4-cm dilation. Twelve sets of triplets had a nonvertex-presenting triplet and were delivered by the cesarean route. The remaining 2 triplet gestations were delivered by the cesarean route because of inadequate fetal monitoring. Neonatal survivals were 100% for both groups. No significant differences in neonatal mortality, Apgar scores, intracranial hemorrhage, arterial cord blood pH, hospital or neonatal intensive care unit stay of neonate, neonatal weight, and change in maternal or neonatal blood cell count were noted. There were no cases of grade III or IV intraventricular hemorrhage in either group. A significant reduction in postpartum hospital stay of mother was noted in the vaginal delivery group (2.8 vs 4.5 days, P <.001). The mean gestational age at delivery was significantly lower for the vaginal delivery group (31.3 vs 34.0 weeks, P <.02). The mean neonatal weight for the vaginal delivery group was significantly lower (1758 +/- 473 vs 2022 +/- 407 g, P <.02). There were no significant differences in outcome parameters for the first, second, and third triplets within each group when compared with each other or with the other study group. One patient who underwent vaginal delivery had retained products of conception and required curettage. A single fetal death occurred at 22 weeks' gestation from twin-twin transfusion, with the remaining triplets being delivered vaginally at 35 weeks' gestation. Cesarean hysterectomy was required in 1 case for uncontrollable bleeding at the time of cesarean delivery. Perinatal complications occurred in a large number of patients, with the incidence of premature labor 47. 8% (n = 11), that of preterm premature rupture of membranes 26.1% (n = 6), and that of preeclampsia 34.8% (n = 8). CONCLUSION: In selected cases vaginal delivery of triplet gestations can be accomplished without increased maternal or neonatal morbidity and mortality and may significantly decrease maternal hospital stay and postoperative morbidity.

Accuracy of portable glucose meters for rapid determination of amniotic fluid glucose levels.

This study was designed to evaluate the accuracy and feasibility of use of three commercially available portable blood glucose meters to measure amniotic fluid glucose(AFG) levels as compared to an accepted laboratory standard. A prospective study of amniotic fluid from 101 consecutive amniocenteses was performed. Glucose concentration in the amniotic fluid was assessed by hexokinase method in our hospital laboratory (control) and by using three portable meters: Advantage (ADV) (Boehringer Mannheim), Glucometer Elite (ELT) (Bayer), and One Touch II Hospital (T-2) (Lifescan). Twenty consecutive amniotic fluid samples were sent to the laboratory in two vials, the first without additive and the second with potassium oxalate to prevent metabolic activity, to assess the effect of cellular metabolism and time delay on amniotic fluid glucose concentrations. Data are reported as mean +/-SE and were assessed by one-way ANOVA. Of the 101 patients studied, 29 were of gestational age > or = 20 wks. The remaining 72 patients were < 20 wks. All three ambulatory meters demonstrated a linear relationship with control (all P < 0.001). Given a slope of almost 1.0 (m = 0.94) and a y-intercept approaching zero (b = 4.3), the OT2 proved to correlate best with control. ELT: (r2 = 0.55, m = 0.79, b = 22.2) and ADV: (r2 = 0.74, m = 1.45, b = 16.9) both overestimated amniotic fluid glucose. When AFG was < 30 mg/dl via laboratory standard, OT2: (r2 = 0.78, m = 1.05, and b = -2.20, P < 0.001), ADV: (m = 1.02, b = 24.1, r2 = 0.12, P = 0.133). The One Touch II Hospital accurately predicted amniotic fluid glucose at the bedside with excellent correlation including with laboratory standard glucose levels < 30 mg/dl. ADV and ELT proved too inaccurate for clinical use. Control samples were not affected by additives or time delay. These findings confirm that AFG determinations can be obtained rapidly with the OT2 meter at the bedside.

Obstetrical factors governing the etiopathogenesis of lambdoid synostosis.

Lambdoid synostosis results in skull deformities of varying degrees characterized by occipital flattening over the involved suture and other compensatory changes in skull shape. Such changes include contralateral occipital bossing, contralateral frontal flattening, ipsilateral frontal bossing, and ipsilateral anteroinferior displacement of the pinna (ear shearing). These deformities tend to worsen during the first year of life. The etiology has been attributed to genetic factors and primary disorders of bone growth, in addition to secondary effects of other diseases and modulators of the in utero environment. To determine causal factors in the development of lambdoid synostosis, the authors reviewed medical records of the mothers of 13 children with lambdoid synostosis who were treated at the University Medical Center of the State University of New York at Stony Brook. Pre- and perinatal events, prior obstetrical, gynecological, medical, social, and family histories were considered. Births of normal infants immediately prior to and just after the affected babies were born were selected as controls. There is a significant association between increased duration of the first stage of labor and the development of lambdoid synostosis. Furthermore, our results indicate that this condition has a predilection toward male infants, and may be associated with preterm labor.

Hemodynamic and hormonal responses to atrial distension in the ovine fetus.

OBJECTIVE: Our purpose was to evaluate the hemodynamic and endocrine responses to elevations of atrial pressure in fetal sheep. STUDY DESIGN: By use of a randomized block design, 10 ovine fetuses underwent pulmonary artery constriction proximal to the ductus arteriosus with and without propranolol pretreatment. RESULTS: Atrial pressure doubled (p < 0.05), whereas mean arterial pressure remained unchanged (p > 0.05), in response to pulmonary artery constriction in both groups. Atrial natriuretic peptide tripled (p < 0.01), arginine vasopressin tripled (p < 0.05), and plasma renin activity doubled (p < 0.05) in both the constriction and constriction plus propranolol groups. No changes in fetal hematocrit values were demonstrated in any group. CONCLUSIONS: The fetal sheep responds to increased atrial pressure with not only increased levels of atrial natriuretic peptide but also with arginine vasopressin and plasma renin activity over time. These changes occur in spite of increases in both atrial pressure and atrial natriuretic peptide. We speculate that the fetal heart may participate in redistribution of cardiac output by releasing atrial natriuretic peptide and augmenting secretion of arginine vasopressin and plasma renin activity.

Nitric oxide metabolites and preterm pregnancy complications.

OBJECTIVE: Intraamniotic infection may play a significant role in preterm labor and premature rupture of membranes. Synthesis of nitric oxide and its metabolites nitrite and nitrate purportedly are increased in infection. This project was designed to evaluate whether plasma or urine nitrate concentrations are increased in patients with either preterm labor or premature rupture of membranes in comparison with pregnant controls. STUDY DESIGN: A total of 42 patients between 24 and 35 weeks' gestation (20 with preterm labor; 14 with premature rupture of membranes, and 8 with premature rupture of membranes and contractions) and 35 additional patients without preterm labor or premature rupture of membranes (controls) had blood and urine collected for nitrate determination. Nitrate was reduced to nitrite and quantitated with the Griess reagent. RESULTS: The urine nitrate concentrations were significantly higher only in the preterm labor group compared with the control group (1.23 +/- 0.22 vs 0.67 +/- 0.05 mumol/mg creatinine, p < 0.05). The plasma nitrate level, however, was significantly higher in both the preterm labor and the premature rupture of membranes groups compared with the control group (52.47 +/- 10.11 and 40.05 +/- 5.38 mumol/L vs 16.29 +/- 2.89 mumol/L, p < 0.05). However, the concentrations of nitrate in the urine or plasma did not correlate with time from admission to delivery (p > 0.2). Finally, the presence of positive cervical or urine cultures, a clinical examination consistent with chorioamnionitis, or a maternal temperature > 100.4 degrees F was not associated with higher levels of nitrates in this small series of patients. CONCLUSION: Patients with preterm labor or premature rupture of membranes do have increased nitrate concentrations; however, this increased concentration is not predictive of impending delivery but may indicate that a subclinical infectious process is occurring.

Effect of atrial natriuretic factor on release of arginine vasopressin and renin in fetal lambs.

The purpose of this study was to determine the effect of increased plasma atrial natriuretic factor (ANF) concentrations on the arginine vasopressin (AVP) and renin response to arterial hypotension in fetal sheep. Lamb fetuses at 123-133 days of gestation were infused intravascularly with 0.9% NaCl and ANF at 25 ng.kg-1.min-1 (low dose) or NaCl and ANF at 250 ng.kg-1.min-1 (high dose) for 115 min. After 45 min, sodium nitroprusside was infused for 10 min to yield a 25% decrease in mean arterial blood pressure. ANF infusions resulted in plasma concentrations of 150-200 and 500-800 pg/ml in the low-dose and high-dose groups, respectively. In both the low-dose and high-dose ANF groups, AVP and renin concentrations increased in response to hypotension. In the low-dose ANF group, there was no difference in this response between ANF and control lambs. Compared with controls, a high dose of ANF resulted in an elevated basal level of AVP (1.6 +/- 0.04 vs. 12.3 +/- 6.7 pg/ml) and an 11-fold increase of AVP at 10 min of hypotension (12.2 +/- 5.6 vs. 134.9 +/- 36.1 pg/ml). Basal and stimulated renin concentrations were unchanged by the high-dose ANF infusion. This study demonstrates that in the fetal lamb, ANF concentrations of 500-800 pg/ml augment the basal and stimulated release of AVP but do not affect the renin response.

Sonographic estimation of fetal weight based on a model of fetal volume.

OBJECTIVES: To derive a formula for sonographic estimated fetal weight (EFW) based on a two-compartment model of fetal volume and to test it against two widely used formulas, especially at the extremes of fetal weight for which existing formulas are generally inaccurate. METHODS: We analyzed 865 consecutive sonograms that met the following inclusion criteria: singleton pregnancy, normal anatomy, delivery within 3 days of sonography, and measurements of biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). The weight of the fetal head was modeled to be proportional to HC3, and the weight of the trunk proportional to AC2 x FL. The proportionality constants were found by multiple linear regression on 380 sonograms performed in 1990 (the "derivation set"). The new formula was tested for accuracy of prediction of actual birth weight against the formulas of Hadlock et al and Shepard et al using 485 sonograms from 1991-1992 (the "validation set"). RESULTS: In the derivation set, the formula EFW = (0.23718 x AC2 x FL) + (0.03312 x HC3) was fit; the correlation with actual birth weight had an r value of 0.996. In the validation set, the new formula produced smaller systematic errors and smaller absolute errors than either the Hadlock or Shepard formula both overall and in fetal weight strata from less than 1000 g to over 4000 g. CONCLUSION: The new formula makes geometric sense and provides accurate estimates of fetal weight across a broad range of weights.

Effect of elevated atrial pressure on plasma renin activity in hypotensive fetal lambs.

In adults, renin secretion is stimulated by reductions in arterial pressure and inhibited by increases in atrial pressure. In the late gestation fetus, a fall in arterial pressure stimulates renin secretion, but it is unknown whether elevation of atrial pressure will alter such an increase. Therefore we studied the effect of elevated atrial pressure on renin secretion in the presence of nitroprusside-induced arterial hypotension. Thirteen fetal lambs at 127.9 +/- 0.9 days of gestation were prepared 5 days before study with inflatable pulmonary artery occluders and right atrial, vascular, and amniotic catheters. Each fetus underwent two protocols (hypotension and hypotension with occlusion) using a randomized block design. Nitroprusside reduced arterial pressure by 34% in both groups. Right atrial pressure during the course of hypotension was significantly higher in the occlusion group (F = 14.2, P = 0.001). Plasma renin activity increased similarly in both groups during hypotension (F = 6.0, P = 0.003). Elevated right atrial pressure did not alter hypotension-induced renin secretion in the fetus.