Preterm prediction study: comparison of the cervical score and Bishop score for prediction of spontaneous preterm delivery.

OBJECTIVE: To prospectively compare digital cervical score with Bishop score as a predictor of spontaneous preterm delivery before 35 weeks of gestation. METHODS: Data from a cohort of 2,916 singleton pregnancies enrolled in a multicenter preterm prediction study were available. Patients underwent digital cervical examinations at 22-24 and 26-29 weeks of gestation for calculation of Bishop score and cervical score. Relationships between Bishop score, cervical score, and spontaneous preterm delivery were assessed with multivariable logistic regression analysis, McNemar test, and receiver operating characteristic (ROC) curves to identify appropriate diagnostic thresholds and predictive capability. RESULTS: One hundred twenty-seven of 2,916 patients (4.4%) undergoing cervical examination at 22-24 weeks had a spontaneous preterm delivery before 35 weeks. Eighty-four of the 2,538 (3.3%) reexamined at 26-29 weeks also had spontaneous preterm delivery. Receiver operating characteristic curves indicated that optimal diagnostic thresholds for Bishop score were at least 4 at 22-24 weeks, at least 5 at 26-29 weeks, and less than 1.5 at both examinations for cervical score. At 22-24 weeks, areas under the ROC curve favored Bishop score. At 26-29 weeks, there was no significant difference in areas under the ROC curve; however, a cervical score less than 1.5 (sensitivity 35.7%, false positive rate 4.8%) was superior to a Bishop score of 5 or more (P<.001). CONCLUSION: Both cervical evaluations are associated with spontaneous preterm delivery in a singleton population; however, predictive capabilities for spontaneous preterm delivery were modest among women with low event prevalence. Although Bishop score performed better in the mid trimester, by 26-29 weeks a cervical score less than 1.5 was a better predictor of spontaneous preterm delivery before 35 weeks than a Bishop score of at least 5.

A vasopressin antagonist blocks the norepinephrine and epinephrine responses to hemorrhage in the fetus.

In 8 chronically cannulated fetal lambs between 119 and 127 days gestation the resting plasma norepinephrine concentration was 528 +/- 77 pg X ml-1 and the resting plasma epinephrine concentration 159 +/- 42 pg X ml-1. Hemorrhage of 20% of estimated blood volume at 2% per min produced a 2.1-fold increase in plasma norepinephrine levels and a 3.4-fold increase in plasma epinephrine levels when the animals were pretreated with an injection of saline (1 ml). Plasma catecholamine levels returned toward control values following return of the shed blood. In contrast, hemorrhage of these animals following pretreatment with an antagonist of the pressor effect of vasopressin did not cause an increase in fetal plasma catecholamine levels. Thus, vasopressin may mediate the sympathetic responses to volume depletion in the fetus.

In vivo evidence for increased adrenal sensitivity to adrenocorticotropin-(1-24) in the lamb fetus late in gestation.

Plasma concentrations of immunoreactive ACTH and cortisol were monitored daily in chronically cannulated sheep fetuses during the last 3 weeks of gestation. A prepartum increase in fetal plasma cortisol occurred without a concomitant rise in fetal plasma ACTH. When fetal lambs were injected with various doses of ACTH-(1-24) and the plasma cortisol responses were integrated over time, the resulting changes in the log dose-response curves indicate that fetal adrenal sensitivity increases late in gestation. Thus, the marked rise in fetal plasma cortisol before birth can be explained, at least in part, by an increase in fetal adrenal sensitivity to ACTH.

Subhourly variability of circulating third trimester maternal steroid concentrations as a source of sampling error.

Seven plasma samples from five normal third trimester pregnant women, drawn every 5 and 15 min at similar times on 2 days, 2 days apart, were measured in quadruplicate for estradiol (E2), estriol, progesterone, 16 alpha-hydroxyprogesterone, and 17 alpha-hydroxyprogesterone (17P). The mean of the 22 samples obtained from each subject for each steroid was used as a reference mean. Individual determinations were converted to percentages of the reference mean which was normalized to 0%. All pregnancies were uncomplicated, and all mean values were within the normal range for gestational age. Variability about the reference mean for single samples, however, range from a low of -80% to a high of 150%. The single sample, 95% confidence intervals for individual steroids pooled from the five subjects (110 determinations) range from +/- 36% (E2) to +/- 60% (17P). Mean percentage coefficients of variation between 5-min and 15-min sampling sequences were compared by analysis of variance. There is no significant difference between the mean percentage coefficients of variation of a 5-min as opposed to a 15-min sampling sequence for any of the hormones measured. The 95% confidence interval width around the reference mean is a function of the number of samples obtained. Because the 95% confidence interval width from 110 measurements decreases approximately as 1/ square root n with increasing sampling size, the decrement progressively diminishes. For E2, the least variable steroid, a one-sample 95% confidence interval width of +/- 36% decreases to approximately +/- 18% with four samples or approximately +/- 12% with nine samples. For 17P, the most variable steroid, a one-sample 95% confidence interval width of +/- 60% decreases to approximately +/- 30% with four samples or approximately +/- 20% with nine samples. Multiple sampling with plasma pooling is required for the accurate study of steroid concentrations in individual subjects in late pregnancy.

Race differences in infant mortality from endogenous causes: a population-based study in North Carolina.

This study examines the associations between race, birth weight, and mortality from endogenous causes for all singleton births born in 1984-1987 in a 20-county region of North Carolina. A more detailed analysis of preterm low birth weight infants examines these associations according to the proximate medical causes (medical etiology) of the preterm birth. Overall, black infants were found to have approximately twice the mortality risk of white infants. Most of the excess black mortality risk is explained by the larger proportion of black infants born at lower birth weights. The pattern of race differences in infant mortality by birth weight generally replicates the results of earlier studies, but the relative risk ratios within specific birth weight categories are smaller than previously reported. Among preterm low birth weight infants, the association between race and endogenous mortality differs within categories of medical etiology. The mortality risk is the same for black and white infants born preterm due to premature rupture of the membranes (PROM), lower for black infants born preterm due to medical problems, and higher for black infants born preterm due to idiopathic premature labor (IPL).

Total parenteral nutrition in pregnancy.

Total parenteral nutrition has been used infrequently during pregnancy. Because of the special nutritional needs and hormonal environment of the maternal-fetal unit, there is uncertainty as to the optimal composition and quantity of total parenteral nutrition therapy. In this report two important questions are examined: whether or not a protein replacement commonly used in total parenteral nutrition provides adequate levels of essential amino acids to fetus and mother, and whether or not the daily use of fat emulsion as part of total parenteral nutrition is associated with unwanted side effects. The authors' data suggest that certain adjustments have to be made in the quantity and composition of total parenteral nutrition constituents to provide the necessary nutritional requirements for metabolic and anabolic needs without increasing the overall risk for complications.

Sinusoidal fetal heart rate pattern associated with butorphanol administration.

One hundred nineteen fetal heart rate monitor tracings from term-pregnant patients in labor were reviewed by two independent observers to test the hypothesis that Stadol administration to mothers does not result in sinusoidal fetal heart rate pattern. There was agreement with regard to the interpretation of the tracings in 106 instances. Fifty-one patients received intravenous Stadol for narcotic analgesia. Seventy-five percent of these patients demonstrated a transient sinusoidal fetal heart rate pattern after Stadol administration. In a small number of patients, this pattern recurred either with or without additional Stadol treatment. In contrast, patients who did not receive Stadol therapy (N = 55) demonstrated a significantly lower incidence of sinusoidal fetal heart rate pattern (13%), the duration of which was significantly shorter than that seen in the former group. From these we conclude that Stadol therapy during labor is strongly associated with the appearance of sinusoidal fetal heart rate pattern. There were no short-term maternal or neonatal adverse sequelae. In the absence of other fetal heart rate signs suggestive of fetal distress, the presence of sinusoidal fetal heart rate pattern after Stadol administration does not indicate fetal hypoxia.

Vaginal pH: a marker of preterm premature rupture of the membranes.

Preterm premature rupture of the membranes (PROM) is a common predecessor of preterm or low birth weight (LBW) birth, yet the risk of preterm PROM is presently unpredictable. Numerous infectious organisms that change the normal vaginal milieu have been associated with preterm PROM. Because these organisms alter vaginal pH, the use of pH was evaluated as a potential marker for women at increased risk for preterm PROM. Among 115 women at high risk for an LBW birth, those with a mean vaginal pH above 4.5 had a threefold increased risk of preterm PROM as compared with those with a mean pH of 4.5 or lower. Vaginal pH may be a useful marker to predict a woman's risk for preterm PROM.

Late meconium passage in labor--a sign of fetal distress?

Although the passage early in labor of thick amniotic fluid heavily stained with meconium is recognized as an indication of potential fetal asphyxia, the significance of late passage of meconium-stained fluid in labor is less certain. One hundren twenty-eight patients with late passage of meconium in labor and 134 control patients were examined, using chi 2 and discriminant analysis, to determine if any relationships existed between fetal heart rate (FHR) patterns, late passage of meconium in labor, and neonatal morbidity. In the group with late meconium passage, adequate baseline FHR variability and nonperiodic accelerations were predictive of high Apgar scores, and repeated (over 20) variable decelerations were predictive of low Apgar scores. In the control group, none of the FHR patterns examined were predictive of Apgar score. Thus, the combination of late passage of meconium in labor with other intrapartum signs may indicate a fetus at risk for asphyxia when neither sign alone is predictive. The presence of late meconium passage demands close observation of the patient in labor, including assessment by electronic FHR monitoring.

The premature breech: trial of labor or cesarean section?

Sixty-six premature breech deliveries were studied retrospectively. Forty-eight patients were permitted a trial of labor, 47 of whom ultimately delivered vaginally. Eighteen patients underwent cesarean section as soon as possible after their arrival at the delivery suite. When Apgar scores, perinatal mortality rates, cord prolapse, and entrapment of the aftercoming head are considered, cesarean section is probably the safer course of management for the patient with a footling breech infant, especially when the infant weighs 1500 g or less. However, the data indicate that a trial of labor can be safely undertaken in the presence of a premature frank or complete breech presentation.

Efficacy of combined administration of magnesium sulfate and ritodrine in the treatment of premature labor.

Seventy-four patients in preterm labor at 20-35 weeks' gestation were randomly assigned to receive ritodrine (N = 36) or ritodrine plus magnesium sulfate treatment (N = 38) for tocolysis. Ten did not complete therapy and were excluded from analysis. Nineteen of 32 patients (59%) in the ritodrine plus magnesium sulfate group were successfully treated, compared with only 11 of 32 patients (34%) in the ritodrine-only group (P less than .05). Of the 21 patients who failed to respond to the initial ritodrine treatment, 16 received intravenous magnesium sulfate supplemental therapy; 75% of this group were treated successfully. The frequency of adverse maternal and fetal side effects did not differ between the treatment groups. In the combined group compared with the ritodrine group, the dose requirements for ritodrine therapy as well as the total duration of treatment for both ritodrine and magnesium sulfate were reduced significantly. We conclude that concurrent administration of ritodrine and magnesium sulfate is more efficacious than ritodrine alone and does not appear to increase the frequency of adverse side effects.

Amniotic fluid embolism after saline amnioinfusion: two cases and review of the literature.

BACKGROUND: Amnioinfusion is an intrapartum intervention with proven benefit in certain clinical situations. It is thought to be a safe treatment with few adverse effects. CASES: Two cases of fatal amniotic fluid (AF) embolism occurred in women who were treated during labor with a saline amnioinfusion. In both cases, amnioinfusion was administered after finding thick meconium staining of the AF. In addition to the amnioinfusion, common factors in these cases and three previously reported AF embolisms associated with amnioinfusion are the presence of rapid labor, meconium-stained fluid, or both. CONCLUSIONS: Amniotic fluid embolism is a rare cause of maternal morbidity and mortality. It is not known whether amnioinfusion increases the rate of its occurrence in laboring patients. No change in clinical practice is warranted on the basis of these reports; however, future reports must be examined so that any common factors can be identified.

The preterm prediction study: fetal fibronectin testing and spontaneous preterm birth. NICHD Maternal Fetal Medicine Units Network.

OBJECTIVE: To evaluate the presence of fetal fibronectin in the cervix and vagina as a screening test for spontaneous preterm birth. METHODS: Two thousand nine hundred twenty-nine women at ten centers were routinely screened every 2 weeks from 22-24 to 30 weeks for cervical and vaginal fetal fibronectin. A positive test was defined as a value equal to or greater than 50 ng/mL. The relation between a positive test at four gestational ages and spontaneous preterm birth at various intervals after the test was determined. RESULTS: In each testing period, 3-4% of the fetal fibronectin tests were positive. The correlation between cervical and vaginal fetal fibronectin at the same visit was always approximately 0.7 (P < .001), and that between cervical or vaginal fetal fibronectin in consecutive visits was between 0.17 and 0.25 (P < .001). The sensitivity of fetal fibronectin at 22-24 weeks to predict spontaneous preterm birth at less than 28 weeks was 0.63, and the relative risk for a positive versus negative test was 59. The specificity was always 96-98%, whereas the positive predictive value rose from 13% to 36% as the upper limit of the definition of preterm birth was increased from less than 28 to less than 37 weeks. The relative risk for spontaneous preterm birth after a positive fetal fibronectin test compared with a negative fetal fibronectin test varied substantially by testing period and by the definition of spontaneous preterm birth, but always remained greater than 4 and statistically significant. CONCLUSION: A positive cervical or vaginal fetal fibronectin test at 22-24 weeks predicted more than half of the spontaneous preterm births at less than 28 weeks (sensitivity 0.63). As the definition of spontaneous preterm birth was extended to include later gestational ages or when the fetal fibronectin test was performed later in pregnancy, the level of association between a positive fetal fibronectin test and spontaneous preterm birth, while remaining highly significant, tended to decrease. Although fetal fibronectin is an excellent test for predicting spontaneous preterm birth, we present no evidence that the use of this test will result in a reduction in spontaneous preterm birth.

Bupivacaine paracervical block. Effects on the fetus and neonate.

To evaluate effects on the fetus and neonate, 53 paracervical blocks were administered to 38 low-risk parturients using a controlled superficial injection of 0.25% bupivacaine. Continuous fetal heart rate monitoring revealed no instance of bradycardia or late deceleration pattern. Apgar scores, cord arterial and venous pH values, and neurobehavioral evaluations of the neonates were similar to those observed in other low-risk patients. The effectiveness of pain relief of the blocks was less than expected or reported by other authors. Although we observed no harmful effects on the fetus or neonate from the superficial paracervical injection of bupivacaine, we did not find this combination of drug and technique to give dependable, effective pain relief in labor.

Premature rupture of membranes: a prospective, randomized evaluation of steroids, latent phase, and expectant management.

A prospective, randomized study was conducted comparing the use of betamethasone and early delivery, early delivery alone, and expectant management in patients in the 28th to 34th week of pregnancy with premature rupture of the membranes (PROM). Tocolytic drugs were used to delay delivery until 24 hours had elapsed after the first dose of steroid or 24 to 48 hours of latent period had elapsed in the second group. There were no significant differences in maternal age, gestation at PROM, maximum maternal temperature, birth weights, maternal hospital days, respiratory distress, maternal sepsis, or delivery routes in the three groups. Comparisons with one other similar prospective, randomized study support the concept that expectant management offers less risk from tocolytic side effects.

A randomized trial of nurse intervention to reduce preterm and low birth weight births.

OBJECTIVE: To test the effect of telephone calls from registered nurses to low-income pregnant women on the rates of low birth weight (LBW) and preterm births. METHODS: A total of 1554 women receiving prenatal care in a public clinic who met study criteria and who consented were assigned randomly to intervention and control groups. Women in the intervention group received telephone calls from a registered nurse, one or two times weekly from 24 weeks' through 37 weeks' gestation. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated. RESULTS: Low birth weight rates were 10.9% in the intervention group and 14.0% in the control group (RR 0.75; 95% CI 0.55, 1.03; P = .072). For gestational age less than 37 weeks, rates were 9.7 in the intervention group and 11.0 in the control group (RR .87; 95% CI 0.62, 1.22; P = .415). In the subgroup of low-income black women 19 years of age and older, a statistically significant difference was found in preterm birth rates before 37 weeks (8.7% in the intervention group versus 15.4% in the controls [RR 0.56; 95% CI 0.38, 0.84; P = .004]). CONCLUSION: There was no difference in LBW or preterm births between intervention and control groups in the total sample. In a secondary analysis of black subjects 19 years of age and older, there was a significant difference in preterm birth rates.

A prospective study of insulin sensitivity and glucose metabolism in women using a continuous subdermal levonorgestrel implant system.

OBJECTIVE: Decreased insulin sensitivity and deterioration in oral glucose tolerance curves have been reported with oral contraceptive use, particularly with those containing levonorgestrel. However, the subdermal levonorgestrel systems release a lower dosage of steroid and avoid the first pass through the liver that occurs with oral administration. We hypothesized, therefore, that continuous subdermal levonorgestrel has no significant effect on insulin sensitivity and other indices of glucose metabolism. METHODS: Nine women desiring a subdermal hormonal contraceptive system were recruited for this longitudinal prospective study. Each subject underwent a 3-hour frequently sampled intravenous glucose tolerance test immediately before insertion and after 6 months of continuous use. Insulin sensitivity and glucose effectiveness were determined using a mathematical minimal modeling approach. Glucose clearance and fasting and peak levels of glucose and insulin were examined as well. The matched-pair data were analyzed using paired t tests. RESULTS: There was no significant change in insulin sensitivity, glucose effectiveness, glucose clearance, or fasting or peak insulin levels. Fasting glucose levels remained within a normal range. CONCLUSIONS: Subdermal levonorgestrel appears to have no significant effect on tissue insulin sensitivity or glucose metabolism after 6 months of continuous use.

Pregnancy alters diurnal variation of plasma glucose concentration.

Human pregnancy introduces a diurnal variation of fasting plasma glucose concentrations, with significantly lower values found after a daytime fast of eight hours compared with a night-time fast of the same duration. The diurnal variation of plasma glucose clearance, found in nonpregnant subjects, is not demonstrable during pregnancy. Insulin tolerance does not exhibit a circadian valuation but is substantially decreased during pregnancy.

The effect of a preterm birth prevention program in 17 rural and three urban counties in northwest North Carolina.

The results of a program of low birthweight prevention in 17 rural (20,727 births) and three urban counties (15,561 births) for calendar years 1985 and 1986 are described. Records for women in the program were matched with birth certificate data by computer. Rural and urban women in and out of the program were compared by race on the following risk factors: age less than 18 years, unmarried, education less than 12 years, Medicaid recipient, not WIC recipient, inadequate prenatal care, and previous fetal or live born death. Adjusting for these risk factors, logistic regression was used to estimate program effects on low birthweight (LBW), very low birthweight (VLBW), and preterm low birthweight (PLBW) among rural women. There was a statistically significant difference (p less than or equal to 0.01) favoring women in the program for very low birthweight and preterm low birthweight in white women, and low birthweight and preterm low birthweight in nonwhite women. The differences in rural areas exceed those in urban areas for all but one mean, very low birthweight births among white women.

Trisomy-18 and antepartal fetal distress.

Two cases are presented wherein cesarean section was performed because of evidence of intrauterine growth retardation and antepartal fetal distress. Both infants had the trisomy-18 syndrome. Attention is drawn to the fact that the combination of growth retardation and fetal distress sometimes heralds the presence of severe anomalies in the fetus, and it is suggested that cesarean section should not be performed before one attempts to rule out such life-threatening abnormalities.