The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network

OBJECTIVES

This study was undertaken to determine the relationship between fetal fibronectin, short cervix, bacterial vaginosis, other traditional risk factors, and spontaneous preterm birth.

METHODS

From 1992 through 1994, 2929 women were screened at the gestational age 22 to 24 weeks.

RESULTS

The odds ratios for spontaneous preterm birth were highest for fetal fibronectin, followed by a short cervix and history of preterm birth. These factors, as well as bacterial vaginosis, were more strongly associated with early than with late spontaneous preterm birth. Bacterial vaginosis was more common--and a stronger predictor of spontaneous preterm birth--in Black women, while body mass index less than 19.8 was a stronger predictor in non-Black women. This analysis suggests a pathway leading from Black race through bacterial vaginosis and fetal fibronectin to spontaneous preterm birth. Prior preterm birth is associated with spontaneous preterm birth through a short cervix.

CONCLUSIONS

Fetal fibronectin and a short cervix are stronger predictors of spontaneous preterm birth than traditional risk factors. Bacterial vaginosis was found more often in Black than in non-Black women and accounted for 40% of the attributable risk for spontaneous preterm birth at less than 32 weeks.

Determinants of zinc intake in low-income black and white pregnant women

A prospective study was conducted to evaluate and compare the determinants of dietary zinc intake in black and white low-income pregnant women. The study population consisted of 1298 low-income women (70% Black, 30% White) who received prenatal care at University Hospital at the University of Alabama in Birmingham from 1985 to 1989. Various maternal characteristics were evaluated at the first prenatal visit. Two 24 h recalls were obtained at 18 and 30 wk of gestation to calculate the intakes of dietary zinc and other nutrients. Student's t test, chi2, Pearson correlation coefficients, and multiple regression analyses were used to compare and evaluate the determinants of zinc and other nutrient intakes in Black and White subjects. The mean prepregnancy body mass index and the mean intake of zinc, energy, and all the other nutrients except calcium were significantly higher in Black than in White subjects. There was a significant correlation between zinc and energy intake (r = 0.69, p = 0.001). Age, marital status, parity, socioeconomic status, smoking, and alcohol intake were not significant predictors of zinc or other nutrient intakes. After adjusting for energy intake, race was the only significant predictor of dietary zinc intake. Race and energy intake explained 24% of the variation in zinc intake. Results of this study indicate that after adjusting for other covariates, race and energy intakes are the only predictors of zinc intake in low-income pregnant women.

Plasma and erythrocyte zinc concentrations and their relationship to dietary zinc intake and zinc supplementation during pregnancy in low-income African-American women

OBJECTIVE

To evaluate the effects of usual dietary intake of zinc and of zinc supplementation during pregnancy on plasma and erythrocyte zinc concentrations.

DESIGN

A randomized, double-blind, placebo-controlled trial.

SUBJECTS

Low-income African-American women (n = 580) assigned randomly to groups at 19 weeks of gestation.

INTERVENTION

A daily dose of zinc (25 mg) or a placebo until delivery.

MAIN OUTCOME MEASURES

Plasma, erythrocyte, and dietary zinc levels.

STATISTICAL ANALYSES

Multiple regression and repeated measures analysis of variance.

RESULTS

In both the placebo and the supplemented groups, when all subjects were grouped by usual dietary zinc intake above or below the median (12 mg/day), results were the same: Women with high dietary zinc intake had higher erythrocyte zinc levels at the time of randomization and at all subsequent measurements during pregnancy than those who had low dietary zinc intake (P < or = .06; difference not significant for zinc-supplemented group); no difference was observed for plasma zinc levels. On the other hand, when the subjects were stratified at the median by total daily zinc intake (usual dietary zinc + 25 mg zinc supplement) during pregnancy, a significant difference in plasma zinc levels (P < .005) was found between women with high total zinc intake (mean = 38 mg/day) and low total intake (mean = 13 mg/day) at 26, 32, and 38 weeks of gestation; however, no such differences were found in erythrocyte zinc levels.

APPLICATIONS

These results should help dietitians and other health professionals better understand the expected changes in plasma and erythrocyte zinc levels during pregnancy, and the relationship between dietary and supplemental zinc and zinc nutriture.

Plasma alkaline phosphatase and pregnancy outcome

The objective was to determine the relationship between plasma alkaline phosphatase (AP) activity and birthweight (BWT) and preterm delivery (PTD). Five hundred eighty African-American women had plasma AP activities measured at various gestational ages (GA) with the results compared to a number of pregnancy outcomes. Plasma AP activity rose linearly during pregnancy from a mean of 39 U/L at 19 weeks to 130 U/L at delivery. In individual women, AP activities were consistently high or low as confirmed by correlation coefficients in adjacent time periods ranging from 0.63 to 0.87. AP at 19 weeks was not significantly associated with any outcome measure. However, at 26 weeks, AP in the highest quartile was associated with a 15.0% incidence of PTD < 37 weeks compared to 6.8% in the lower three quartiles (P = .004). For PTD < or = 32 weeks, the difference of PTD was 6.8 vs. 1.6% (P < .003). When women in the highest quartile of increase in AP from 19 to 26 weeks were compared to those in the lower quartiles, the rate of PTD < 37 weeks was 15.2 vs. 6.4% (P = .002), and the rate of PTD < or = 32 weeks was 6.1 vs. 1.7%, (P = .01). The mean BWT for the highest vs. the lower three quartiles in rate of increase was 3,058 vs. 3,288 g (P = .0005) and the mean GA was 38.1 vs. 39.2 weeks (P = .0001). Regression analyses adjusting for multiple confounders confirmed the association between high AP at 26 weeks and PTD < 37 weeks [OR (95% C.I.), 2.4 (1.2-4.8)] and PTD < or = 32 weeks [OR (95% C.I.), 3.7 (1.2-11.7)]. Similar results were found among women with a large increase in AP between 19 and 26 weeks. From these results we conclude that high or increasing AP activity at 26 weeks, but not 19 weeks, was significantly associated with subsequent PTD and a lower BWT.

The relationship between maternal characteristics and fetal and neonatal anthropometric measurements in women delivering at term: a summary

BACKGROUND

We wanted to determine the relationship between a number of maternal characteristics and various fetal and neonatal anthropometric measurements determined by ultrasound and at birth.

METHODS

A total of 1205 term singleton maternal-infant pairs were studied. Various ultrasound measurements obtained at 18, 24, 30 and 36 weeks' gestation and neonatal anthropometric measurements obtained at birth were studied in relationship to various maternal characteristics using univariate and multivariate techniques.

RESULTS

Black race, female sex, cigarette smoking, drug use, having a previous low birthweight infant, maternal hypertension and being short or thin or failing to gain weight each resulted in a birthweight decrease of 100 to 300 g. The effect of each of these characteristics on each ultrasound measurement, the timing of the effect, and its ultimate effect on neonatal anthropometric measurements are described.

CONCLUSION

The data presented in this paper provide a more complete understanding of the relationship between maternal characteristics, infant sex, and various fetal ultrasound and neonatal measurements.

The preterm prediction study: maternal stress is associated with spontaneous preterm birth at less than thirty-five weeks' gestation. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network

OBJECTIVE

Our purpose was to determine whether various measures of poor psychosocial status in pregnancy are associated with spontaneous preterm birth, fetal growth restriction, or low birth weight.

STUDY DESIGN

Anxiety, stress, self-esteem, mastery, and depression were assessed at 25 to 29 weeks in 2593 gravid women by use of a 28-item Likert scale. Scores for each psychosocial subscale were determined, and an overall psychosocial score was calculated. Scores were divided into quartiles, and the lowest quartile scores were used to define poor psychosocial status. The percent spontaneous preterm birth, low birth weight, and fetal growth restriction in women with low and high psychosocial scores were compared. Logistic regression analyses provided the odds ratios and 95% confidence intervals.

RESULTS

Analyses revealed that stress was significantly associated with spontaneous preterm birth and with low birth weight with odds ratios of 1.16, p = 0.003, and 1.08, p = 0.02, respectively, for each point on the scale. A low score on the combined scale or on any subscale other than stress did not predict spontaneous preterm birth, fetal growth restriction, or low birth weight. After multivariate adjustment was performed for psychosocial status, substance use, and demographic traits, black race was the only variable significantly associated with spontaneous preterm birth, fetal growth restriction, and low birth weight; stress and low education were associated with spontaneous preterm birth and low birth weight.

CONCLUSION

Stress was associated with spontaneous preterm birth and low birth weight even after adjustment for maternal demographic and behavioral characteristics. Black race continues to be a significant predictor of spontaneous preterm birth, fetal growth restriction, and low birth weight even after adjustment for stress, substance use, and other demographic factors.

Plasma ferritin and pregnancy outcome

OBJECTIVE

Plasma ferritin is considered the best measure of total body iron, with low levels diagnostic of iron deficiency. High levels have been associated with inflammation and infection. We determined the relationship between plasma ferritin, birth weight, and preterm delivery.

STUDY DESIGN

Plasma ferritin and hematocrit values were measured at 19, 26, and 36 weeks' gestational age and correlated with birth weight and preterm delivery (< or = 32 and < 37 weeks) in 580 indigent black women.

RESULTS

Hematocrit levels measured at any gestational age did not correlate significantly with birth weight or preterm delivery. Regardless of the gestational age of sampling, ferritin levels in the lowest quartile did not correlate significantly with subsequent preterm delivery. However, at 26 weeks, compared with the three lower quartiles, ferritin levels in the highest quartile were significantly associated with preterm delivery < or = 32 weeks, 6.5% versus 2.3% (p = 0.02), with preterm delivery < 37 weeks, 14% versus 8% (p = 0.04), and with birth weight < 1500 gm, 6.5% versus 2.0% (p = 0.01). Plasma ferritin levels in the highest quartile at 19, 26, and 36 weeks were associated with birth weight < or = 2500 gm, 14% versus 8% (p = 0.03), 12% versus 7% (p = 0.05), and 10% versus 2% (p = 0.0001), respectively, compared with the lower quartiles. Ferritin levels in the highest quartile were always associated with a lower mean birth weight than were those in the lower three quartiles: 19 weeks, 2999 gm versus 3225 gm, (p = 0.002); 26 weeks, 3065 gm versus 3257 gm, (p = 0.005); and 36 weeks, 3182 gm versus 3323 gm, (p = 0.009). Regression analyses controlling for multiple potential confounders confirmed that at 26 weeks ferritin levels in the highest quartile had an odds ratio and 95% confidence interval for preterm birth < 37 weeks of 2.0 (1.1 to 3.8), preterm delivery < or = 32 weeks of 2.7 (0.99 to 7.6), birth weight < or = 1500 gm of 3.9 (1.2 to 12.2), and birth weight < or = 2500 gm of 2.0 (1.0 to 4.0) compared with the three lower ferritin quartiles.

CONCLUSION

High, but not low, plasma ferritin levels, especially at 26 weeks, were strongly associated with subsequent preterm delivery and birth weight.

Factors influencing plasma zinc levels in low-income pregnant women

Plasma zinc (Zn) concentrations were measured in 4376 indigent women (86% African-American), at at mean (+/- SD) gestational age of 15 (+/- 7.8) wk to determine the relationship between various maternal characteristics and plasma Zn levels during pregnancy. Mean Plasma An levels were lower in African-American women than in Caucasian women, in multiparous women than in primiparous women, and in women with body weight > 69.9 kg than in those with body weight < or = 69.9 kg (p < or = 0.001 for each comparison). There were no significant differences related to maternal age, marital status, education, or smoking habit. Multiple regression analysis, including maternal prepregnancy weight, race, age, parity, smoking habit, education, and marital status indicated that race, parity, and pregnancy weight were significantly associated with maternal plasma Zn levels, adjusted for gestational age. Maternal race was the best predictor of plasma Zn concentrations among the population of pregnant women studied A significant proportion of variance in maternal plasma Zn levels. remained unexplained after taking into account various maternal characteristics. The reasons for lower plasma Zn levels in African-American women, compared to Caucasian women, during pregnancy are unknown.

The preterm prediction study: a clinical risk assessment system

OBJECTIVE

Our aims were to develop a risk assessment system for the prediction of spontaneous preterm delivery using clinical information available at 23 to 24 weeks' gestation and to determine the predictive value of such a system.

STUDY DESIGN

A total of 2929 women were evaluated between 23 and 24 weeks' gestation at 10 centers. Demographic factors, socioeconomic status, home and work environment, drug and alcohol use, and medical history were evaluated. Information regarding symptoms, cultures, and treatments in the current pregnancy were ascertained. Anthropomorphic and cervical examinations were performed. Univariate analysis and multivariate logistic regression were performed in a random selection, constituting 85% of the study population. The derived risk assessment system was applied to the remaining 15% of the population to evaluate its validity.

RESULTS

A total of 10.4% of women were delivered of preterm infants. The multivariate models for spontaneous preterm delivery were highly associated with spontaneous preterm delivery (p < 0.0001). A low body mass index (<19.8) and increasing Bishop scores were significantly associated with spontaneous preterm delivery in nulliparous and multiparous women. Black race, poor social environment, and work during pregnancy were associated with increased risk for nulliparous women. Prior obstetric outcome overshadowed socioeconomic risk factors in multiparous women with a twofold increase in the odds of spontaneous preterm delivery for each prior spontaneous preterm delivery. Current pregnancy symptoms, including vaginal bleeding, symptomatic contractions within 2 weeks, and acute or chronic lung disease were variably associated with spontaneous preterm delivery in nulliparous and multiparous women. When the system was applied to the remainder of the population, women defined to be at high risk for spontaneous preterm delivery (> or = 20% risk) carried a 3.8-fold (nulliparous women) and 3.3-fold (multiparous women) higher risk of spontaneous preterm delivery than those predicted to be at low risk. However, the risk assessment system identified a minority of women who had spontaneous preterm deliveries. The sensitivities were 24.2% and 18.2% and positive predictive values were 28.6% and 33.3%, respectively, for nulliparous and multiparous women.

CONCLUSIONS

Although it is possible to develop a graded risk assessment system that includes factors that are highly associated with spontaneous preterm delivery in nulliparous and multiparous women, such a system does not identify most women who subsequently have a spontaneous preterm delivery. This system has investigational value as the basis for evaluating new technologies designed to identify at-risk subpopulations.

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.

The length of the cervix and the risk of spontaneous premature delivery. National Institute of Child Health and Human Development Maternal Fetal Medicine Unit Network

BACKGROUND

The role of the cervix in the pathogenesis of premature delivery is controversial. In a prospective, multicenter study of pregnant women, we used vaginal ultrasonography to measure the length of the cervix; we also documented the incidence of spontaneous delivery before 35 weeks' gestation.

METHODS

At 10 university-affiliated prenatal clinics, we performed vaginal ultrasonography at approximately 24 and 28 weeks of gestation in women with singleton pregnancies. We then assessed the relation between the length of the cervix and the risk of spontaneous preterm delivery.

RESULTS

We examined 2915 women at approximately 24 weeks of gestation and 2531 of these women again at approximately 28 weeks. Spontaneous preterm delivery (at less than 35 weeks) occurred in 126 of the women (4.3 percent) examined at 24 weeks. The length of the cervix was normally distributed at 24 and 28 weeks (mean [+/- SD], 35.2 +/- 8.3 mm and 33.7 +/- 8.5 mm, respectively). The relative risk of preterm delivery increased as the length of the cervix decreased. When women with shorter cervixes at 24 weeks were compared with women with values above the 75th percentile, the relative risks of preterm delivery among the women with shorter cervixes were as follows: 1.98 for cervical lengths at or below the 75th percentile (40 mm), 2.35 for lengths at or below the 50th percentile (35 mm), 3.79 for lengths at or below the 25th percentile (30 mm), 6.19 for lengths at or below the 10th percentile (26 mm), 9.49 for lengths at or below the 5th percentile (22 mm), and 13.99 for lengths at or below the 1st percentile (13 mm) (P < 0.001 for values at or below the 50th percentile; P = 0.008 for values at or below the 75th percentile). For the lengths measured at 28 weeks, the corresponding relative risks were 2.80, 3.52, 5.39, 9.57, 13.88, and 24.94 (P < 0.001 for values at or below the 50th percentile; P = 0.003 for values at the 75th percentile).

CONCLUSIONS

The risk of spontaneous preterm delivery is increased in women who are found to have a short cervix by vaginal ultrasonography during pregnancy.

Reduced incidence of preterm delivery with metronidazole and erythromycin in women with bacterial vaginosis

BACKGROUND

Pregnant women with bacterial vaginosis may be at increased risk for preterm delivery. We investigated whether treatment with metronidazole and erythromycin during the second trimester would lower the incidence of delivery before 37 weeks' gestation.

METHODS

In 624 pregnant women at risk for delivering prematurely, vaginal and cervical cultures and other laboratory tests for bacterial vaginosis were performed at a mean of 22.9 weeks' gestation. We then performed a 2:1 double-blind randomization to treatment with metronidazole and erythromycin (433 women) or placebo (191 women). After treatment, the vaginal and cervical tests were repeated and a second course of treatment was given to women who had bacterial vaginosis at that time (a mean of 27.6 weeks' gestation).

RESULTS

A total of 178 women (29 percent) delivered infants at less than 37 weeks' gestation. Eight women were lost to follow-up. In the remaining population, 110 of the 426 women assigned to metronidazole and erythromycin (26 percent) delivered prematurely, as compared with 68 of the 190 assigned to placebo (36 percent, P = 0.01). However, the association between the study treatment and lower rates of prematurity was observed only among the 258 women who had bacterial vaginosis (rate of preterm delivery, 31 percent with treatment vs. 49 percent with placebo; P = 0.006). Of the 358 women who did not have bacterial vaginosis when initially examined, 22 percent of those assigned to metronidazole and erythromycin and 25 percent of those assigned to placebo delivered prematurely (P = 0.55). The lower rate of preterm delivery among the women with bacterial vaginosis who were assigned to the study treatment was observed both in women at risk because of previous preterm delivery (preterm delivery in the treatment group, 39 percent; and in the placebo group, 57 percent; P = 0.02) and in women who weighed less than 50 kg before pregnancy (preterm delivery in the treatment group, 14 percent; and in the placebo group, 33 percent; P = 0.04).

CONCLUSIONS

Treatment with metronidazole and erythromycin reduced rates of premature delivery in women with bacterial vaginosis and an increased risk for preterm delivery.

The effect of zinc supplementation on pregnancy outcome

OBJECTIVE

To evaluate whether zinc supplementation during pregnancy is associated with an increase in birth weight.

DESIGN

A randomized double-blind placebo-controlled trial.

SETTING

Outpatient clinic and delivery service at the University of Alabama at Birmingham.

PATIENTS

Five hundred eighty medically indigent but otherwise healthy African-American pregnant women with plasma zinc levels below the median at enrollment in prenatal care, randomized at 19 weeks' gestational age. Women were subdivided by the population median body mass index of 26 kg/m2 into two groups for additional analyses.

INTERVENTION

Women who were taking a non-zinc-containing prenatal multivitamin/mineral tablet were randomized to receive either a daily dose of 25 mg of zinc or a placebo until delivery.

MAIN OUTCOME MEASURES

Birth weight, gestational age at birth, and head circumference at birth.

RESULTS

In all women, infants in the zinc supplement group had a significantly greater birth weight (126 g, P = .03) and head circumference (0.4 cm, P = .02) than infants in the placebo group. In women with a body mass index less than 26 kg/m2, zinc supplementation was associated with a 248-g higher infant birth weight (P = .005) and a 0.7-cm larger infant head circumference (P = .007). Plasma zinc concentrations were significantly higher in the zinc supplement group.

CONCLUSIONS

Daily zinc supplementation in women with relatively low plasma zinc concentrations in early pregnancy is associated with greater infant birth weights and head circumferences, with the effect occurring predominantly in women with a body mass index less than 26 kg/m2.

Maternal serum thromboxane B2 reduction versus pregnancy outcome in a low-dose aspirin trial

OBJECTIVE

Our purpose was to determine whether in a low-dose aspirin trial a longitudinal decrease in maternal serum thromboxane B2 is associated with improvement in pregnancy outcomes.

STUDY DESIGN

A total of 606 healthy nulliparous women with singleton gestations were randomized at 24 weeks to either 60 mg of aspirin or a placebo. Maternal serum thromboxane B2 was measured at randomization, at 29 to 31 weeks, at 34 to 36 weeks, and at delivery. After delivery, and without knowledge of patient outcome or group assignment, patients were categorized as having had either a longitudinal twofold or greater (> or = 50%) or less than twofold reduction (< 50%) in thromboxane B2 from baseline levels at randomization.

RESULTS

Of 606 entrants, 92% had sufficient thromboxane B2 determinations to allow categorization. Whether patients were assigned to aspirin or placebo, birth weight was significantly greater in women who had a twofold or greater reduction in maternal serum thromboxane B2 levels. When the aspirin and placebo groups were combined, women with a twofold or greater reduction in thromboxane B2 levels had less preeclampsia, 1.9% (6/314) versus 5.7% (14/244) (p = 0.016), less preterm delivery (5.7% vs 10.7%, p = 0.032), fewer small-for-gestational-age newborns, 9 of 314 (2.95) versus 17 of 244 (7%) (p = 0.023), and a higher mean birth weight, 3314 gm versus 3121 gm (p = 0.0001).

CONCLUSION

Women with a twofold or greater longitudinal reduction in maternal serum thromboxane B2 had less preeclampsia and prematurity, fewer small-for-gestational-age newborns, and higher birth weights than women with less than a twofold reduction.

The relationship of maternal attitude toward weight gain to weight gain during pregnancy and low birth weight

OBJECTIVE

To evaluate the relationships between maternal attitude toward weight gain, actual weight gain, and infant birth weight.

METHODS

Maternal attitude toward weight gain during pregnancy was assessed in 1000 women, using an 18-item questionnaire administered at a mean of 20 weeks' gestation. Composite scores were compared with pregnancy weight gain, maternal body mass index (BMI), and infant birth weight.

RESULTS

In the total population, the attitude score was not significantly related to pregnancy weight gain (r = -0.05, P = .08) and was negatively associated with birth weight (r = -0.09, P < .004). Maternal body size as measured by BMI was strongly associated with both weight gain and birth weight. Obese women (BMI greater than 26.6) tended to have negative attitudes and had the lowest mean weight gain (10.2 kg), but had the heaviest babies (3400 g). Thin women (BMI less than 19.6) had significantly higher attitude scores and a higher mean weight gain (14.1 kg) than did obese women. A significantly larger proportion of thin women achieved recommended gains when compared with larger women, but had the lightest babies (3114 g). Within the group of thin women, after adjustment for smoking, race, and gestational age at delivery, attitude scores were not significantly associated with either weight gain or birth weight.

CONCLUSION

Maternal attitude regarding weight gain is strongly influenced by pre-pregnancy body size; thin women tend to have positive attitudes and obese women tend to have negative attitudes about weight gain. Within BMI groups, a positive attitude does not predict appropriate weight gain or birth weight. These findings may explain in part why nutritional counseling programs tend to be associated with only minimal increases in birth weight.

The origin and outcome of preterm twin pregnancies

OBJECTIVE

To define the etiology of preterm twin births and determine the contribution of twin births to preterm birth and related morbidity and mortality.

METHODS

The March of Dimes Multicenter Prematurity and Prevention Study included a total of 33,873 women who delivered between 1982-1986, 432 (1.3%) of which delivered twins. Women were classified by reason for preterm birth and ethnicity. Neonates were classified as to stillbirth, neonatal death, and various short-term morbidities. A second data set from one center consisted of infants who weighed 1000 g or less, were born between 1979-1991, and survived to 1 year of age (n = 386, 15% twins); this was used to determine if twins and singletons born at comparable gestational ages have a similar risk for major developmental handicaps.

RESULTS

Of the deliveries in the data set, 54% of twins were preterm compared with 9.6% among singletons. Of those born preterm, twins were born at a significantly earlier gestational age than were singletons. Only 2.6% of all neonates born were twins, but they represented 12.2% of all preterm infants, 15.4% of all neonatal deaths, and 9.5% of all fetal deaths. Spontaneous labor accounted for 54% of twin births, premature rupture of membranes accounted for 22%, and indicated deliveries accounted for 23%. Of the indicated preterm births in twins, 44% were due to maternal hypertension, 33% to fetal distress or fetal growth restriction, 9% to placental abruption, and 7% to fetal death. Comparing infants of similar gestational age, twins weighed less, but had a mortality equivalent to that of singletons after 29 weeks. Between 26-28 weeks' gestation, the risk of mortality for twins versus singletons was 1.6 (95% confidence interval 1.1-2.5). Preterm twins did not have significantly more respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, or other short-term morbidity than did preterm singletons. Twins who weighed 500-1000 g and survived to 1 year had a 25% rate of major developmental handicaps. However, when gestational age was controlled, the rate of major handicaps was not higher in twins than in singletons.

CONCLUSIONS

Twins accounted for a disproportional amount of preterm birth and associated morbidity and mortality. Also, when preterm twins were compared with preterm singletons and corrected for their gestational ages, the rates of morbidity were similar. Preterm twins weighing less than 1000 g did not have an increased prevalence of major handicaps at 1 year of age compared with preterm singletons.

Cervical examination and tocodynamometry at 28 weeks' gestation: prediction of spontaneous preterm birth

OBJECTIVE

We determined the value of cervical examination and tocodynamometry in identifying nulliparous women at risk for spontaneous preterm delivery.

STUDY DESIGN

At 27.5 +/- 0.8 weeks' gestation 589 women underwent 30 minutes of tocodynamometry, and 570 of these had a cervical examination. Positive findings on these examinations were compared to the rate of spontaneous preterm delivery, defined as those deliveries following the onset of spontaneous labor or premature rupture of membranes.

RESULTS

The two best predictors of spontaneous preterm birth were two or more contractions in 30 minutes and the presence of a soft or medium consistency on cervical examination. As the contractions increased from zero to four or more, the rate of spontaneous preterm delivery rose from 4.2% to 18.2%.

CONCLUSION

In nulliparous women at 28 weeks' gestation, uterine contractions and several components of the cervical examination predicted spontaneous preterm birth.

Risk factors for fetal death in white, black, and Hispanic women. Collaborative Group on Preterm Birth Prevention

OBJECTIVE

To document the relation between stillbirth and various demographic, obstetric, and medical risk factors.

METHODS

We analyzed the risk factors and medical origins of 403 stillbirths. The population studied included 34,350 births occurring during the March of Dimes Preterm Birth Prevention Trial. All births occurring in five perinatal centers from 1982-1986 were included in the analysis. Stillbirth was defined as those infants born at 20 weeks' gestation or later whose Apgar score was 0 at 1 and 5 minutes.

RESULTS

Stillbirth occurred in 1.2% of all births. Fifty-one percent occurred before 28 weeks and only 18% were at term. Blacks had a greater risk of stillbirth when compared to other women. Prior preterm delivery yielded nearly a two-fold increase in the risk of stillbirth. Preeclampsia, chronic hypertension, and class A or class B-R diabetes were not associated with an increased risk of stillbirth. Other medical factors (hemoglobinopathies, Rh sensitization) resulted in a greater than sixfold increase in the rate of stillbirth, and congenital anomalies resulted in a fivefold increase. Abruption was associated with a 12-fold increase in the risk of stillbirth; nearly 14% of all stillbirths were associated with abruption.

CONCLUSION

Eighty-two percent of all stillbirths occurred before term, and more than 50% occurred before 28 weeks. The majority of stillbirths were not explained by medical complications, but instead were often associated with other risk factors related to preterm birth. Further investigations are needed to understand the complex etiology of stillbirth.

The relationship between maternal skinfold thickness, smoking and birthweight in black and white women

A prospective study was conducted in a sample of 1491 multiparous women to ascertain whether the relationship between maternal tricep skinfold thickness and infant birthweight is modified by smoking status and whether the relationship is different in white and black infants. Maternal tricep skinfold thickness measured at midpregnancy was a significant predictor of infant birthweight in both white and black infants after adjusting for gestational age at birth, maternal height, maternal age, parity, alcohol consumption and sex of the infant. However, maternal tricep skinfold thickness was a better predictor of birthweight in smokers compared with nonsmokers. Both white and black women with tricep skinfold thickness below the sample mean had lower infant birthweight than women with tricep skinfold at or above the mean, after adjusting for gestational age at birth, but the difference was greater in smokers (198 g for white and 221 g for black infants) than in nonsmokers (124 g for white and 221 g for black infants) than in nonsmokers maternal subcutaneous fat measured by tricep skinfold thickness has a greater effect on infant birthweight in smokers compared with nonsmokers, with similar effects in white and black infants.

The predictive value of umbilical artery Doppler studies for preeclampsia or fetal growth retardation in a preeclampsia prevention trial

OBJECTIVE

To determine the clinical utility of longitudinal Doppler umbilical artery systolic-diastolic ratios (S/D) to predict the occurrence of either preeclampsia or fetal growth retardation (FGR) in a low-risk population.

METHODS

Healthy nulliparas with singleton gestations were enrolled in a double-blind trial of low-dose (60 mg) aspirin for preeclampsia prevention. Treatment was initiated at 24 weeks and continued until delivery. Continuous-wave Doppler studies were scheduled before assignment to treatment and at 27-31, 32-36, and 37-42 weeks. Preeclampsia was defined as a persistent diastolic blood pressure of at least 90 mmHg with proteinuria, and FGR was defined as birth weight below the tenth percentile. Doppler values were considered abnormal if they exceeded the 90th percentile for the gestational age range in the study population. Summary predictive values were computed for the abnormal S/D at each gestational age interval. To assess the potential effect of the administration of low-dose aspirin, logistic regression was used to model the relation between the Doppler indices, aspirin use, and these abnormal pregnancy outcomes.

RESULTS

A total of 1665 Doppler examinations were performed on 565 women. Forty-four fetuses developed FGR and 21 women were diagnosed with preeclampsia. The positive predictive values of an abnormal S/D for the subsequent development of FGR were 13-17% across the gestational age ranges studied, and the positive predictive values for preeclampsia were 0-5%. Aspirin treatment did not affect the relation between the Doppler indices and these outcomes in the logistic regression model.

CONCLUSION

Elevated umbilical artery S/D is not a clinically useful predictor of either FGR or preeclampsia in a low-risk population.

The effect of corticosteroid therapy in the very premature infant. March of Dimes Multicenter Study Group

OBJECTIVE

Our purpose was to determine the efficacy of maternal corticosteroid therapy between 26 and 31 weeks' gestation.

STUDY DESIGN

The data in this study were derived from 32,658 women who participated in the March of Dimes-sponsored multicenter prematurity prevention program. Of the 432 women who were delivered at 26 to 31 weeks, 67 received betamethasone before delivery and 365 did not. The frequency and relative risks of adverse outcomes, including respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, and neonatal death were compared for each of two gestational age periods by means of univariate and multivariate techniques.

RESULTS

When betamethasone was administered > or = 2 days before delivery (n = 45), there was a lower incidence of respiratory distress syndrome in both the 26 to 28 week group (53.9% vs 86.5%, p = 0.008) and the 29 to 31 week group (25.0% vs 59.1%, p = 0.0003). The rate of intraventricular hemorrhage was less in the betamethasone group at 26 to 28 weeks (15.4% vs 32.3%, p = 0.17), but the difference reached statistical significance only at 29 to 31 weeks (3.1% vs 16.5%, p = 0.029). Neonatal death occurred significantly less often in infants who were delivered at 26 to 28 weeks when their mothers received betamethasone compared with infants of the same gestational age whose mothers did not receive betamethasone treatment (0% vs 34.6%, p = 0.01). In a regression analysis of infants born between 26 and 31 weeks in which birth weight, gestational age, race, infant sex, and tocolytic use were controlled, the odds ratio for respiratory distress syndrome associated with betamethasone use was 0.20 (0.10, 0.42), for intraventricular hemorrhage 0.26 (0.08, 0.90), and for neonatal death 0.14 (0.02, 1.09). Insufficient numbers of women were given betamethasone before 26 weeks for analysis.

CONCLUSION

Betamethasone appears to significantly reduce neonatal death and the morbidity between 26 and 31 weeks' gestation.

Are pill counts valid measures of compliance in clinical obstetric trials?

We compared pill counts with a biochemical measure of compliance in 283 women who participated in a randomized double-blind trial that evaluated the efficacy of low-dose aspirin in the prevention of preeclampsia. Subjects whose pill counts indicated a usage > 100% were less compliant than women with lower pill counts.

The effect of low-dose aspirin on fetal urine output and amniotic fluid volume

OBJECTIVE

Patients given prostaglandin synthetase inhibitors in doses sufficient to inhibit labor are at risk for developing oligohydramnios (possibly related to a reduction in fetal urine output). We sought to ascertain whether the fetuses of women who received 60 mg of aspirin daily had a lower urine output than those whose mothers were given a placebo.

STUDY DESIGN

Nulliparous women with singleton gestations in a double-blind preeclampsia prevention trial were randomly selected at 24 weeks' gestation to receive either 60 mg of aspirin daily or a placebo. Urine output was assessed in 59 fetuses (aspirin 32, placebo 27) by serial ultrasonographic measurement of their bladder volume (volume = 4/3 pi r3). Biochemical evidence of aspirin compliance was defined as an 80% reduction in maternal serum thromboxane B2 levels when comparing values obtained at randomization with those at 34 to 36 weeks' gestation.

RESULTS

Visual assessment of amniotic fluid volume was similar in both groups. Four-quadrant amniotic fluid indexes also were similar (13.5 cm in aspirin group vs 12.2 cm in placebo group, p = 0.15). Mean fetal urine outputs were similar in the aspirin (57.7 ml/hr) and placebo (55.1 ml/hr) groups (p = 0.71). Moreover, the 23 women with a fourfold thromboxane B2 reduction had a higher mean fetal urine output (63.5 vs 51.8 ml/hr, p = 0.08) than did the remaining 35 patients. This study has a 96% chance (1-beta) of detecting a 50% (30 ml) reduction in fetal urine output.

CONCLUSIONS

Daily maternal ingestion of 60 mg of aspirin did not decrease fetal urine output or amniotic fluid volume.

Low-dose aspirin therapy to prevent preeclampsia

OBJECTIVE

Our aim was to test the hypothesis that acetylsalicylate (aspirin) treatment reduces the incidence or severity of pregnancy-associated hypertension.

STUDY DESIGN

Patients were nulliparous, healthy, and with a singleton gestation at between 20 and 22 weeks' gestation. A sample size of 600 patients was calculated on the basis of p < or = 0.05 and 90% power of observation. A 2-week placebo-controlled "run-in" was used to select compliant patients. Randomization occurred at 24 weeks, with 60 mg of aspirin or placebo treatment from randomization to delivery.

RESULTS

Follow-up was maintained on 99% of the patients. The randomized patients had a 94% pill compliance index. At randomization, serum thromboxane medians were similar in both groups. Thromboxane B2 levels in the aspirin group decreased significantly from baseline at 29 to 31 weeks, 34 to 36 weeks, and at delivery as compared with an overall increase in the placebo group. Preeclampsia developed in five of 302 women (1.7%) who received aspirin versus 17 of 302 (5.6%) who received the placebo (p = 0.009). Preeclampsia was severe in one aspirin and in six placebo recipients (p = 0.06).

CONCLUSION

Daily ingestion of 60 mg of aspirin beginning at 24 weeks' gestation significantly reduced the occurrence of preeclampsia.

Maternal risk factors and their influence on fetal anthropometric measurements

OBJECTIVE

Our purpose was to determine if and when maternal risk factors and fetal sex have an impact on specific fetal anthropometric measurements assessed by ultrasonography.

STUDY DESIGN

Serial ultrasonographic examinations were performed on 1205 fetuses of indigent multiparous women who ultimately gave birth at term. Femur length, abdominal circumference, and head circumference measurements were obtained at mean gestational ages of 18, 25, 31, and 36 weeks, and an estimated fetal weight was calculated. At birth the infant was weighted and head circumference, abdominal circumference, femur length, and crown-heel length measurements were made. Regression analyses were used to determine the effect on each measurement of maternal race, height, body mass index, hypertension, weight gain, smoking, previous low birth weight, and fetal sex.

RESULTS

Acting through their effect on head circumference, abdominal circumference, and fetal length, each of the risk factors and female sex were shown to have a negative effect on fetal weight. The timing of the impact, its magnitude, and the specific anthropometric measurement affected were different for each of the risk factors.

CONCLUSIONS

The impact of maternal risk factors and fetal sex on estimated fetal weight has been demonstrated to occur first in specific gestational age windows and is mediated through effects on specific fetal anthropometric measurements.

Pregnancy outcome following a second-trimester loss

OBJECTIVE

To evaluate the association between fetal loss in the second trimester and subsequent adverse birth outcomes.

METHODS

We identified 95 women in our system who had a pregnancy loss at 13-24 weeks in the years 1985-1990 and tabulated the rates of preterm delivery, stillbirth, and neonatal death in the next pregnancy. We compared these outcomes to two groups: women who delivered at 25-36 weeks in their index pregnancy and those who delivered at term in their index pregnancy.

RESULTS

Thirty-nine percent of women who had a pregnancy loss at 13-24 weeks in the index pregnancy had a preterm delivery in their next pregnancy, 5% had a stillbirth, and 6% had a neonatal death, with all outcomes worse than those found in the two control populations. Delivery at 19-22 weeks in the index pregnancy was associated with a 62% preterm delivery rate in the subsequent pregnancy.

CONCLUSION

A second-trimester loss, especially one occurring at 19-22 weeks, is associated with a poor prognosis in the subsequent pregnancy.

Anthropometric assessment of body size differences of full-term male and female infants

OBJECTIVE

To determine gender-specific differences in anthropometric characteristics of full-term male and female infants.

METHODS

Twelve hundred five term newborn infants were examined. All measures of length and skinfold thickness were performed in a standardized manner.

RESULTS

After adjusting for confounding variables by regression analysis, we found that nearly all length and circumference measurements were significantly smaller in female infants than in male infants but that subcutaneous fat deposition in female infants was significantly increased. However, there was no difference in the ponderal index between male and female newborns, indicating that this measure does not correlate with newborn fat deposition across the sexes.

CONCLUSIONS

Despite being shorter and having smaller circumferences, female infants have more subcutaneous fat than male infants. The ponderal index is not useful as a measure of fatness when the sexes are compared. We speculate that the greater subcutaneous fat deposition in female infants may be related to their better neonatal outcomes.

A multicenter study of preterm birth weight and gestational age-specific neonatal mortality

OBJECTIVE

This analysis was performed to present updated neonatal mortality data by age and birth weight for preterm newborns and to demonstrate the influence of plurality, ethnicity, and infant sex on mortality.

STUDY DESIGN

Preterm birth weight and gestational age-specific mortality rates were compiled from the five centers that participated in the March of Dimes Multicenter Preterm Birth Prevention Project. In each center gestational age was assessed by standardized methods. A birth weight and gestational age-specific mortality chart for preterm births was created with live-birth data.

RESULTS

In each birth weight group mortality decreased as the gestational age advanced; for each gestational age group heavier infants had less mortality. Female infants < 29 weeks survived better than male infants, and singletons < 29 weeks survived better than twins. Survival for black preterm newborns was better than that of whites but differences were not significant. Mortality for black term infants was significantly higher. The largest improvement in survival occurred between 25 and 26 weeks. At 30 weeks survival was > 90% and improved < 1% per week thereafter.

CONCLUSIONS

When compared with rates in previous reports, mortality rates appear to have improved, especially at gestational ages < 29 weeks. These data may be useful in decision-making and in counseling patients at risk for preterm delivery.

Neonatal periventricular-intraventricular hemorrhage after maternal beta-sympathomimetic tocolysis. The March of Dimes Multicenter Study Group

OBJECTIVE

Our objective was to determine if the rate of periventricular-intraventricular hemorrhage is increased in the offspring of women who received a beta-sympathomimetic agent as part of the management of preterm labor.

STUDY DESIGN

This retrospective study consists of 2827 women who were delivered of a singleton, live infant free of congenital neurologic anomalies between 25 and 36 completed weeks of gestation during a multicenter preterm birth prevention trial. The data were analyzed, adjusting for type of tocolytic agent, race, infant sex, gestational age, birth weight, health care center, route of delivery, indication for delivery, intrapartum fetal distress, respiratory distress syndrome, and neonatal sepsis.

RESULTS

The overall incidence of periventricular-intraventricular hemorrhage in this population was 5.6%. In a univariate analysis in which no adjustment was made for potentially confounding variables, beta-sympathomimetic tocolysis was found to be associated with nearly a fourfold increase in the incidence of periventricular-intraventricular hemorrhage when compared with the use of either magnesium sulfate or no tocolytic agent. The results of a multivariate regression analysis revealed that beta-sympathomimetic agents were associated with a statistically significant increase in the overall incidence of periventricular-intraventricular hemorrhage (odds ratio 2.47, 95% confidence interval 1.34 to 4.56, p = 0.004) and a similar, but not significant, increase in the incidence of grades 3 and 4 periventricular-intraventricular hemorrhage (odds ratio 2.50, 95% confidence interval 0.96 to 6.48, p = 0.06).

CONCLUSION

beta-Sympathomimetic tocolytic therapy may be associated with a more than twofold increase in the incidence of neonatal periventricular-intraventricular hemorrhage.

The relationships among psychosocial profile, maternal size, and smoking in predicting fetal growth retardation

OBJECTIVE

We explored the relationships among measures of psychosocial well-being, maternal size, and smoking in predicting infant size at birth.

METHODS

Participants in this population-based cohort study were drawn from public health prenatal clinics in Jefferson County, Alabama during 1985-1988. Para 1 and 2 women were screened for 11 risk factors for low birth weight, including small stature, a previous low birth weight infant, and smoking.

RESULTS

Poor scores on five of six psychosocial scales, as well as on a combined profile, were associated with a significantly higher relative risk of fetal growth retardation (FGR) only in thinner women, defined as having a body mass index less than the median (relative risk [RR] 2.11, 95% confidence interval [CI] 1.47, 3.04). A significant association between the psychosocial profile and birth weight was demonstrated for thin women in a multivariate analysis adjusting for gestational age, race, infant sex, and smoking (P = .0003). The relationship remained significant when hypertension, alcohol and drug use, and weight gain were added to the model (P = .003). In women with a body mass index above the median, a poor psychosocial profile showed little association with FGR (RR 1.20, 95% CI 0.73, 1.98) and did not have a significant association with birth weight. A poor profile had a greater association with FGR in non-smokers (RR 2.04, 95% CI 1.29, 3.22) than in smokers (RR 1.4, 95% CI 0.95, 2.06).

CONCLUSIONS

Greater pre-pregnancy weight for height appears to protect against the adverse effects of a poor psychosocial profile in a population of poor, primarily black women. In thinner women, both smoking and a poor psychosocial profile were associated with a substantially increased rate of FGR, indicating a subgroup of women who may receive greater benefits from intervention programs.

Serum folate and fetal growth retardation: a matter of compliance?

Serum folate levels were measured at 30 weeks' gestational age in 289 pregnant women, each of whom had been provided with folate supplementation at enrollment in prenatal care. There was a significant association between low serum folate levels and fetal growth retardation. High folate levels were most likely explained by recent folic acid intake. Therefore, we were concerned that the decreased fetal growth associated with low folate levels may have been related to a combination of psychological and behavioral characteristics for which low serum folate levels were only a surrogate measure. A profile of maternal psychosocial status was created, which included measures of depression, anxiety, self-esteem, mastery, stress, and social support. Poorer psychological scores were significantly related to lower serum folate levels. However, in women with both good and poor psychosocial scores, high folate levels were significantly associated with increased birth weight, a relationship that persisted even after adjusting for maternal race, body mass index, smoking, history of a low birth weight infant, and infant gender. Our findings suggest that women with good psychosocial scores are more likely to take folate, but that the use of folate itself is related to a lower risk of fetal growth retardation and increased birth weight.

The influence of previous low birth weight on birth weight, gestational age, and anthropometric measurements in the current pregnancy

The effect of a previous low birth weight birth (less than 2750 g) was examined using a series of regression analyses. Effects on birth weight were partitioned into those associated with preterm delivery (128 g) and term delivery (178 g). Among term births, a mean difference of 107 g was associated with a previous birth of less than 2750 g, even after controlling for other risk factors including smoking, drug and alcohol use, maternal race, size, and hypertension. The pattern of measurements seen after a previous birth of less than 2750 g included significantly smaller head, chest, abdomen, arm, and thigh circumferences, but an insignificant impact on skinfold thicknesses and no significant effect on length measurements.

Etiologies of preterm birth in an indigent population: is prevention a logical expectation?

To assess the expectations of preterm birth prevention, we determined the causes of preterm birth in a population of indigent women. We studied 13,119 singleton births in a predominantly black, indigent population occurring between November 1982 and April 1986 to identify the proportion of preterm births that may have been prevented using current treatment modalities. Forty-four percent of the preterm births occurred at 35 to 36 weeks' gestational age, a time when most practitioners do not attempt tocolysis. Of the remainder, 17% occurred before 35 weeks but were indicated for maternal medical or obstetric complications, and another 17% occurred before 35 weeks but followed spontaneous premature rupture of the membranes. Therefore, of the 1445 preterm births, we calculated that only 336 (23.2%) were theoretically preventable. A fourth of these presented at less than 3 cm cervical dilatation and were treated appropriately with tocolytics, but delivered anyway. Therefore, most of the potentially preventable births occurred in the group that presented with cervical dilatation of more than 3 cm. We conclude that improving the preterm birth rate significantly below current levels may be difficult to achieve.

Is indicated or spontaneous preterm delivery more advantageous for the fetus?

We performed a case-control study to determine whether fetuses delivered prematurely because of pregnancy complications (primarily pregnancy-associated hypertensive disease) had a different neonatal course than that of those born after either spontaneous preterm labor or after premature rupture of the membranes. Two case-control populations were matched by gestational age at delivery, fetal sex, and race. There was no perinatal survival advantage in babies delivered from "stressed" pregnancies. Selected neonatal morbidities were generally similar, but there was an increased incidence of necrotizing enterocolitis in babies born after preterm labor and a higher incidence of both necrotizing enterocolitis and neonatal sepsis after premature rupture of the membranes. We conclude that a "stressed" pregnancy confers a negligible survival advantage to the fetus.

Evaluation of a risk scoring system as a predictor of preterm birth in an indigent population

A risk scoring system designed to predict spontaneous preterm birth was implemented in a large, indigent population as part of a multicenter trial of preterm birth prevention. A total of 7478 women with singleton gestations were screened and followed up prospectively at the Birmingham project center. Patients who had an indicated preterm delivery or a fetal anomaly were excluded from the study population. Analysis by assigned risk score and parity showed that, whereas the sensitivity and positive predictive value were better in multiparous women than in nulliparous women, overall the values were low. Logistic regression analyses of the multiparous and nulliparous populations showed independent sets of significant (p less than or equal to 0.05) risk variables. A history of preterm delivery and a low prepregnancy weight were the most predictive risk factors in the multiparous and nulliparous models, respectively. We conclude that the clinical usefulness of a risk scoring system to predict spontaneous preterm birth in an indigent population is limited.

The Alabama preterm birth prevention project

A preterm birth prevention program consisting of risk scoring, intensive weekly observation including cervical examinations, and detailed education about preterm labor signs and symptoms was tested in a predominantly black, indigent population. One thousand high-risk women were randomized to treatment or control groups. Although more preterm labor was diagnosed and treated in the treatment group, there were no significant differences between the groups with respect to mean birth weight or gestational age, spontaneous preterm delivery rates, or low or very low birth weight rates. The rates of respiratory distress syndrome and fetal and neonatal mortality, although greater in the treatment group, were not statistically different. However, the treatment-group infants had significantly more intracranial hemorrhages and spent more days on ventilators. At this institution, the preterm birth prevention program was not effective.

Catecholamine secretion in fetal adaptation to stress

From the beginning of labor, the fetus must successfully adapt from intrauterine life to the stress of birth and, finally, to extrauterine life. The role of hormones known as catecholamines in this adaptive mechanism is described. An understanding of the physiology of catecholamine secretion will enhance the nursing care of mothers and their infants during this important transitional period.

Warning symptoms, uterine contractions, and cervical examination findings in women at risk of preterm delivery

The presence of various reputed warning signs of preterm labor, the frequency of contractions, and the presence of cervical examination findings and their value in predicting preterm labor and spontaneous preterm delivery were assessed. The frequency of contractions and all cervical examination findings increased during pregnancy, as did backache, pressure, and cramping. The frequency of diarrhea, discharge, and bleeding remained constant. Of the various warning signs, only diarrhea and discharge were associated with the diagnosis of preterm labor. None of the warning signs were associated with spontaneous preterm delivery. Various patterns of contractions tended to be associated with higher rates of preterm labor and preterm delivery, but results were generally not statistically significant. Most cervical examination findings were statistically associated with both preterm labor and preterm delivery.

Amniotic fluid lipid profiles: a rapid gas chromatographic method

The lipid extract of amniotic fluid has been analysed for the important fatty acids derived mainly from the lecithin component of lung surfactant. Using gas-liquid chromatography and mass spectrometry, these fatty acids have been identified. A positive correlation between certain lipid profiles and lack of lung surfactant with its associated respiratory problems for the newborn infant has been demonstrated.