Consequences of nonindicated preterm delivery in singleton gestations.

OBJECTIVE: To determine the neonatal and economic consequences of nonindicated preterm delivery in singleton gestations. STUDY DESIGN: From a database of women with high-risk pregnancies enrolled for outpatient nursing services between October 1995 and February 2000, singleton gestations with induced labor or scheduled cesarean delivery and a gestational age at delivery of 34-36 weeks were identified. Excluded were women with preterm premature rupture of the membranes or medically indicated delivery. We compared infant neonatal intensive care unit (NICU) admission rates and ventilator use for consecutive weeks and applied a cost model to determine potential savings of delaying delivery. RESULTS: A total of 1,538 pregnancies were analyzed. Risk of NICU admission declined significantly with each advancing week (by > 50%, P <.05). NICU length of stay and total nursery costs decreased significantly between weeks 35 and 36 and weeks 34 and 35. Need for ventilatory assistance increased significantly for infants admitted to the NICU between weeks 34 and 35. The incidence of respiratory distress syndrome decreased 49% between 35 and 36 weeks. CONCLUSION: Prolonging gestation 1 week beyond weeks 34 and 35 has a significant impact on improving neonatal outcome and decreasing associated costs. These factors should be considered when electing to deliver at 34 and 35 weeks.

Effect of maternal height on gestational age and birth weight in nulliparous mothers of triplets with a normal pregravid body mass index.

OBJECTIVE: To study the effect of maternal height on gestational age and birth weight of triplets born to nulliparous women with a normal pregravid body mass index (BMI). STUDY DESIGN: A 1988-2000 prospective cohort of 1,219 U.S. live-born triplets was evaluated. Patients were grouped into stature categories of 5-cm intervals. Mean values for BMI, height, maternal age, gestational age at birth, total triplet birth weight and frequencies of births at < 28 weeks and with very low birth weight were calculated for each height category. RESULTS: Maternal heights were normally distributed (mean, 165.2 +/- 6.2 cm). We found a significant positive correlation (R2 = .95), different from a zero slope (P < .01), between mean total triplet birth weight and height category. Nulliparous women who were taller than 165 cm had age, BMI and gestational age characteristics similar to those of their shorter counterparts but delivered significantly heavier triplets and were at significantly lower risk of delivering very-low-birth-weight triplets. CONCLUSION: Taller women are more likely to deliver heavier triplets and are at lower risk of delivering very-low-birth-weight triplets. This information should be included in counseling women with the potential of conceiving triplets.

A novel approach to intertriplet birth weight discordance.

OBJECTIVE: This study was undertaken to evaluate intertriplet birth weight discordance. STUDY DESIGN: Birth weight discordance greater than 25% was evaluated in a cohort of 2804 US live-born triplets. Symmetric and high- and low-skew sets were defined by the rank of the middle triplet between the heavier and the lighter triplets. Frequencies of discordance level and type were analyzed by gestational age, parity, and total triplet birth weight. RESULTS: Discordance of 25.1% to 35% and greater than 35% was found in 19.4% and 9.5% of the triplets analyzed, respectively. Frequencies of greater than 25% discordant sets demonstrated polynomial relationship to gestational age (R (2) = 0.94, P <.001) total triplet birth weight deciles (R (2) = 0.97, P <.001). Frequencies of discordance type are unchanged throughout gestation. CONCLUSION: Birth weight discordance in triplets is frequent and large and implies exhaustion of fetal growth potential despite a uterine environment that appears to perform at maximal effort in these pregnancies.

The odds of delivering one, two or three extremely low birth weight (< 1000 g) triplet infants: a study of 3288 sets.

The odds of an individual triplet pregnancy to end with neonates weighing < 1000 g (extremely low birth weight [ELBW]) are unknown. We analyzed a nationwide perinatal database collected by Matria Healthcare, Inc. (Marietta, GA) to select from 3288 triplets those weighing 500-1000 g, delivered during the period 1988-2000 in the United States. We counted the number of sets with one, two, and three ELBW neonates and compared the incidence of ELBW infants between the subsets of nulliparas and multiparas. The odds of delivering at least one ELBW infant was significantly higher among nulliparas (1:8) than among multiparas (1:14), Odds Ratio (OR) 1.9, 95% Confidence Interval (CI) 1.9, 2.5. The odds of having at least two ELBW sibs in nulliparas (1:16) is twice higher than in multiparas (1:31), OR 2.0, 95% CI 1.3, 2.9. Nulliparas and multiparas had similar odds of delivering three ELBW infants (1:29 versus 1:40, OR 1.3, 95% CI 0.9, 2.1). Nulliparas are at significantly increased risk of delivering one or two ELBW triplets. This observation is no less than alarming and highlighted by the exceptionally high risk of major neurological deficits reported among ELBW infants.

Total and individual triplet birth weights as a function of gestational age.

OBJECTIVE: Our purpose was to determine the relationship between gestational age and both the total and individual triplet birth weights. STUDY DESIGN: A 1988-2000 prospective cohort of 3238 live-born triplets in the United States was evaluated. The mean individual (heaviest, middle, and lightest) and total triplet birth weights were correlated with gestational age in nulliparous and multiparous patients. RESULTS: The mean total triplet birth weights significantly correlated with gestational age for both nulliparous women and multiparous women, but the respective regression lines were significantly different (P =.0018). The respective regression lines for individual triplets showed a significant linear correlation (R(2) = 0.996-0.998). Interparity and intraparity differences of the individual triplets' regression lines were also significantly different. CONCLUSIONS: The relationships support a model of two distinct growth periods for triplets: an age- and growth-promoting period until 33 weeks and an age-promoting growth-restricting period thereafter.

Demographic and obstetric factors influencing pregnancy outcome in twin gestations.

OBJECTIVE: Our purpose was to identify the influence of parity and previous preterm delivery on pregnancy outcome in twin gestations. STUDY DESIGN: A retrospective comparative analysis of women with twin gestations completing an outpatient preterm labor surveillance program between April 1995 and February 2000 was performed. Included were those enrolled at <24 weeks' gestation. Parity, maternal age, prepregnancy body mass index (BMI), cerclage, tocolytic use, and pregnancy outcome were identified. Data were divided into nulliparas, multiparas without previous preterm delivery, and those with previous preterm delivery. Analysis of variance and the Pearson chi2 test were used for statistical analysis. RESULTS: Data were analyzed for 1268 twin pregnancies. The mean gestational age at delivery for the multiparous women without a history of previous preterm delivery (35.3 +/- 2.7 weeks) was significantly greater than the mean gestational age at delivery for nulliparous (34.4 +/- 3.2 weeks) and multiparous women with a previous preterm delivery (34.0 +/- 3.1 weeks), P <.001. The greater gestational age at delivery in the multiparous women without a previous preterm delivery was associated with a significantly shorter newborn hospital stay and a lower need for mechanical ventilation use compared with the other groups (all P values < or =.001). CONCLUSION: In twin gestations, multiparous women without history of previous preterm delivery have a significantly greater gestational age at delivery, a lower incidence of cerclage, and a reduced neonatal hospital stay than do nulliparous women or those with a history of a previous preterm delivery.