Changes in the gestational age distribution among U.S. singleton births: impact on rates of late preterm birth, 1992 to 2002.

There is mounting evidence that infants born late preterm (34-36 weeks) are at greater risk for morbidity than term infants. This article examines the changing epidemiology of gestational length among singleton births in the United States, from 1992 to 2002. Analyzing gestational age by mode of delivery, the distribution of spontaneous births shifted to the left, with 39 weeks becoming the most common length of gestation in 2002, compared with 40 weeks in 1992 (P < 0.

Research agenda for preterm birth: recommendations from the March of Dimes.

Preterm birth (PTB) is a common, serious, and costly health problem affecting nearly 1 in 8 births in the United States. Burdens from PTB are especially severe for the very preterm infant (<32 weeks' gestation), comprising 2% of all US births. Successful prevention needs to include newly focused and adequately funded research, incorporating new technologies and recognition that genetic, environmental, social, and behavioral factors interact in complex pathogeneses and multiple pathways leading to PTB.

Estimated effect of 17 alpha-hydroxyprogesterone caproate on preterm birth in the United States.

Objective: A multicenter, randomized placebo-controlled trial among women with singleton pregnancies and a history of spontaneous preterm birth found that weekly injections of 17 alpha-hydroxyprogesterone caproate (17P), initiated between 16 and 20 weeks of gestation, reduced preterm birth by 33%. The current study estimated both preterm birth recurrence and the potential reduction in the national preterm birth rate.

Methods: Using 2002 national birth certificate data, augmented by vital statistics from 2 states, we estimated the number of singleton births delivered to women eligible for 17P through both a history of spontaneous preterm birth and prenatal care onset within the first 4 months of pregnancy.

Mode of conception, placental morphology and perinatal outcome of twin gestations.

Objective: To compare the perinatal outcome and placental morphology of twins conceived by assisted reproductive technologies (ART) or natural conception (NC).

Methods: The present retrospective study included 88 twin pairs. Methods of ART included in vitro fertilization, intrauterine insemination, embryo transfer and induced ovulation.

The changing epidemiology of multiple births in the United States.

Objective: To describe changes in the epidemiology of multiple births in the United States from 1980 to 1999 by race, maternal age, and region; and to examine the impact of these changes on birth weight-specific infant mortality rates for singleton and multiple births.

Methods: Retrospective univariate and multivariable analyses were conducted using vital statistics data from the National Center for Health Statistics.

Results: Between 1980 and 1999, the overall multiple birth ratio increased 59% (from 19.