Temporal trends in neonatal outcomes following iatrogenic preterm delivery

Abstract

BackgroundPreterm birth rates have increased substantially in the recent years mostly due to obstetric intervention. We studied the effects of increasing iatrogenic preterm birth on temporal trends in perinatal mortality and serious neonatal morbidity in the United States.MethodsWe used data on singleton and twin births in the United States, 1995-2005 (n = 36,399,333), to examine trends in stillbirths, neonatal deaths, and serious neonatal morbidity (5-minute Apgar ≤3, assisted ventilation ≥30 min and neonatal seizures). Preterm birth subtypes were identified using an algorithm that categorized live births <37 weeks into iatrogenic preterm births, births following premature rupture of membranes and spontaneous preterm births. Temporal changes were quantified using odds ratios (OR) and 95% confidence intervals (CI).ResultsAmong singletons, preterm birth increased from 7.3 to 8.8 per 100 live births from 1995 to 2005, while iatrogenic preterm birth increased from 2.2 to 3.7 per 100 live births. Stillbirth rates declined from 3.4 to 3.0 per 1,000 total births from 1995-96 to 2004-05, and neonatal mortality rates declined from 2.4 to 2.1 per 1,000 live births. Temporal declines in neonatal mortality/morbidity were most pronounced at 34-36 weeks gestation and larger among iatrogenic preterm births (OR = 0.75, CI 0.73-0.77) than among spontaneous preterm births (OR = 0.82, CI 0.80-0.84); P < 0.001. Similar patterns were observed among twins, with some notable differences.ConclusionIncreases in iatrogenic preterm birth have been accompanied by declines in perinatal mortality. The temporal decline in neonatal mortality/serious neonatal morbidity has been larger among iatrogenic preterm births as compared with spontaneous preterm births.

Trends of preterm birth and low birth weight in Japan: a one hospital-based study

“…In contrast, term-LBW did not increase, indicating that the observed increase in LBW can probably be explained by the increase in earlier deliveries (i.e., PTB). The finding that the increase in medically indicated PTB was larger than that in spontaneous PTB was consistent with previous studies in western countries [7,11,14,20]. Although the increase in PTB in western countries has been almost entirely among the late preterm (34 to 36 weeks) [5,6,21], the increase in PTB at less than 33 weeks also accounted for a small fraction of the increase in total PTB in the present study, consistent with the national vital statistics in Japan.…”

“…These contrasting trends have raised questions about the simultaneous roles of obstetric interventions as both a contributor to the rise in PTB and to the improvements in PTB-associated mortality [5,7,13,14]. However, the number of studies addressing the issue of the benefits and risks of obstetric interventions is still limited.…”

Gestational Age and Pregnancy Outcomes

“…In most studies, about 50% of all preterm births follow spontaneous preterm labor, and approximately 30% of preterm births result from premature rupture of the membranes. Obstetric intervention or iatrogenic preterm birth explains much of the increase seen in preterm births [12,13]. Also, prior spontaneous preterm delivery is strongly associated with recurrence in the current pregnancy.…”

Trends in the Distribution of Gestational Age and Contribution of Planned Births in New South Wales, Australia

“…Most previous studies have focused on outcomes following late preterm birth (32–36 weeks), however their findings have been mixed with some reporting reduced, [16], [17] and others improved perinatal survival and health. [14], [15], [18] More recent contention has been around planned births conducted at early term and before 39 weeks, however there is less evidence surrounding its effectiveness and safety. Nevertheless, studies suggest increased neonatal morbidity amongst these infants compared to those born at 39 weeks or greater [11]–[13].…”