71 - One-year mortality in moderately and late preterm infants, in comparison with very preterm and term born infants: a population-based study in Finland

Monday, May 1, 2023

9:30 AM – 11:30 AM ET

Poster Number: 71
Publication Number: 71.429

Kati Renko, University of Tampere, Finland, Oulu, Pohjois-Pohjanmaa, Finland; Outi KT. Tammela, Tampere University Hospital, Tampere, Pirkanmaa, Finland; Tiina H. Luukkaala, Tampere university, Tampere, Pirkanmaa, Finland; Riitta Ojala, Tampere University Hospital, Tampere, Pirkanmaa, Finland

Presenting Author(s)

Kati Renko, MD (she/her/hers)

Neonatology fellow, PhD trainee
Oulu University Hospital and University of Tampere, Finland
Oulu, Pohjois-Pohjanmaa, Finland

Background: Preterm birth (birth at < 37weeks gestation) is a leading cause of mortality among less than five years old children. Previous studies it have been discovered that even infants born only a few weeks early have a substantially increased risk of death and morbidity when compared with full-term infants.

Objective:

The aim of the study was to investigate perinatal, neonatal and infant mortality in moderately preterm (MP) (32⁺⁰-33⁺⁶ weeks) and late preterm (LP) (34⁺⁰-36⁺⁶ weeks) infants, in comparison with very preterm (VP) (< 32weeks), early term (ET) (37⁺⁰-38⁺⁶ weeks), term (39⁺⁰-40⁺⁶ weeks), late term (LT) (41⁺⁰-41⁺⁶ weeks) and post term (PT) (≥42⁺⁰ weeks) infants.We hypothesized that the mortality decreases with increasing gestational age. We also investigated the predictors of mortality and causes of death.

Design/Methods: This national register study included all live births and stillbirths with a gestational age of at least 22⁺⁰weeks and/or a birth weight of at least 500g born in Finland from 1991 to 2016 (n=1 546 787).

Results: Perinatal, neonatal and infant mortality rates decreased with increasing gestational age and were higher in the MP and the LP infants than in infants born at term (Figure 1). Overall mortality decreased to more than half during the study period 1991-2016: perinatal mortality from 6,5%-2,6%, neonatal mortality 6,2%-1,7% and infant mortality 7%-1,8%, respectively. The association was statistically significant in all mortality categories from the year 2002 onwards (Table 1). In our study factors that were statistically significantly associated with increased mortality in all mortality categories were small for gestational age (SGA), ventilator treatment and factors associated with asphyxia, including Apgar score 0-6 and, resuscitation at birth. Instead, primiparity was a statistically significant predictor of decreased mortality risk in the respective categories. In the logistic regression model VP, MP and LP birth were statistically significant predictors associated with mortality (Table 1). The most common causes of death in MP and LP groups in perinatal, neonatal and infant period were congenital anomalies (Table 2), among which the most were chromosomal (in perinatal mortality: MP 36,5%, LP 32,9%, and in neonatal mortality LP 37,3%) and cardiovascular (in neonatal mortality: MP 54,5% and infant mortality MP 51,9% and LP 38,9%) malformations.

Conclusion(s):

Perinatal, neonatal and infant mortality decreased with increasing gestational age and by time. VP, MP and LP birth were statistically significantly associated with the risk of mortality in all three mortality categories.