Outborn status with a medical neonatal transport service and survival without disability at two years: A population-based cohort survey of newborns of less than 33 weeks of gestation

https://doi.org/10.1016/S0301-2115(97)00243-1Get rights and content

Abstract

Objective: Prenatal events are thought to play an important role in long-term handicap, but the specific role of perinatal factors remains controversial. Our study, conducted in the context of this debate, aimed to break down the various components of perinatal management and to assess the relationship between these components and survival without disability at the age of two years. Study design: A prospective geographically-defined study was conducted in 1985 in the Paris metropolitan area. It covered 53430 births (stillbirths and live births), including 539 that occurred between 25 and 32 weeks gestation. The relationship between perinatal management and survival without disability was studied by a multivariate analysis (logistic regression). The analysis was restricted to a group of 202 infants born at 31 or 32 week's gestation, to avoid indication bias. Results: An inborn status (delivery in a tertiary care facility) exerted a protective effect on survival without disability at the age of two years (Adjusted Odds Ratio (OR)=7.51 [1.51; 37.4]), even though the area we studied possessed an excellent Medical Neonatal Transport Service. Multiple pregnancies also seemed to have a protective effect (Adjusted OR=2.45 [0.96; 6.27]). No statistically significant association was seen between survival without disability at two years and the presence of a hospital staff paediatrician in the delivery room. Conclusion: These results lead us to consider what the concept of inborn/outborn represents in the perinatal management of infants at high risk.

Introduction

Very premature infants are at high risk of mortality and disability. Prenatal events are thought to play an important role in long-term handicap [1], but the specific role of perinatal factors remains controversial. Inborn status was found to have a protective effect on neonatal survival in Ozminkowski's meta-analysis [2]. The lack of regionalization of neonatal care in the Ile de France led to the development of a Medical Neonatal Transport Service, the SMUR (Service Mobile d'Urgence et de Réanimation) at the end of the 1970s. In 1985 a French population-based survey of very premature infants, of 32 weeks gestation or less, was conducted in the Paris metropolitan area [3]. Its purpose was to describe mortality rate and outcome at two years by gestational age (GA). The present study used some of these data to examine whether a very premature infant's inborn status continued to exert a protective effect, despite the improvement in treatment of transferred or outborn infants offered by SMUR. In particular, we evaluated the role this service could play in perinatal management in view of the frequency of outborn status in very premature infants. To do this, we decomposed the various elements of perinatal management and assessed their relationship to survival without disability at the age of two years. Multivariate analysis was restricted to the subgroup of 31–32 weeks gestation to avoid indication bias.

Section snippets

Sample

The data came from the 1985 survey conducted in the Paris region [3]. That study included every public hospital with a maternity unit, every private hospital or clinic with a maternity unit handling at least 1200 births per year, and half of the private hospitals and clinics with fewer than 1200 births per year (randomly sampled). Data were collected for six months in the two first groups of hospitals and for a period of 12 months in the last group, thus achieving a sampling fraction of 1/2.

Study population

Of the 539 births, 57 live births occurred at 27–28 weeks, 100 at 29–30 weeks, and 220 at 31–32 weeks. The results for mortality and disability as related to inborn/outborn status are shown in Table 1. The infant mortality rates for live births at 27–28, 29–30, and 31–32 weeks were, respectively, 52.6%, 28.5% and 14.8%, leading to an overall mortality rate of 24.5% (88/359).

There were 220 live births at 31 or 32 weeks, none with congenital anomalies. Sixteen (7.2%) of these children had been

References (23)

  • F.P. Hadlock et al.

    Estimation of foetal weight with the use head, body and femur measurements - A prospective study

    Am J Obstet Gynecol,

    (1985)
  • P. Pharoah et al.

    Birthweight specific trends in cerebral palsy

    Arch Dis Child

    (1990)
  • R.J. Ozminkowski et al.

    Inborn/outborn status and neonatal survival: a meta-analysis of non randomised studies

    Stat Med

    (1988)
  • M. Dehan et al.

    Devenir des prématurés de moins de 33 semaines d'âge gestationnel: résultats d'une enquête menée en 1985 dans la région Parisienne

    J. Gynecol Obstet Biol Reprod

    (1990)
  • R.M. Mickey et al.

    The impact of confounder selection criteria on effect estimation

    Am J Epidemiol.

    (1989)
  • J. Bouyer

    Logistic regression in epidemiology Part I

    Epidemiol Pub Health.

    (1991)
  • J. Bouyer

    Logistic regression in epidemiology Part II

    Epidemiol Pub Health.

    (1991)
  • SAS User's guide. Raleigh, NC: SAS Institute Inc,...
  • Dixon WJ, editor. BMDP statistical software manual. Berkeley: University of California Press,...
  • L.O. Lubchenco et al.

    Intra uterine growth in lenght and head circumference as estimated from live births at gestational ages from 26 -42 weeks

    Pediatrics

    (1966)
  • A. Bastide et al.

    Evaluation of foetal weight

    SOGC J,

    (1991)
  • Cited by (70)

    • Frequency, causes and avoidability of outborn births in a French regional perinatal network

      2014, European Journal of Obstetrics and Gynecology and Reproductive Biology
      Citation Excerpt :

      The risk of imminent delivery was responsible for almost three-quarters of the contraindications to an IUT. Regionalisation is of capital importance in the management of VLBW and VPT infants, and numerous studies have already demonstrated the excess risk for outborn infants [8–13]. In the meta-analysis by Lasswell [1], the risk of death was higher in the population of infants born outside a level II maternity both for VLBW (adjusted odds ratio: 1.62, 95% CI (144–183)) and VPT infants (adjusted odds ratio: 1.55 95% CI (121–198)).

    • Obstetric air medical retrievals in the australian outback

      2013, Air Medical Journal
      Citation Excerpt :

      However, studies do show that delivery during flight is rare.4–6 Every effort should be made to transport women in preterm labor to a tertiary center before delivery because this confers significant benefits to the newborn.7–12 High-risk births will inevitably occasionally occur outside the tertiary center, especially in geographically large areas.

    • Distribution of maternity units and spatial access to specialised care for women delivering before 32 weeks of gestation in Europe

      2010, Health and Place
      Citation Excerpt :

      The delivery of these infants (1–1.5% of all births) in level III units is associated with lower mortality and higher survival without disability (Chien et al., 2001; Field et al., 1991; Moster et al., 1999; Ozminkowski et al., 1988; Phibbs et al., 1996). These effects are attributed to the technical expertise and coordination between obstetric and neonatal teams in level III and the avoidance of potentially harmful neonatal transport after birth (Harding and Morton, 1994; Merlo et al., 2005; Truffert et al., 1998). Many factors influence the success of regionalization programmes, including the willingness of obstetricians to transfer their patients, the existence of transfer protocols and cot availability in neonatal intensive care units (Attar et al., 2006; HCN, 2000).

    View all citing articles on Scopus
    View full text