The Swedish national prospective study on extremely low birthweight (ELBW) infants. Incidence, mortality, morbidity and survival in relation to level of care

Abstract

In a 2-year (1990-92) prospective national investigation, comprising all stillborn and live-born ELBW infants with a birthweight of < or = 1000 g born at 23 completed weeks of gestation or more, we examined the incidence, neonatal mortality, major morbidity and infant survival in relation to level of care and place of residence. A total of 633 ELBW infants were live-born, i.e. 0.26% of all live-born infants, and 298 were stillborn. The average neonatal mortality was 37% and 91% at 23 weeks, 70% at 24 weeks, and 40% at 25 weeks of gestation. Of neonatal survivors, 8% had intraventricular haemorrhage grade 3, 10% retinopathy of prematurity of stage > or = 3, 2% necrotizing enterocolitis, and 28% were oxygen-dependent at a time corresponding to 36 weeks of gestation. In all, 77% were treated with mechanical ventilation, whereas 19% survived without, almost all of them being CPAP treated. Infant mortality among infants born at level III (tertiary centres) was 30%, at level IIa (with full perinatal service) 46% and at level IIb (with basic neonatal service) 55%. Only 1% was born at hospital level I. Regarding the relation to place of residence, the mortality rates among infants residing in the areas served by levels III, IIa and IIb hospitals were 36%, 45% and 41%, respectively. The referral system thus functioned well, but can be improved, and increased perinatal referral, at borderline perinatal viability, might provide a better quality of care and a better chance of survival.

A National Short-Term Follow-Up Study of Extremely Low Birth Weight Infants Born in Finland in 1996–1997

“…The high stillbirth rate in our study (34%) was similar to that of the Swedish national report 21 (32%) but higher than in the studies by Emsley et al 9 (22%) and Battin et al 23 (14%). The majority of postnatal deaths occur during the first 3 days.…”

“…The deteriorated outcome was primarily caused by visual impairments, whereas the incidence of cerebral palsy remained constant. In studies from the 1990s, neonatal survival rates of infants born at 22 to 23 GWs varied from 0% to 25% 21,23,28 and was 9% in our study, which was significantly lower than that of the infants born at 24 to 25 GWs (60%). However, statistically significant differences in neonatal survival among GW groups at 25 to 29 GWs were not found.…”

“…Besides of low survival rate, the infants born at 22 to 23 GWs also have poor outcome: long-term disability rates varied in previously mentioned studies from 67% to 100%. 21,23,28 In our study, no infant born at 22 to 23 GWs had completely normal short-term follow-up results.…”

“…from 22 to 28 GWs. 21,22 At the border of viability, there is also a risk for nonoptimal prenatal treatment resulting in stillbirth. Furthermore, there is a gray zone between stillborn and live-born ELBW infants: infants with a 1-minute Apgar score of zero may be resuscitated, as was the case in 3 infants of our study population.…”

“…32 Based on survival and outcome results, some countries, such as Sweden, Norway, and Canada have given recommendations about the treatment of the extremely immature infants born at 22 to 25 GWs. 21,33,34 The national advice usually justifies active antenatal and perinatal treatment of infants born at 25 GWs. The treatment of infants born at 23 to 24 GWs is recommended to be individualized, and it is usually suggested not to vigorously treat infants born at 22 GWs, although the possible inaccuracies in gestational age estimation should be kept in mind.…”