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Reaching the limit of neonatal viability: How do we answer the question “how small is too small”?

Sir, In the last two decades, changes in neonatal care have allowed us to reach results that were unexpected in the past. Many very premature infants can actually survive, but unfortunately disability among surviving infants of 22–26 wk ranges from 65% to 26%, respectively [1,2]. There is growing concern about the appropriateness of full intensive therapy for babies of borderline viability and, according to the Committee on Bioethics of the American Academy of Paediatrics, we should remember that we act not only as physicians but also as moral agents. [3]. In a recent issue of Acta Pædiatrica, Malcolm Levene reviewed the literature for survival studies concerning infants born at 21–27 wk from 1990 onwards and could not find any studies reporting improved survival when two successive cohorts, both born in the 1990s, were compared [4]. After reading the views of Levene, we retrospectively analysed our data for all liveborn infants between 22 and 27 wk completed gestation admitted to our neonatal intensive care unit (NICU) between 1994 and 2003. Our NICU is a referral centre with approximately 170 admissions per year, coming from nearly 3000 deliveries per year with a prevalence of high-risk pregnancies of more than 30%. There is no triage before admission to NICU. The survival rate at 27 wk has remained stable at 75–78% in the last decade, and survival without “major disability” (as defined in the paper by Levene) is 88%. Concerning babies born at 22–26 wk of gestation, we have compared 56 liveborn infants born between 1994 and 1998 (period A) with 64 liveborn infants born between 1999 and 2003 (period B). Mean gestational age was 25.1+1.1 wk in period A and 25.2+1.2 wk in period B, while mean birthweight was 708+172 g in period A and 712+201 g in period B. No differences were found concerning the incidence of caesarean section (54% vs 62%), out born infants (4% vs 6%) and intrauterine growth retardation (21% vs 17%), while prenatal steroids treatment significantly increased from 48% in period A to 79% in period B (p50.02). Overall survival at 1 y of age was 37.5% in period A and 53.1% in period B. Given the small number of infants for every single gestational age, we grouped together 22–24-wk infants and 25–26-wk infants and found that, in the former, survival decreased from 25% in period A to 12.5% in period B, while in the latter it rose from 42.5% to 66.7% ( p50.05). The incidence of major disability was 75% in 22–24-wk survivors and 48% in 25–26-wk survivors, without any significant difference between the two periods. Although our follow-up reaches 92% compliance, our data for severe disability in the most recent cohort have to be interpreted with caution because five infants are still less than 6 mo old. During the 1990s, we only obtained a significant improvement in survival for preterm babies from 25 wk onwards. Survival of 22–24-wk infants in the second cohort was probably affected by the withdrawal of care and remained occasional. We are now convinced that our efforts should be aimed at improving the intact survival of 25–26-wk infants before trying to save more 22–24-wk newborns. Our data lead us to agree with Levene that intensive care for the most immature infants should be viewed as an experimental therapy [4]. Keeping in mind that we should always act in the best interest of the patient, we can try to answer to the question “how small is too small?” [5] in 2004: 24 wk is actually too small and we do not want to surpass this limit with any overmedication.