From the Journals

Swedish strategies improve survival for premature infants

Publish date: March 26, 2019
By
Heidi Splete

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Data open doors for more questions

The wide variation in outcomes for preterm birth worldwide raise questions as to whether the success seen in Sweden is possible in other countries, Matthew A. Rysavy, MD, PhD, and Danielle E. Y. Ehret, MD, MPH, wrote in an accompanying editorial. Considerations include population demographics, current guidelines, gestational age at which intensive care is offered, and the nature of follow-up care.

Sweden already has low rates of perinatal mortality, and current guidelines call for use of antenatal corticosteroids for births at 22 weeks’ gestation. By contrast, in the United States, antenatal corticosteroids are not recommended until 23-24 weeks’ gestation, they noted.

The editorialists called particular attention to the improvements in survival at 1 year and survival without major morbidity at 22-23 weeks’ gestation. “At 22 weeks’ gestation, the stillbirth rate decreased from 65% of all births during 2004-2007 to 35% during 2014-2016, with a reciprocal increase in live births.”

Although the results are promising, and show the possibilities for improving survival, the editorialists wrote that ongoing follow up of children born prematurely is essential to inform future research, as “much remains unknown about the later-life effects of being born so early and of the therapies used to sustain life after birth.”

Dr. Rysavy is affiliated with the department of pediatrics at the University of Iowa, Iowa City; Dr. Ehret is affiliated with the department of pediatrics at the University of Vermont, Burlington. This is a summary of their editorial accompanying the article by Norman et al. (JAMA. 2019 Mar 26;321:1163-64). They reported no financial conflicts.


 

FROM JAMA

Survival rates for preterm infants improved significantly in Sweden after the adoption of new perinatal management guidelines, based on data from a study of two cohorts including 2,205 births at 22-26 weeks’ gestational age.

premature infant in incubator Herjua/Thinkstock

The impact of the recommendations has not been well studied, wrote Mikael Norman, MD, PhD, of the Karolinska Institutet, Stockholm, and his colleagues in JAMA. To determine the impact, the researchers compared data from 1,009 births at 22-26 weeks’ gestational age during 2004-2007 with 1,196 births at 22-26 weeks’ gestational age during 2014-2016, after the implementation of guidelines on “centralization of care, antenatal corticosteroid treatment, mode of delivery, a neonatologist attending at the birth, and resuscitation of infants delivered at 22, 23, and 24 weeks’ gestational age.”

The 1-year survival increased from 70% during 2004-2007 to 77% during 2014-2016; a significant improvement (P = .003).

In addition, 1-year survival with no major morbidity improved significantly between the two time periods, from 32% to 38%, respectively (P = .008).

The mothers and infants were part of EXPRESS (Extremely Preterm Infants in Sweden Study), a national, population-based, prospective cohort study. In most cases, gestational age was determined by routine antenatal ultrasound early in the second trimester, or by date of embryo transfer in cases of in vitro fertilization. The primary outcome was survival at the age of 1 year; the secondary outcome was survival at 1 year with no major neonatal comorbidity.

Among premature infants who survived at 1 year, some conditions were significantly more prevalent in the earlier birth cohort, compared with the later cohort, notably cystic periventricular leukomalacia (6% vs. 2%), any bronchopulmonary dysplasia (73% vs. 62%), and severe bronchopulmonary dysplasia (25% vs. 14%).

Although the proportion of premature births with a neonatologist attending was similar between the two cohorts, significantly more premature infants were born outside of university hospitals and transported to a level III neonatal ICU after birth during 2004-2007, compared with 2014-2016, the researchers noted.

The study findings were limited by several factors including the retrospective design of the second cohort, inability to account for fetal losses prior to 22 weeks’ gestational age, lack of data on the causes of fetal and infant deaths, potentially unknown confounding variables that impacted infant survival, and the small sample size of some gestational age groups, the researchers noted. However, the results show improvements in 1-year survival in the wake of specific guidelines on perinatal management.

Dr. Norman reported receiving grants from the Swedish Heart Lung Foundation and the H2020/European Union, as well as personal fees from a Swedish medical journal, the Swedish patient insurance, Liber, Studentlitteratur, and AbbVie. The study was funded by the Swedish Order of Freemasons’ Foundation for Children’s Welfare.

SOURCE: Norman M et al. JAMA. 2019;321:1188-99.

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