Mortality and Morbidity of Infants Born Extremely Preterm at Tertiary Medical Centers in China From 2010 to 2019

Abstract

Importance: Extreme prematurity is associated with a substantial burden on health care systems worldwide. However, little is known about the prognosis of infants born extremely preterm in developing countries, such as China.

Objective: To describe survival and major morbidity among infants born extremely preterm in China over the past decade.

Design, setting, and participants: This retrospective cohort study was conducted from January 1, 2010, through December 31, 2019. Included individuals were infants with gestational age less than 28 weeks discharged from 1 of 68 neonatal intensive care units located in 31 provinces in China. Data were analyzed from August through October 2020.

Exposure: Extremely preterm birth.

Main outcomes and measures: Survival to discharge and major morbidity (ie, bronchopulmonary dysplasia, grades III-IV intraventricular hemorrhage, white matter injury, stage II-III necrotizing enterocolitis, sepsis, or severe retinopathy of prematurity) were measured.

Results: Among 8514 eligible infants, 5295 (62.2%) were male and 116 infants (2.0%) were small for gestational age (SGA). Overall, 5302 infants (62.3%) survived to discharge. The survival rate was 1 of 21 infants (4.8%) at 22 weeks, 13 of 71 infants (18.3%) at 23 weeks, 144 of 408 infants (35.3%) at 24 weeks, 480 of 987 infants (48.6%) at 25 weeks, 1423 of 2331 infants (61.0%) at 26 weeks, and 3241 of 4692 infants (69.1%) at 27 weeks. Survival increased from 136 of 241 infants (56.4%; 95% CI, 50.1%-62.7%) in 2010 to 1110 of 1633 infants (68.0%; 95% CI, 65.7%-70.2%) in 2019 for infants born at 24 to 27 weeks (mean difference, 11.5%; 95% CI, 4.9%-18.2%; P < .001), without a significant change for infants born at less than 24 weeks. Major morbidity was found in 5999 of 8281 infants overall, for a rate of 72.4%, which increased from 116 of 223 infants (52.0%; 95% CI, 45.4%-58.6%) to 1363 of 1656 infants (82.3%; 95% CI, 80.5%-84.1%) from 2010 to 2019 (mean difference, 30.3%; 95% CI, 23.5%-37.1%, P < .001). Regional variations in survival were identified, with an almost 2-fold increase (1.94-fold; 95% CI, 1.66-2.27; P < .001) from 188 of 474 infants (39.7%) in northwest China to 887 of 1153 infants (76.9%) in north China. Gestational age (adjusted risk ratio [aRR], 1.084; 95% CI, 1.063-1.105; P < .001), birth weight (aRR, 1.028; 95% CI, 1.020-1.036; P < .001), premature rupture of membranes (aRR, 1.025; 95% CI, 1.002-1.048; P = .03), and antenatal steroids (aRR, 1.029; 95% CI, 1.004-1.055; P = .02) were associated with improved survival, while being born SGA (aRR, 0.801; 95% CI, 0.679-0.945; P = .01), being male (aRR, 0.975; 95% CI, 0.954-0.997; P = .02), multiple birth (aRR, 0.955; 95% CI, 0.929-0.982; P = .001), having a mother with gestational diabetes (aRR, 0.946; 95% CI, 0.913-0.981; P = .002), and low Apgar score (aRR, 0.951; 95% CI, 0.925-0.977; P < .001) were found to be risk factors associated with decreased chances of survival.

Conclusions and relevance: This study found that infants born extremely preterm were at increased risk of mortality and morbidity in China, with a survival rate that improved over time and a major morbidity rate that increased. These findings suggest that more active and effective treatment strategies are needed, especially for infants born at gestational age 25 to 27 weeks.

Figure 1.. Survival to Discharge by Gestational Age (GA)

Polyline indicates survival rate of infants born extremely preterm; whiskers, 95% CI; columns, analysis stratified by GA. The survival rate, adjusted for GA, birth weight, and study site improved over time: adjusted risk ratio for the change per year, 1.053; 95% CI, 1.046-1.060; P < .001. The total number of infants in each GA category is listed in Table 1.

Figure 2.. Major Morbidity Prevalence

BPD indicates bronchopulmonary dysplasia; IVH, intraventricular hemorrhage; NEC, necrotizing enterocolitis; ROP, retinopathy of prematurity; WMI, white matter injury; columns, prevalence of major neonatal complications; major morbidity, presence of BPD, IVH grade III to IV, WMI, NEC stage II to III, sepsis, or severe ROP; polyline, trend in major morbidity; whiskers, 95% CI. Risk ratio adjusted for gestational age, birth weight, and study site for the change per year, 1.055; 95% CI, 1.048-1.061; P < .001.