Preterm birth (PTB) is the leading cause of infant mortality worldwide. Changes in PTB rates, ranging from −90% to +30%, were reported in many countries following early COVID-19 pandemic response measures (‘lockdowns’). It is unclear whether this variation reflects real differences in lockdown impacts, or perhaps differences in stillbirth rates and/or study designs. Here we present interrupted time series and meta-analyses using harmonized data from 52 million births in 26 countries, 18 of which had representative population-based data, with overall PTB rates ranging from 6% to 12% and stillbirth ranging from 2.5 to 10.5 per 1,000 births. We show small reductions in PTB in the first (odds ratio 0.96, 95% confidence interval 0.95–0.98, P value <0.0001), second (0.96, 0.92–0.99, 0.03) and third (0.97, 0.94–1.00, 0.09) months of lockdown, but not in the fourth month of lockdown (0.99, 0.96–1.01, 0.34), although there were some between-country differences after the first month. For high-income countries in this study, we did not observe an association between lockdown and stillbirths in the second (1.00, 0.88–1.14, 0.98), third (0.99, 0.88–1.12, 0.89) and fourth (1.01, 0.87–1.18, 0.86) months of lockdown, although we have imprecise estimates due to stillbirths being a relatively rare event. We did, however, find evidence of increased risk of stillbirth in the first month of lockdown in high-income countries (1.14, 1.02–1.29, 0.02) and, in Brazil, we found evidence for an association between lockdown and stillbirth in the second (1.09, 1.03–1.15, 0.002), third (1.10, 1.03–1.17, 0.003) and fourth (1.12, 1.05–1.19, <0.001) months of lockdown. With an estimated 14.8 million PTB annually worldwide, the modest reductions observed during early pandemic lockdowns translate into large numbers of PTB averted globally and warrant further research into causal pathways.

Background: Experts recommend assessing preterm infant growth against fetal growth patterns. However, obtaining accurate estimates of healthy fetal growth from preterm infants is challenging as many had intrauterine faltering growth.Objectives: To improve preterm infant growth assessments by developing Fenton third‐generation sex‐specific preterm growth charts based on anthropometric distributions of preterm infants without abnormal fetal growth. We also aimed to evaluate the consistency of the new charts' growth velocities.Data Sources: From the last search for the 2013 Fenton growth charts to November 2024, MEDLINE and EMBASE databases, grey literature, as well as US Vital statistics and iNeo Consortium.Study Selection and Data Extraction: We followed systematic review methodology to identify population‐based sex‐specific anthropometric estimates of preterm cohorts without abnormal fetal growth beginning ≤ 24 weeks of gestation. Specified a priori, outcomes included newborn sex‐specific estimates of birthweight, length, and head circumference.Synthesis: We followed PRISMA guidelines. Literature screening and quality assessment were performed in duplicate. We harmonised weight, length, and head circumference weighted‐average meta‐analyses with the World Health Organization growth standard and rescaled the charts' x‐axis from completed gestational weeks to exact gestational age (weeks and days).Results: Seven studies from 15 countries (Australia, Brazil, Canada, China, Finland, Israel, Italy, Japan, Netherlands, New Zealand, Sweden, Switzerland, Spain, United Kingdom and United States) were included, representing 4.8 million births 22–42 weeks of gestation. 174,184 were < 30 weeks gestational age. The Fenton third‐generation preterm growth charts' weights showed improved growth velocity across percentiles with consistent declines for weight, length and head circumference velocity as post‐menstrual age increased. The birthweight meta‐analysis curves had similar shapes to fetal ultrasound estimates.Conclusions: The Fenton third‐generation preterm infant growth chart curves demonstrate improved and more uniform slopes across percentiles and closer alignment with fetal ultrasound estimates, offering a growth standard for preterm infants.Prospero Registration: CRD42024589756

To reduce the incidence of necrotizing enterocolitis (NEC) among very preterm infants in the Calgary Health Region to ≤2% within 2 years. A multidisciplinary team developed key drivers for NEC. Targeted interventions included strategies to increase mothers’ own milk (MOM), improve compliance with feeding regimens, standardize management of feeding intolerance, prevent intestinal microbial aberrations, and feed conservatively during blood transfusion and the treatment of patent ductus arteriosus. The outcome measure was NEC (≥ stage 2). Changes in NEC rates were examined among racial and ethnic groups. Process measures included MOM feeding at discharge, the difference between actual and expected time to reach full feeds, lowest hemoglobin, and the duration of empirical antibiotics. Growth, the rate of blood transfusion, and the duration of parenteral nutrition were balancing measures. The preintervention, intervention, and sustainment periods were January 2013 to June 2016, July 2016 to December 2018, and December 2018 to December 2021, respectively. We included 2787 infants born at ≤32^6/7 weeks’ gestation (1105 preintervention, 763 during intervention, and 919 in sustainment). NEC decreased from 5.6% to 1.9%. Process measures indicated increased MOM feeding at discharge, improved compliance with feeding regimens, increased lowest hemoglobin levels, and shorter durations of empirical antibiotics. Balancing measures revealed improved weight Z-scores, shorter durations on parenteral nutrition, and increased rates of blood transfusion. Quality improvement initiatives to increase MOM, improve compliance with feeding regimens, feed conservatively during blood transfusion and treatment of patent ductus arteriosus, and prevent intestinal microbial aberrations were associated with reduced NEC.