Growth, lung function, and physical activity in schoolchildren who were very-low-birth-weight preterm infants

Increasing airway obstruction through life following bronchopulmonary dysplasia: a meta-analysis

Background

Few studies exist investigating lung function trajectories of those born preterm; however growing evidence suggests some individuals experience increasing airway obstruction throughout life. Here we use the studies identified in a recent systematic review to provide the first meta-analysis investigating the impact of preterm birth on airway obstruction measured by the forced expiratory volume in 1 s (FEV1) to forced vital capacity (FVC) ratio.

Methods

Cohorts were included for analysis if they reported FEV1/FVC in survivors of preterm birth (<37 weeks' gestation) and control populations born at term. Meta-analysis was performed using a random effect model, expressed as standardised mean difference (SMD). Meta-regression was conducted using age and birth year as moderators.

Results

55 cohorts were eligible, 35 of which defined groups with bronchopulmonary dysplasia (BPD). Compared to control populations born at term, lower values of FEV1/FVC were seen in all individuals born preterm (SMD -0.56), with greater differences seen in those with BPD (SMD -0.87) than those without BPD (SMD -0.45). Meta-regression identified age as a significant predictor of FEV1/FVC in those with BPD with the FEV1/FVC ratio moving -0.04 sds away from the term control population for every year of increased age.

Conclusions

Survivors of preterm birth have significantly increased airway obstruction compared to those born at term with larger differences in those with BPD. Increased age is associated with a decline in FEV1/FVC values suggesting increased airway obstruction over the life course.

Geographical Differences and Temporal Improvements in Forced Expiratory Volume in 1 Second of Preterm-Born Children: A Systematic Review and Meta-analysis

Importance

Although preterm birth is associated with later deficits in lung function, there is a paucity of information on geographical differences and whether improvements occur over time, especially after surfactant was introduced.

Objective

To determine deficits in percentage predicted forced expiratory volume in 1 second (%FEV1) in preterm-born study participants, including those with bronchopulmonary dysplasia (BPD) in infancy, when compared with term-born control groups.

Data Sources

Eight databases searched up to December 2021.

Study Selection

Studies reporting spirometry for preterm-born participants with or without a term-born control group were identified.

Data Extraction and Synthesis

Data were extracted and quality assessed by 1 reviewer and checked by another. Data were pooled using random-effects models and analyzed using Review Manager and the R metafor package.

Main Outcomes and Measures

Deficits in %FEV1 between preterm-born and term groups. Associations between deficits in %FEV1 and year of birth, age, introduction of surfactant therapy, and geographical region of birth and residence were also assessed.

Results

From 16 856 titles, 685 full articles were screened: 86 with and without term-born control groups were included. Fifty studies with term controls were combined with the 36 studies from our previous systematic review, including 7094 preterm-born and 17 700 term-born participants. Of these studies, 45 included preterm-born children without BPD, 29 reported on BPD28 (supplemental oxygen dependency at 28 days), 26 reported on BPD36 (supplemental oxygen dependency at 36 weeks' postmenstrual age), and 86 included preterm-born participants. Compared with the term-born group, the group of all preterm-born participants (all preterm) had deficits of %FEV1 of -9.2%; those without BPD had deficits of -5.8%, and those with BPD had deficits of approximately -16% regardless of whether they had BPD28 or BPD36. As year of birth increased, there was a statistically significant narrowing of the difference in mean %FEV1 between the preterm- and term-born groups for the all preterm group and the 3 BPD groups but not for the preterm-born group without BPD. For the all BPD group, when compared with Scandinavia, North America and western Europe had deficits of -5.5% (95% CI, -10.7 to -0.3; P = .04) and -4.1% (95% CI, -8.8 to 0.5; P = .08), respectively.

Conclusions and Relevance

Values for the measure %FEV1 were reduced in preterm-born survivors. There were improvements in %FEV1 over recent years, but geographical region had an association with later %FEV1 for the BPD groups.

Intra-breath oscillometry for the evaluation of lung function in children and adolescents with a history of preterm birth

Objective:

To assess respiratory system impedance (Z_rs) and spirometric parameters in children and adolescents with and without a history of preterm birth.

Methods:

We evaluated a sample of 51 subjects between 11 and 14 years of age: 35 who had a history of preterm birth (preterm group) and 16 who had been born at term (full-term group). Lung function was measured by spirometry, spectral oscillometry, and intra-breath oscillometry.

Results:

Neither spirometry nor spectral oscillometry revealed any statistically significant differences between the preterm and full-term groups. However, intra-breath oscillometry demonstrated significant differences between the two groups in terms of the change in resistance, reactance at end-inspiration, and the change in reactance (p < 0.05 for all).

Conclusions:

Our findings suggest that abnormalities in Z_rs persist in children and adolescents with a history of preterm birth and that intra-breath oscillometry is more sensitive than is spectral oscillometry. Larger studies are needed in order to validate these findings and to explore the impact that birth weight and gestational age at birth have on Z_rs later in life.

Respiratory morbidity in very low birth weight infants through childhood and adolescence

OBJECTIVE

To describe the long-term (up to 18 years of age) respiratory outcomes of children and adolescents born at very low birth weight (VLBW; ≤1500 g) in comparison with that of children born >1500 g.

METHODS

An observational, longitudinal, retrospective study comparing VLBW infants with matched controls, registered at a large health maintenance organization in Israel. Pulmonary outcomes collected anonymously from the electronic medical files included respiratory illness diagnoses, purchased medications for respiratory problems, office visits with either a pediatric pulmonologist or cardiologist and composite respiratory morbidity combining all these parameters.

RESULTS

Our study included 5793 VLBW infants and 11,590 matched controls born between 1998 and 2012. The majority (99%) of VLBW infants were premature (born < 37 weeks' gestation), while 93% of controls were born at term. The composite respiratory morbidity was significantly higher in VLBW infants compared with controls in all age groups (relative risk [95% confidence interval]: 1 year: 1.22 [1.19-1.26], <2 years: 1.30 [1.27-1.34], 2-6 years: 1.29 [1.27-1.32], 6-12 years: 1.53 [1.47-1.59], 12-18 years: 1.46 [1.35-1.56]; respectively). Both VLBW infants and controls demonstrated a steady decline in the composite respiratory morbidity with aging. In VLBW infants, lower gestational age was associated with higher respiratory morbidity only until 2 years of age and the morbidity declined in each gestational age group until adolescence.

CONCLUSION

Our study confirmed a strong association between VLBW and pulmonary morbidity. The higher prevalence of respiratory composite morbidity in VLBW infants persists over the years until adolescence. The respiratory morbidity is most evident in the first year of life and declines afterward.

Reduced Lung Function at Preschool Age in Survivors of Very Low Birth Weight Preterm Infants

Background: Survivors of preterm birth are at risk of long-term respiratory consequences. The objective of this prospective study was to assess pulmonary function at preschool age of former very low birth weight (VLBW) preterm children. Methods: Lung function of children born preterm and term controls aged 5-6 years were assessed by spirometry. The results were converted to z-scores. A questionnaire regarding respiratory symptoms was completed. Associations to gestational age (GA), birth weight (BW), bronchopulmonary dysplasia (BPD), and perinatal factors were assessed. Results: In total, 85 VLBW preterm children and 29 term controls were studied. Of the preterm children, the mean GA was 28.6 ± 2.6 weeks and the mean BW was 1,047 ± 273 gm. Preterm children had significantly lower z-scores of forced expiratory volume in 1 s (FEV₁), FEV₁/forced vital capacity (FVC) ratio, and forced expiratory flow rate between 25-75% of FVC (FEF_25-75), compared with term controls (-0.73 vs. 0.04, p = 0.002; -0.22 vs. 0.39, p = 0.003; -0.93 vs. 0.0, p < 0.001; respectively). Further segregation of the preterm group revealed significantly impaired FEV₁, FEF_25-75 in children at earlier gestation (≤ 28 weeks, n = 45), lighter at birth (≤ 1,000 g, n = 38), or with BPD (n = 55) compared with term controls (p < 0.05). There were significant negative relationships between the severity of BPD with FEV₁, FVC, and FEF_25-75 (p < 0.05). However, no correlation between lung function measurements and respiratory symptoms was found. Conclusions: VLBW preterm infants have reduced lung function at preschool age, especially among those with younger GA, lower BW, and BPD. Additional long-term follow-up of respiratory outcomes are needed for this vulnerable population.

Leisure Time Physical Activity in Young Adults Born Preterm

OBJECTIVE

To evaluate the amount of self-reported physical activity in young adults born prematurely compared with those born at term.

STUDY DESIGN

Unimpaired participants of the Preterm Birth Study (Preterm Birth and Early Life Programming of Adult Health and Disease) birth cohort study were studied at age 23.3 ± 1.2 (SD) years: 118 born early preterm (<34 weeks), 210 late preterm (34-36 weeks), and 311 born at term (≥37 weeks, controls). The participants completed a validated 30-item, 12-month physical activity questionnaire. The annual frequency and total volume of conditioning and nonconditioning leisure time physical activity and commuting physical activity were calculated and the data analyzed by means of linear regression.

RESULTS

Adults born early preterm reported a 31.5% (95% CI, 17.4-43.2) lower volume of leisure time physical activity (in metabolic equivalents [MET] h/year) and had a 2.0-fold increased OR (1.2-3.3) of being in the least active quintile than controls. Lower amounts of conditioning, nonconditioning, and commuting physical activity all contributed to the difference. In addition, early preterm participants undertook less vigorous physical activity (≥6 MET). No differences in physical activity were found between the late preterm and control groups. Adjustments for potential early life confounders and current mediating health characteristics did not change the results.

CONCLUSIONS

Young adults born early preterm engage less in leisure time physical activities than peers born at term. This finding may in part underlie the increased risk factors of cardiometabolic and other noncommunicable diseases in adults born preterm. Low physical activity is a risk factor for several noncommunicable diseases and amenable to prevention.