Background: Preterm birth, low birth weight, and infant catch-up growth
seem associated with an increased risk of respiratory diseases in later
life, but individual studies showed conflicting results. Objectives: We
performed an individual participant data meta-analysis for 147,252
children of 31 birth cohort studies to determine the associations of
birth and infant growth characteristics with the risks of preschool
wheezing (1-4 years) and school-age asthma (5-10 years).
Methods: First, we performed an adjusted 1-stage random-effect
meta-analysis to assess the combined associations of gestational age,
birth weight, and infant weight gain with childhood asthma. Second, we
performed an adjusted 2-stage random-effect meta-analysis to assess the
associations of preterm birth (gestational age < 37 weeks) and low birth
weight (< 2500 g) with childhood asthma outcomes.
Results: Younger gestational age at birth and higher infant weight gain
were independently associated with higher risks of preschool wheezing
and school-age asthma (P <. 05). The inverse associations of birth
weight with childhood asthma were explained by gestational age at birth.
Compared with term-born children with normal infant weight gain, we
observed the highest risks of school-age asthma in children born preterm
with high infant weight gain (odds ratio [OR], 4.47; 95% CI,
2.58-7.76). Preterm birth was positively associated with an increased
risk of preschool wheezing (pooled odds ratio [pOR], 1.34; 95% CI,
1.25-1.43) and school-age asthma (pOR, 1.40; 95% CI, 1.18-1.67)
independent of birth weight. Weaker effect estimates were observed for
the associations of low birth weight adjusted for gestational age at
birth with preschool wheezing (pOR, 1.10; 95% CI, 1.00-1.21) and
school-age asthma (pOR, 1.13; 95% CI, 1.01-1.27).
Conclusion: Younger gestational age at birth and higher infant weight
gain were associated with childhood asthma outcomes. The associations of
lower birth weight with childhood asthma were largely explained by
gestational age at birth
