Partly controlled or uncontrolled asthma in preschoolers may be linked with children’s early-life exposures and maternal perinatal factors, as well as to environmental factors, according to study findings published in BMJ Open Respiratory Research.
Previous studies show children with poor asthma control within 2 years of diagnosis are significantly more likely to have poor control in adolescence and less likely to experience remission. Investigators therefore sought to assess associations between the control of asthma in preschoolers and perinatal and early-life influences.
The investigators conducted a population-based, retrospective cohort study using administrative health data from 7206 mothers and children (born 2010-2012) in Alberta, Canada with an asthma diagnosis before 5 years of age (all children had at least 1 hospitalization for asthma or at least 2 medical claims for asthma between 15 days and 2 years apart). Within the cohort, asthma was present in more boys (64.4%) than girls.
Follow-up data was collected until 2019. Children diagnosed with cystic fibrosis or with records with missing linkages were excluded.
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Maternal perinatal and early-life factors including antibiotics in pregnancy and childhood, gestational diabetes, prenatal smoking, C-section and summertime birth, and hospitalizations for respiratory illness are associated with partly or uncontrolled childhood asthma.
Participating children’s level of asthma control was determined using the Pharmacoepidemiologic Pediatric Asthma Control Index (PPACI), which takes into account prescriptions fulfillment information for short-acting beta-agonists (SABA) and oral corticosteroids (OCS), emergency department (ED) visits and hospitalizations for asthma. Children were categorized as having: (1) well-controlled asthma (less than 4 SABA doses/week and no OCS, ED visits, or hospital admissions); (2) partly controlled asthma (at least 4 and no more than 6 SABA doses/week, and no OCS, ED, or hospital admissions); (3) poorly controlled asthma (at least 7 SABA doses/week or at least 1 OCS or at least 1 ED visit but no hospital admission); or (4) very poorly controlled asthma (at least 1 hospital admission for asthma).
Using the PPACI definitions, the investigators found that among the preschoolers, 2 years after diagnosis: 52% had controlled asthma, 37% had partly controlled asthma, and 12% had uncontrolled asthma.
Overall, 8.6% of child-mother dyads reported history of asthma and 17.2% reported history of atopic disease. With respect to maternal and birth factors, investigators noted that more than 31% of mothers reported antibiotic use during pregnancy and 17% reported smoking during pregnancy; gestational diabetes was reported in 6.5% of mothers; 68.2% of the children were born vaginally; and births were distributed evenly among the seasons.
Risk for partly controlled asthma vs controlled asthma increased with early-life hospitalization for respiratory illness (adjusted risk ratio [aRR], 2.24; 95% CI, 1.81-2.76), prenatal antibiotics (aRR, 1.19; 95% CI, 1.06-1.33), smoking (aRR, 1.18; 95% CI, 1.02-1.37), summer birth (aRR, 1.16; 95% CI, 1.00-1.34), and C-section delivery (aRR, 1.11; 95% CI, 1.00-1.25).
The investigators found risk for uncontrolled asthma vs controlled asthma increased with hospitalization for respiratory illness (aRR, 1.65; 95% CI, 1.19-2.27), gestational diabetes (aRR, 1.41; 95% CI, 1.06-1.87), antibiotics (aRR, 1.32; 95% CI, 1.08-1.61), and C-section delivery (aRR, 1.18; 95% CI, 1.00-1.39).
Study limitations include unavailable data on variables linked to asthma development (maternal body composition during pregnancy, childhood weight, breastfeeding).
“Maternal perinatal and early-life factors including antibiotics in pregnancy and childhood, gestational diabetes, prenatal smoking, C-section and summertime birth, and hospitalizations for respiratory illness are associated with partly or uncontrolled childhood asthma,” the investigators concluded. “These findings suggest that poor asthma control in childhood may in part be connected to alterations in the infant development brought on by perinatal events and exposures and/or influenced by environmental interactions during the early years,” said the study authors.
