Table 1 Number, age, gender, and reasons for exclusion of study participants in each daycare group and in total.

Each child spent daily (Monday to Friday) approximately 1.5 hours outdoors.

Intervention*
4 centers
Standard
3 centers
Nature
3 centers
Total children
10 centers
Total children36162375
  Boys1891037
  Girls1871338
Age§4.3 ± 0.64.9 ± 0.34.7 ± 0.54.6 ± 0.6
Excluded
  Antibiotic users2103
  Probiotic users1012
  Medication users3238

*Children in intervention daycare centers.

†Children in standard, nonmodified daycare centers.

‡Children in nature-oriented daycare centers where children visited boreal forests on a daily basis.

§Age is presented as means±SD.

║Children using probiotics, antibiotics, or medication (paracetamol, desloratadine, pyrvin, cetirizine, and salbutamol) were excluded from the gut microbiome and cytokine analyses. One child with pinworm infection was excluded from all analyses.