Table 2.

The average score of stress between the two intervention and control groups

Stress	Control	Intervention	Average treatment effect*	95% CI for difference**
Total stress	2.74±0.79	1.71±0.79	1.18	0.93-1.44
Stress over the NICU environment	3.2±0.95	1.77±0.85	1.47	1.19-1.75
Stress over the appearance, behavior, and treatment of infant	2.41±0.92	1.47±0.97	1.06	0.73-1.14
Stress over parental role alteration	3.01±0.91	2.05±0.93	1.21	0.93-1.49

*Average treatment effect is adjusted for infant’s disease intensity, birth age, birth weight, reception status anxiety, and reception trait anxiety using the inverse probability treatment weight method. **It is significant if the confidence interval not including the zero