Table 4. “Regularity” measured with the Baby Behavior Questionnaire.

BBQ Regularity
Month	1	6	12
Mean	2.7	3.6	3.9
SD	0.9	0.7	0.6
Difference in p-value		0.000*	0.000**

*P-value for difference between month one and six corrected age.

**P-value for difference between month six and twelve corrected age. Scale 1–5 where increased numbers represent increased regularity.

Standard deviation (SD), Baby Behavior Questionnaire (BBQ).