Table 3.

Sleep behaviors and parenting practices at 16 weeks among firstborn (FB) and secondborn (SB) siblings enrolled in the INSIGHT and SIBSIGHT studies (n=107 dyads

	FB	SB	Similarity within families		Birth order effect SB vs. FBa
Variables	%	%	% agreement	Fisher’s exact test p-value	OR	95% CI	p-value
Bedtime routine, %
Duration >15-≤45 minb	42	43	64	0.009	1.1	0.7–1.8	0.71
Components
Read book	45	25	64	0.01	0.4	0.2–0.7	<0.001
Rocking	63	58	73	<0.001	0.8	0.5–1.3	0.35
Bath	61	49	67	<0.001	0.6	0.4–0.9	0.03
Music	19	14	82	0.001	0.7	0.4–1.3	0.25
Watch television	9	2	89	1.00	0.2	0.0–0.9	0.04
Bottle feed/breastfeed	94	94	88	1.00	1.2	0.4–3.8	0.78
Fed as last activity	35	26	73	<0.001	0.7	0.4–1.1	0.10
Sleep location and behaviors, %
Bedtime 8PM or earlier	32	38	69	0.001	1.4	0.8–2.3	0.23
Sleeps in own room	65	51	75	<0.001	0.6	0.4–0.8	0.004
Falls asleep swaddled	28	33	69	0.006	1.3	0.7–2.1	0.39
Falls asleep with pacifier	36	27	71	0.001	0.7	0.4–1.1	0.11
Falls asleep with white noise	30	35	71	<0.001	1.2	0.8–2.0	0.35
Falls asleep being held	45	43	70	<0.001	0.9	0.6–1.4	0.72
Falls asleep alone in room, in crib (self-soothes)	46	37	71	<0.001	0.7	0.4–1.1	0.11
Falls asleep in ≤15 min	63	66	55	0.84	1.2	0.7–2.1	0.56
Night waking, %
≥ 2 per night	33	41	62	0.06	1.4	0.9–2.4	0.16
≥ 2 night feedingsc	31	37	64	0.05	1.3	0.8–2.2	0.33
Parenting strategies
Give a few minutes to fall back asleep	58	50	67	<0.001	0.7	0.5–1.1	0.13
Pick up and hold/rock back to sleep	34	34	66	0.02	1.0	0.6–1.7	1.00
Rub/pat but do not pick up	19	20	77	0.02	1.1	0.6–1.9	0.84
Feed back to sleep	65	65	70	<0.001	1.0	0.6–1.6	1.00
Give pacifier	37	40	69	<0.001	1.1	0.7–1.8	0.60
Change diaper	68	59	61	0.10	0.7	0.4–1.1	0.12
Sleep safety, %
Supine position	91	89	91	<0.001	0.8	0.4–1.5	0.53
Unapproved object in crib (e.g., blanket, pillow)d	42	29	70	<0.001	0.6	0.4–0.9	0.02

^aOR and P value from generalized linear mixed model controlling for study group;

^bn=106 dyads;

^cn=105 dyads;

^dn=103 dyads;