Maternal sleep and small for gestational age infants in the Japan Environment and Children’s Study: a cohort study

Table 1 Crude and adjusted risk ratios for sleep factors and birth weight

	No. of births	%	Missing data (n)	No. of non-SGA births	No. of SGA births	% SGA	Crude		Confounder-adjusted
	No. of births	%	Missing data (n)	No. of non-SGA births	No. of SGA births	% SGA	RR	95% CI	RR	95% CI
Hours of sleep
4–5.9	367	4.8	16	331	20	5.7	0.73	0.47–1.14	0.74	0.45–1.23
6–6.9	1242	16.1	68	1104	70	6.0	0.76	0.59–1.00	0.75	0.55–1.02
7–7.9^a	2545	33.0	146	2212	187	7.8			1
8–8.9	2205	28.6	113	1928	164	7.8	1.01	0.82–1.23	1.05	0.84–1.32
9–12	1349	17.5	74	1198	77	6.0	0.77	0.60–1.00	0.80	0.60–1.08
Missing	923		66	789	68
Tiredness upon waking
Bad	1970	23.3	102	1729	139	7.4	1.04	0.87–1.25	1.11	0.90–1.36
Good^a	6492	76.7	366	5688	438	7.1			1
Missing	169		15	145	9

ISSN: 1756-0500