Table 2.

Identifying insomnia and cognitive arousal factors associated with perinatal depression using linear and logit mixed effects modeling

Model 1, Predicting depression symptoms: Wald χ 2 = 144.25, p < 0.001 (obs = 1,051)
	b	95% CI	z	p
Interindividual factors
Prior miscarriage	−0.90	−2.76 to 0.96	−0.94	0.345
Age	−0.03	−0.21 to 0.15	−0.36	0.716
Poverty	−1.64	−3.73 to 0.46	−1.53	0.125
BMI ≥35	−1.08	−3.27 to 1.11	−0.97	0.333
Snoring	2.64	0.80 to 4.49	2.81	0.005
EPDS ≥10	3.81	2.34 to 5.29	5.07	<0.001
ISI ≥10	0.18	−0.65 to 1.01	0.43	0.667
Short sleep (≤6 h/night)	0.56	−1.14 to 2.25	0.64	0.519
PSASC ≥20	1.51	0.02 to 3.00	1.99	0.046
PFR ≥3	2.00	0.52 to 3.47	2.66	0.008
Intraindividual factors
Time	2.44	−0.26 to −0.13	−6.03	<0.001
Prenatal vs Postpartum	0.75	0.09 to 1.40	2.24	0.025
Model 2, Predicting depression symptoms: Wald χ 2 = 541.81, p < 0.001 (obs = 1,130)
	b	95% CI	z	p
Interindividual factors
Snoring	0.88	−0.16 to 1.93	1.66	0.096
EPDS ≥10	1.86	0.98 to 2.74	4.15	<0.001
PSASC ≥20	0.13	−0.69 to 0.95	0.30	0.761
PFR ≥3	0.75	−0.05 to 1.54	1.84	0.066
Intraindividual factors
Time	−0.09	−0.15 to −0.04	−3.54	<0.001
Prenatal vs Postpartum	0.70	0.15 to 1.26	2.48	0.013
ISI	0.12	0.07 to 0.16	5.10	<0.001
Sleep duration	0.03	−0.13 to 0.18	0.36	0.717
PSASC	0.09	0.04 to 0.13	3.68	<0.001
PFR	0.33	0.16 to 0.51	3.68	<0.001
PTQ	0.17	0.14 to 0.19	14.44	<0.001
Model 3, Predicting positive depression status: Wald χ 2 = 128.83, p < 0.001 (obs = 1,130)
	OR	95% CI	z	p
Interindividual factors
Snoring	0.84	—	−0.26	0.791
EPDS ≥10	13.85	4.27 to 44.93	4.38	<0.001
PSASC ≥20	1.12	—	0.20	0.844
PFR ≥3	2.04	—	1.35	0.178
Intraindividual factors
Time	0.91	0.83 to 0.99	−2.04	0.041
Prenatal vs Postpartum	1.68	—	1.12	0.264
ISI ≥10	2.36	1.28 to 4.35	2.76	0.006
PSASC ≥20	3.05	1.60 to 5.79	4.03	<0.001
PFR ≥3	2.05	1.11 to 3.79	2.30	0.021
PTQ ≥10	7.48	3.90 to 14.32	6.06	<0.001

The Wald χ ² statistic reflects the difference between the tested model and a null model with no predictors. Thus, a significant χ ² is desirable as it indicates a model that accounts for significant variance in the outcome. obs = observations; b = unstandardized parameter estimate; SE = standard error; 95% CI = 95% confidence interval; z = z-statistic; p = significance value. Interindividual factors were recorded at the study baseline, and significant effects represent between-subject differences. Intraindividual factors were recorded weekly across peripartum, and significant effects represent within-subject associations. Age represents age in years reported at baseline. Poverty was operationalized as less than $20,000 of annual household income. BMI = body mass index; BMI ≥ 35 represents obesity class II. Snoring was recorded at study entry (Yes = 1, No = 0). EPDS = Edinburgh postnatal depression scale, scores 10 and higher indicate probable minor or major depression. ISI = Insomnia Severity Index, scores 10 and higher indicate clinically significant symptoms. Short sleep operationalized as averaging ≤6 h per night over the prior month. Time represents study week. Prenatal vs Postpartum coded as prenatal = 0 and postpartum = 1. ISI as an intraindividual factor represents insomnia symptom severity over the prior week. Sleep duration as an intraindividual factor represents the average nightly sleep duration over the prior week. PSASC as an interindividual factor represents trait nocturnal cognitive arousal; scores of 20 and higher indicate high nocturnal cognitive arousal. PSASC as an intraindividual factor represents nocturnal cognitive arousal over the prior week. PFR represents nocturnal perinatal-focused rumination; scores of 3 and higher indicate high perinatal-focused rumination. PFR as an intraindividual factor represents nocturnal perinatal-focused rumination over the prior week. PTQ represents perseverative thinking over the prior week; scores of 10 and higher indicate elevated perseverative thinking levels.