Table 5.

Mean differences in length of pregnancy by paternal height¹

		Difference in pregnancy length (days)
		Crude estimate2	Adjusted for obstetric and socioeconomic factors3			Additional adjustment for maternal cardiovascular risk factors4
Paternal height (in quintiles)	N	Mean difference	Mean difference	95% CI	p for trend	Mean difference	95% CI	p for trend
Estimated date of delivery based on US
≤ 175	503	0	0	Ref		0	Ref
176-178	397	0.2	−0.2	−2.0,1.7		−0.5	−2.4,1.4
179-181	448	−0.1	−0.6	−2.4,1.3		−0.8	−2.6,1.1
182-185	412	0.6	−0.5	−2.2,1.6		−0.8	−2.7,1.1
≥186	399	0.5	−0.7	−2.5,1.0	0.43	−0.7	−2.5,1.0	0.39
Estimated date of delivery based on LMP
≤ 175	642	0	0	Ref		0	Ref
176-178	496	0.2	0.0	−1.9,1.9		−0.2	−2.0,1.7
179-181	514	0.2	−0.1	−1.9,1.6		−0.3	−2.0,1.5
182-185	552	−0.6	−1.2	−3.0,0.7		−1.4	−3.2,0.5
≥186	512	−0.3	−0.9	−2.7,0.9	0.17	−0.9	−2.7,0.9	0.16

¹Pregnancy length according to date of delivery estimated by ultrasound (US) (2159 pregnancies) and by first day of last menstrual period (LMP) (2716 pregnancies). ²Adjusted for paternal age at baseline (HUNT 2 participation). ³Additionally adjusted for maternal height, maternal age at birth, duration between Hunt 2 participation and delivery, maternal education, parity, maternal smoking, receiving social security benefits or not, and fetal sex. ⁴Additionally adjusted for pre-pregnancy hypertension, diabetes mellitus, kidney and heart disease, BMI; systolic and diastolic blood pressure, concentration of glucose and lipids and maternal height.