Do parental heights influence pregnancy length?: a population-based prospective study, HUNT 2

Table 1 Associations of maternal and paternal covariates ¹ with pregnancy length ² assessed as differences in days

Prepregnancy parental covariate	Number of births	Difference in gestational length(days)	95% CI	P for trend
Maternal age at delivery (per 5-years)	4038	−0.5	−1.1, 0.0	0.04
Parity²				0.46
0	1107	0	Ref
1	1502	0.5	−0.5,1.5
2 or more	1429	−0.4	−1.4,0.7
Maternal education³				0.19
< 10 years	190	0	ref
10-12 years	2214	3.6	0.7,6.6
>12 years	1587	3.9	0.9,6.9
Maternal smoking⁴				0.01
no	2911	0	Ref
yes	1036	−0.6	−1.6,0.5
Maternal unemployment and /or receiving social benefits				0.28
No	3305	0	Ref
Yes	733	−1.1	−1.8,0.5
Maternal BMI(quintiles)				0.82
≤ 21.3	878	0	Ref
21.4-22.9	859	0.8
23.0-24.7	817	0.8
24.8-27.1	810	1.1
≥ 27.2	674	−0.1
Maternal systolic blood pressure, in mm Hg(quintiles)				0.002
< 111	863	0	Ref
112-117	838	−0.1	−1.4,1.2
118-122	712	−1.0	−2.4,0.3
123-130	862	−1.1	−2.5,0.2
>131	763	−2.0	−3.4,-0.6
Paternal age at delivery (per 5 years)	2153	−0.1	−0.7,0.6	0.85
Paternal BMI (quintiles)				0.55
≤ 22.9	388	0	Ref
23.0-24.3	436	2.2	0.3,4.1
24.4-25.8	445	1.2	−0.8,3.3
25.9-27.8	463	0.9	−1.2,2.9
≥ 27.9	421	0.1	−2.1,2.2
Paternal systolic blood pressure, in mm Hg (quintiles)				0.63
≤122	437	0	Ref
123-129	399	−1.3	−3.2,0.7
130-135	440	−0.3	−2.2,1.6
136-142	428	0.4	−1.5,2.3
≥143	449	−0.3	−2.1,1.5

¹Parental covariates were measured prior to pregnancy, at the HUNT 2 Study, Norway, 1995–1997. ²EDD (Expected Date of Delivery) estimated by ultrasound measurement in 17–19 weeks of gestation.³Parity = previous births. ⁴Missing data on educational status for 47 women. ⁵Missing data on smoking status for 91 women.

ISSN: 1471-2393