Table 1

Associations of maternal and paternal covariates1 with pregnancy length2 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.

Myklestad et al.

Myklestad et al. BMC Pregnancy and Childbirth 2013 13:33   doi:10.1186/1471-2393-13-33

Open Data