Table 2 Means of coronary heart disease (CHD) risk factors at 53 years by parental age at birth of first child and regression coefficients representing mean change in risk factor per year increase in parental age at birth of first child
OutcomeNAge at birth of first childp ValueAge (years) at birth of first child as a continuous variable
<20 years20–24 years25–29 years⩾30 years
Mean (95% CI)Mean (95% CI)Mean (95% CI)Mean (95% CI)TrendSex int.*Regression coefficient† (95% CI)p Value
BMI (kg/m2)0.5
    Women131128.0 (27.2 to 28.8)27.8 (27.3 to 28.2)27.1 (26.5 to 27.6)26.8 (25.9 to 27.7)0.006−0.08 (−0.15 to −0.01)0.02
    Men120628.5 (27.3 to 29.8)28.2 (27.8 to 28.6)27.2 (26.9 to 27.6)27.1 (26.7 to 27.6)<0.001−0.08 (−0.13 to −0.04)<0.001
Waist–hip ratio (%)0.9
    Women131881.8 (80.8 to 82.7)80.7 (80.2 to 81.3)80.2 (79.6 to 80.8)80.4 (79.4 to 81.5)0.02−0.09 (−0.18 to −0.01)0.02
    Men120595.1 (93.2 to 97.0)94.6 (94.0 to 95.3)93.2 (92.6 to 93.7)93.1 (92.4 to 93.8)0.001−0.13 (−0.20 to −0.07)<0.001
SBP (mmHg)0.6
    Women1299138.5 (135.2 to 141.8)136.6 (134.8 to 138.3)132.8 (130.6 to 134.9)131.0 (127.4 to 134.6)<0.001−0.58 (−0.86 to −0.31)0.001
    Men1202149.5 (142.9 to 156.1)144.0 (141.8 to 146.1)140.0 (138.2 to 141.9)140.6 (138.1 to 143.2)0.003−0.31 (−0.54 to −0.08)0.008
DBP (mmHg)0.6
    Women129984.9 (83.0 to 86.9)83.7 (82.7 to 84.8)82.2 (80.9 to 83.4)82.0 (79.9 to 84.0)0.006−0.23 (−0.39 to −0.08)0.004
    Men120291.4 (87.3 to 95.5)90.3 (89.0 to 91.7)87.5 (86.3 to 88.7)87.7 (86.1 to 89.2)0.002−0.21 (−0.35 to −0.06)0.005
TC (mmol/l)0.5
    Women11346.12 (5.94 to 6.29)6.18 (6.08 to 6.27)6.12 (6.00 to 6.23)6.10 (5.91 to 6.30)0.6−0.001 (−0.02 to 0.01)0.9
    Men10676.04 (5.68 to 6.39)6.09 (5.97 to 6.20)6.12 (6.02 to 6.23)6.11 (5.97 to 6.25)0.70.001 (−0.01 to 0.01)0.8
LDL-C (mmol/l)0.6
    Women10893.56 (3.40 to 3.72)3.54 (3.46 to 3.63)3.49 (3.38 to 3.60)3.43 (3.25 to 3.61)0.2−0.005 (−0.02 to 0.009)0.5
    Men9453.57 (3.25 to 3.89)3.62 (3.52 to 3.73)3.62 (3.53 to 3.72)3.56 (3.44 to 3.69)0.6−0.003 (−0.01 to 0.009)0.6
HDL-C (mmol/l)0.2
    Women10921.72 (1.64 to 1.79)1.83 (1.79 to 1.87)1.89 (1.83 to 1.94)1.89 (1.80 to 1.98)0.0010.009 (0.002 to 0.02)0.01
    Men9511.55 (1.41 to 1.70)1.45 (1.40 to 1.49)1.51 (1.47 to 1.55)1.52 (1.46 to 1.57)0.10.005 (0.00 to 0.01)0.05
Triglycerides (mmol/l)‡
    Women11331.68 (1.54 to 1.82)1.59 (1.52 to 1.66)1.45 (1.37 to 1.53)1.52 (1.38 to 1.67)0.0081.0−0.83 (−1.6 to −0.11)0.02
    Men10652.10 (1.73 to 2.55)2.25 (2.11 to 2.40)2.10 (1.99 to 2.22)2.00 (1.86 to 2.16)0.03−1.05 (−1.7 to −0.36)0.003
HbA1c (%)‡0.2
    Women11405.64 (5.54 to 5.73)5.65 (5.60 to 5.70)5.59 (5.53 to 5.66)5.59 (5.49 to 5.70)0.2−0.14 (−0.28 to 0.004)0.06
    Men10765.75 (5.57 to 5.93)5.68 (5.62 to 5.74)5.59 (5.54 to 5.64)5.57 (5.50 to 5.64)0.003−0.13 (−0.24 to −0.01)0.03
  • *p Value for interaction between sex and age at birth of first child.

  • †Regression coefficient represents mean change in CHD risk factor per year increase in parental age at birth of first child.

  • ‡Geometric means with their 95% CIs and for regression model outcomes transformed using 100×loge so that regression coefficient represents the per cent change in outcome per year of age at birth of first child.

  • BMI, body mass index; DBP, diastolic blood pressure; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; SBP, systolic blood pressure; TC, total cholesterol.