Age adjusted prevalence of coronary heart disease and age adjusted means and prevalences of coronary heart disease risk factors by season of birth
| Summer June 21 to Sept 22 (n = 1120) | Autumn Sept 23 to Dec 21 (n = 1007) | Winter Dec 22 to March 20 (n = 1042) | Spring March 21 to June 20 (n = 1117) | Difference between seasons of birth (p value) | |
|---|---|---|---|---|---|
| Values are mean (95% confidence interval). | |||||
| *Geometric mean. | |||||
| BMI, body mass index; CHD, coronary heart disease; FEV1, forced expiratory volume in one second; HDLC, high density lipoprotein cholesterol; LDLC, low density lipoprotein cholesterol. | |||||
| CHD (%) | 15.2 (13.2 to 17.5) | 15.0 (12.9 to 17.3) | 19.8 (17.5 to 22.3) | 15.2 (13.2 to 17.4) | 0.008 |
| Metabolic risk factors | |||||
| Systolic blood pressure (mm Hg) | 147.6 (146.1 to 149.2) | 147.4 (145.8 to 149.0) | 147.4 (145.8 to 149.0) | 146.1 (144. 6 to 147.6) | 0.51 |
| Diastolic blood pressure (mm Hg) | 79.6 (78.9 to 80.4) | 79.6 (78.9 to 80.4) | 79.5 (78.8 to 80.3) | 78.9 (78.2 to 79.6) | 0.47 |
| LDLC (mmol/l) | 4.17 (4.10 to 4.24) | 4.17 (4.10 to 4.24) | 4.11 (4.04 to 4.18) | 4.12 (4.07 to 4.19) | 0.56 |
| HDLC (mmol/l) | 1.66 (1.63 to 1.68) | 1.64 (1.61 to 1.66) | 1.66 (1.63 to 1.69) | 1.67 (1.64 to 1.70) | 0.37 |
| Triglycerides (mmol/l)* | 1.65 (1.60 to 1.70) | 1.68 (1.63 to 1.73) | 1.68 (1.63 to 1.73) | 1.66 (1.62 to 1.72) | 0.69 |
| Insulin resistance (HOMA score)* | 1.65 (1.58 to 1.72) | 1.62 (1.54 to 1.68) | 1.68 (1.60 to 1.75) | 1.72 (1.65 to 1.79) | 0.15 |
| Diabetes (%) | 6.9 (5.5 to 8.7) | 8.7 (7.0 to 10.7) | 6.8 (5.4 to 8.6) | 6.7 (5.3 to 8.4) | 0.28 |
| Anthropometric measures | |||||
| Birth weight (kg) | 3.29 (3.21 to 3.37) | 3.29 (3.21 to 3.38) | 3.21 (3.12 to 3.29) | 3.33 (3.25 to 3.41) | 0.17 |
| Offspring birth weight (kg) | 3.22 (3.18 to 3.25) | 3.24 (3.20 to 3.28) | 3.26 (3.22 to 3.29) | 3.25 (3.22 to 3.29) | 0.42 |
| Weight (kg) | 69.0 (68.2 to 69.8) | 69.5 (68.7 to 70.3) | 69.5 (68.7 to 70.3) | 70.3 (69.5 to 71.1) | 0.62 |
| BMI (kg/m2) | 27.5 (27.2 to 27.8) | 27.5 (27.2 to 27.8) | 27.6 (27.3 to 27.9) | 27.9 (27.6 to 28.2) | 0.31 |
| Obese (BMI >30 kg/m2) (%) | 25.7 (23.2 to 28.5) | 25.2 (22.6 to 28.1) | 26.8 (24.1 to 29.7) | 28.0 (25.4 to 30.9) | 0.48 |
| Waist–hip ratio | 0.817 (0.813 to 0.821) | 0.820 (0.816 to 0.825) | 0.820 (0.815 to 0.824) | 0.819 (0.814 to 0.823) | 0.77 |
| Height (m) | 1.582 (1.579 to 1.586) | 1.590 (1.586 to 1.594) | 1.587 (1.584 to 1.592) | 1.586 (1.582 to 1.590) | 0.10 |
| Leg length (m) | 0.755 (0.752 to 0.758) | 0.759 (0.756 to 0.762) | 0.759 (0.756 to 0.761) | 0.757 (0.754 to 0.759) | 0.07 |
| Trunk length (m) | 0.829 (0.827 to 0.831) | 0.832 (0.830 to 0.834) | 0.829 (0.826 to 0.831) | 0.832 (0.829 to 0.834) | 0.15 |
| Smoking and lung function | |||||
| Ever smoked (%) | 43.8 (40.9 to 46.7) | 42.9 (39.8 to 46.0) | 44.2 (41.2 to 47.3) | 46.9 (43.9 to 49.8) | 0.28 |
| Current smoker (%) | 11.4 (9.7 to 13.4) | 11.3 (9.5 to 13.4) | 10.9 (9.2 to 13.0) | 12.8 (10.9 to 15.0) | 0.55 |
| FEV1 (l) | 1.97 (1.94 to 2.00) | 1.99 (1.96 to 2.02) | 1.95 (1.92 to 1.98) | 1.97 (1.94 to 2.00) | 0.09 |
| Social class and education | |||||
| Adult manual social class (%) | 51.0 (47.8 to 54.1) | 50.7 (47.4 to 54.0) | 51.8 (48.6 to 55.1) | 52.8 (50.0 to 55.9) | 0.80 |
| Childhood manual social class (%) | 77.1 (74.3 to 79.6) | 76.8 (73.9 to 79.5) | 77.7 (74.8 to 80.3) | 75.3 (72.5 to 77.9) | 0.67 |
| Age at completion of full time education (years) | 15.9 (15.7 to 16.2) | 15.7 (15.5 to 16.0) | 15.6 (15.3 to 15.8) | 15.9 (15.6 to 16.1) | 0.23 |