Associations between maternal age at menarche and occurrence of atopy in children at 31 years
| Maternal age at menarche (years) | Total no. (atopics) | % | Crude OR (95% CI) | Adjusted OR1-150 (95% CI) |
| Total | ||||
| ⩽12 | 694 (242) | 34.9 | 1.49 (1.19 to 1.87) | 1.43 (1.12 to 1.83) |
| 13 | 1181 (387) | 32.8 | 1.36 (1.11 to 1.66) | 1.29 (1.03 to 1.60) |
| 14 | 1406 (424) | 30.2 | 1.21 (0.99 to 1.47) | 1.15 (0.93 to 1.42) |
| 15 | 1145 (344) | 30.0 | 1.20 (0.98 to 1.47) | 1.19 (0.95 to 1.48) |
| ⩾16 | 762 (201) | 26.4 | 1.00 | 1.00 |
| p for trend | 0.000 | 0.005 | ||
| Men | ||||
| ⩽12 | 347 (133) | 38.3 | 1.44 (1.06 to 1.96) | 1.32 (0.94 to 1.86) |
| 13 | 593 (215) | 36.3 | 1.32 (1.00 to 1.74) | 1.19 (0.88 to 1.62) |
| 14 | 710 (231) | 32.5 | 1.12 (0.86 to 1.47) | 1.08 (0.81 to 1.45) |
| 15 | 566 (171) | 30.2 | 1.01 (0.76 to 1.33) | 0.96 (0.71 to 1.31) |
| ⩾16 | 382 (115) | 30.1 | 1.00 | 1.00 |
| p for trend | 0.002 | 0.048 | ||
| Women | ||||
| ⩽12 | 347 (109) | 31.4 | 1.57 (1.13 to 2.18) | 1.58 (1.10 to 2.26) |
| 13 | 588 (172) | 29.3 | 1.41 (1.05 to 1.91) | 1.40 (1.01 to 1.93) |
| 14 | 696 (193) | 27.7 | 1.31 (0.98 to 1.76) | 1.24 (0.90 to 1.70) |
| 15 | 579 (173) | 29.9 | 1.46 (1.08 to 1.96) | 1.47 (1.07 to 2.02) |
| ⩾16 | 380 (86) | 22.6 | 1.00 | 1.00 |
| p for trend | 0.034 | 0.149 |
↵1-150 Adjusted variables were defined in the following ways: maternal age ⩽20, 21–25, 26–30, 31–35, and ⩾36 years; maternal social classes I + II (professionals with the highest education and other white collar workers), III (skilled workers), IV (unskilled workers) and farmers; maternal smoking in pregnancy yes or no; parity 0, 1, 2–3 and ⩾4; seasons at birth March–May, June–August, September–November and December–February; parental allergy yes if either the father or mother had allergic disorders, otherwise no; current vocational training in five categories; maternal BMI, ponderal index and current BMI in quintiles.