Fig. 2

Patients diagnosed with bilateral inguinal hernias. A Quadratic relationship for male bilateral hernias per year in the first year of life [12 (95% confidence interval: 9–15, P = 0.002)] and decreasing numbers of patients in the age groups between one and four [5 (95% confidence interval: 2–7, P = 0.001)] as well as between 5 and 9 years [2 (95% confidence interval: 1–3, P = 0.0023)] over time, whereas there was no difference in the age group between 10 and 14 years [0.6 (95% confidence interval: 0.1–1.4, P = 0.0957)]. B Decreasing numbers of female bilateral inguinal hernias per year in the first year of life [5 (95% confidence interval: 4–6, P < 0.0001)] and in patients aged between 5 and 9 years [1.4 (95% confidence interval: 0.03–2.7, P = 0.0453)]. The numbers did not change for the other two age groups [1–4: 1.3 (95% confidence interval: − 3–0.3, P = 0.1041); 10–14: 0.6 (95% confidence interval: − 1.2–0.007, P = 0.0521)]. C Decreasing numbers of male bilateral incarcerated hernias per year in the age groups between one and four [0.2 (95% confidence interval: 0.04–0.4, P = 0.0219)] and also in that between 5 and 9 years of age [0.2 (95% confidence interval: 0.04–0.4, P = 0.0228)], whereas the number did not change for the two other age groups [< 1: 0.2 (95% confidence interval: − 1.3–1.7, P = 0.781); 10–14: 0.03 (95% confidence interval: − 0.1–0.2, P = 0.585)]. D Increasing numbers of female bilateral incarcerated inguinal hernias per year in the first year of life [1 (95% confidence interval: 0.2–1.8, P = 0.0235)], whereas the numbers remained similar in the other age groups [1–4: 0.03 (95% confidence interval: − 0.2–0.3, P = 0.792; 5–9: 0.05 (95% confidence interval: − 0.1–0.2, P = 0.546); 10–14: − 0.05 (95% confidence interval: − 0.15–0.06, P = 0.369)]. All data was analysed using ordinary least squares regression except for bilateral incarcerated inguinal hernias in males aged between five and nine years as well as for female bilateral inguinal hernias in the age group between one and four years