Fig. 3
The main effect and interaction effect in age and regions. A The occurrence of abnormal foetal tissue chromosome karyotypes for 5 regions stratified byage. B The occurrence of abnormal foetal tissue chromosome karyotypes for < 35 and ≥ 35 years stratified by 5 regions. C The heatmap of main effect in age and regions. Red meant more abnormal foetal tissue chromosome karyotypes on the left than on the top. Blue meant the less on the left. One cell included mean difference value and pvalue. blank cells indicated that there was no significant interaction effectin age *region (p = 0.883)