Check here mum-https://community.theasianparent.com/q/any-mummies-know-dimension-lo-health-booklet-i-wanted-get-cover-from-popular-bookstore-but-there-lot-different-sizes-ive-keep-forgetting-bring-health-booklet-out-which-size-should-i-getthank/7684
Try checking with the hospital baby was born in?
You may try to call or email to the hospital