Shanghai's first set of sex education textbooks has finished printing and will pilot in 18 primary schools this semester.

Many parents welcome the books and some non-local education bureaus have contacted the publisher, the Shanghai Education Publishing House, to purchase the books. But the editors have decided to slow the progress of the controversial trial.

The textbooks for pupils in grades one and two were removed from the shelves one day after their release last month, prompting suspicions that they were banned because of public opposition. The book editors said the printing house simply had released the books early by mistake.

The textbooks for students in grades three to six have just finished printing and are being sent to the children in the 18 primary schools.

The textbook is based on the sex education materials of the Primary School Affiliated to the University of Shanghai for Science and Technology.

Teachers in the piloted schools will receive training on how to teach the subject, and editors will make revisions to the book based on the pilot program.

Compared with the Beijing sex education textbook that has sparked controversy, the Shanghai version is tamer. It has replaced illustrations depicting intercourse with cartoon pictures of tadpoles.

In one chapter called "Where Do I Come From?" it introduces names of private parts and explains fertilization with colorful illustrations.

Xu Jing, one of the textbook's editors, said the books may be issued to the public after the trial stage.