hyphens: pre-, post-

In most instances, a hyphen is not needed to connect the prefixes pre- and post- to words.

• Samantha and Rick attended prenatal classes before the birth of their first child.
• Enrolling in postsecondary education can lead to a brighter future.

However, a hyphen is used in the following cases:

• when the root word starts with a capital:
  • The museum has many trilobites in its Pre-Cambrian fossil collection.
  • Is this an example of pre- or post-World War II architecture?
• when the root word begins with the same letter as the last letter in the prefix:
  • Dr. Keon is a pre-eminent heart surgeon.
  • Some veterans experience post-traumatic stress disorder.
• when you add post or pre to a compound:
  • Pre-nineteenth-century art focussed mainly on religious themes.
  • Applicants taking part in the literacy test were given pre‑high school texts to read.
• when you connect pre or post to numbers:
  • Current fashions mimic pre-1980s styles.
  • The exhibit focussed on the artist’s post-1920s drawings and lithographs.