Afterward she gave birth to a daughter, and named her Dinah.
Genesis 30:21 (NASB)
Of Rachel and Leah’s children in Genesis 30, Dinah is the only girl. While this is notable, the rabbis also notice that Dinah is the only child for whom the phrase “and she conceived” is omitted.
One possible reason is that Dinah is Zebulun’s twin sister, and that the conception mentioned in verse 19 covers both siblings.
Also notable: Dinah’s name is not explained. It means “judgement.”