Maggie is the English diminutive of Margaret — from the Greek margaron, meaning "pearl." The pet name has been used in English since the medieval period.
Maggie has been continuously in the U.S. top 500 since records began. The character Maggie Simpson (the baby of the family in The Simpsons), the singer Maggie Rogers, and the protagonist of The Mill on the Floss have all carried it. Today Maggie sits in the U.S. top 300 and is rising fast.
Maggie does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Maggie reduce to 6, The Nurturer. This is a traditional interpretive system, not a factual claim about the name.