Anna Kournikova & Enrique Iglesias Have Twins After Super Private Pregnancy

Anna Kournikova and Enrique Iglesias are first-time parents -- she gave birth to twins over the weekend ... TMZ has learned, but the real miracle is ... no one had a clue she was pregnant!

Sources in Miami tell us Anna had a boy and a girl Saturday in Miami, and their names are Nicholas and Lucy. The only thing overshadowing the blessed occasion is the fact they kept this whole thing a secret for 9 months.

Fact is ... Anna's been way out of the spotlight for more than a year now. The last photo we can find of the 36-year-old in public is this shot on a boat in Miami ... from November 2016.

This is definitely their M.O. -- the couple's always been super private.

They've been together since 2001, and although there have been marriage rumors for years -- fueled by a HUGE rock on her hand -- neither's ever confirmed it.

Congrats to the fam ... and welcome to MILF-dom, Anna!