May 4 (UPI) -- Anna Kournikova gave fans a first glimpse of her baby bump in a throwback Instagram post.
The 36-year-old former tennis pro shared a pregnancy photo Thursday after welcoming twins, son Nicholas and daughter Lucy, with husband Enrique Igelsias.
Kournikova, who kept her pregnancy secret from the public, posted a picture of herself at 37 weeks pregnant. The snapshot shows the star striking a pose as she cradles her baby bump.
"#tbt #37weeks," she captioned the post.
Kournikova quietly gave birth to Nicholas and Lucy in December, and shared the first photos of the pair the next month. Iglesias said during a concert in Budapest in March that he's loving his new role as dad.
"I became a father about 12 weeks ago, and I can absolutely tell you two things," the 42-year-old singer said. "Love my babies! I love them so much."
Iglesias posted a new picture Monday of himself holding one of his twins.
"I still can't believe..... you're mine," he gushed in the caption.
Kournikova and Iglesias have been together 16 years. The pair met on the set of Iglesias' "Escape" music video and made their red carpet debut as a couple at the 2002 MTV Video Music Awards.