The Women's Hospital of Texas announced the birth of Ace, Blaine, Cash and Dylan Montalvo on Monday, ABC News reported. The boys, two sets of identical twins, arrived on Valentine's Day.
"We didn't expect it, we were trying for just one and we were blessed with four," Montalvo said.
She said the babies were conceived without assisted reproduction, which increases the chance of multiple births.
"No fertility drugs were used. We planned the pregnancy -- I guess we just succeeded a little too much!" Montalvo said.
Dr. James Grifo of the New York University Fertility Center said the chance of two sets of identical twins in one pregnancy is about one in 10,000 when couples use in vitro fertilization and much rarer without it.
Manuel Montalvo Jr., the babies' father, said he and his wife still hope to give the boys a little sister.
"We want a girl," he told ABC.