P and Lee (D) met in New York early in 2000. P resided in Belgium but made several trips to visit D. A romantic relationship developed between them. In August 2000, P moved into D's New York apartment. While continuing to live in Belgium, P spent about a quarter of his time in New York. In September 2000, D learned that she was pregnant with P's child. D began prenatal care in New York, but because P refused to pay the cost of delivery of the baby in the United States and Belgium offered free medical services, D agreed to have the baby in Belgium. She traveled to Belgium on a three-month tourist visa, bringing along only one or two suitcases. D left the rest of her belongings, including her non-maternity clothes, in the New York apartment. D lived out of her suitcases. When her visa expired, she did not extend it. The baby was born on May 14, 2001. The relationship between the parties had deteriorated. After initially resisting, P signed the consent form that enabled D to get an American passport for Baby S and agreed to D's return to the United States with Baby S in July 2001. P made several trips to the United States, and the parties made several attempts to reconcile. P then filed this petition. Following an evidentiary hearing, the district court denied the petition. The district court held that D had failed to meet his burden of proving that Baby S was a habitual resident of Belgium. It reasoned that a two-month-old infant, who is still nursing, has not been present long enough to have an acclimatization apart from his parents. This appeal followed.