Results: There were a total of 4544 infants participating in the study, of which 2389 (52.6%) were male and the remaining 2155 (47.4%) were female.
Kết quả: trong tổng số 4544 trẻ tham gia nghiên cứu có 2389 (52,6%) trẻ là nam còn lại 2155 (47,4%) trẻ là nữ.