Can a baby be born in seven and half months of pregnancy??

Patient: Hi All,I just need a clarification, My girl got her periods stopped within 15 days from the day having intercourse for the fisrt time (As we had intercourse in the middle of the month and she gets he periods in the beginning of every month)and the period which she had 10-12 days before the first intercourse was also stopped in first day itself (As she said), Laterfound that she got pregnant and then she gave birth to a baby in exactly Seven and half months from the date of first intercourse(Doctor actually fixed a DOD 15 days later than the exact date from when she delivered), that too baby is hale and healthy (Its a girl baby).Please advice whether is this possible by any means.If neede more information lemme know, but help me get cleared regarding this please am confused…Thanks in advance 🙂