Wrong Due Date

Rey

Well my sweet child arrived July 8th, 4 weeks early according to due date. But she was larger than my first born, had long fingernails and eyelashes, got 10s on her apgar, and no issues that are common with preemies like low blood sugar. The pediatrician says they got the due date wrong and she was born at least 38 weeks if not the full 40. Has anyone heard of a due date being that off? I guess I thought since it was determined by sonogram that would be fairly accurate. Haha, it doesn't matter because I habe my beautiful miracle and she's healthy but just wondering if anyone had heard of similar cases.