DUE DATE, invisible readers!
Jane is zero today! Have I explained the term "adjusted age"? Pretty simple really. You just subtract the number of weeks Jane was premature from her chronological age. Today Jane is 13 weeks old, and she was 13 weeks premature, so today is her zero day. Before that she was however many gestational weeks she would have been; yesterday she was 39 weeks 6 days. Get it?