Erroneous calculation of the expected date of delivery by medical professionals

Background: Naegele's rule, which is used to estimate the expected date of delivery (EDD), presumes that the subject is menstruating regularly every 28 days. For subjects with lengthier or shorter cycles, correction is needed while calculating the EDD. A majority of medical professionals are unaware of this and succumb to errors. The author has published Parikh's formula as an alternative that does not require any additional correction. This study was aimed at evaluating awareness among medical professionals regarding the importance of menstrual history and utility of Parikh's formula in minimizing errors. Materials and Methods: One twenty-six medical students and interns from four medical colleges in India and 24 medical officers from a primary health center were enrolled for the study. A questionnaire with a history of a woman with a regular cycle of 35 days was distributed to each participant and they were asked to calculate the EDD. Participants were then educated on Parikh's formula and asked to calculate the EDD again by using that formula. Results: Only 10 (6.66%) of 150 participants calculated the EDD correctly by using their conventional methods. After explaining Parikh's formula, this proportion raised to 99%, i.e., 147 of 150 participants, the difference being statistically significant at P Conclusion: A majority of students, interns, and medical officers are unaware of the importance of previous menstrual history while calculating the EDD. If Parikh's formula is used, errors in calculating the EDD can be reduced significantly.