Se realizan 2 calendarios obstétricos para hallar la edad gestacional a partir del mes de inicio de la última menstruación hasta la fecha deseada o de consulta, basados en los días que posee cada mes, y de la misma forma se creó una regla sencilla y precisa para hallar la fecha probable de parto según la FIGO; nos percatamos de la exactitud y rapidez de cada cálculo y el bajo costo para su aplicación masiva, por su gran utilidad.
2 obstetric calendars were made to find the gestational age starting from the month when the last menstruation began to the wished date or the date of the appointment, based on the number of days every month has. A simple and precise rule was also created to know the probable date of delivery according to the International Federation of Gynecoobstetrics. The accuracy and rapidity of every calculation, as well as the low cost for their mass application and their great usefulness were considered.