Formula to determine dating age range
The perception of fetal movement by the patient, often referred to as quickening, is a relatively late sign of pregnancy, usually occurring at 19-21 weeks' gestation in nulliparous women and 17-19 weeks' in multiparous women.Before the advent of pregnancy tests and ultrasonography, quickening was often the method by which a suspected pregnancy was confirmed; however, at present, it has little diagnostic value.Knowing the date of the first positive pregnancy test result allows the calculation of a minimum GA. For example, if the test was performed 4 weeks ago and the test is known to return positive results as early as 1 week after conception, then the minimum conceptional age (CA) would be 5 weeks (GA, 5 2 = 7 wk of amenorrhea).This information can be useful in clinical practice if the test finding has been documented by a health care professional.The accuracy of menstrual history in women with a history of oligo-ovulation, such as those with polycystic ovarian syndrome, should be questioned.If conception occurred while oral contraceptives or long-acting progestogens were being taken, the LMP cannot be used because it has no relation to the time of ovulation.Therefore, giving a range for the likely date of birth (eg, EDD -2 weeks to EDD 1 week) is more useful.
The size of the uterus can be assessed by pelvic examination or by abdominal palpation.
In rare cases, the date of coitus is known, and this may be useful in calculating the length of pregnancy.
Formula to determine dating age range comments