Wednesday 15 July 2015

How to determine estimated date of delivery(EDD)

Detecting the estimated date of delivery(EDD) is important in the management of pregnancy.

EDD can be calculated according to the last menstrual period. This will be reliable if the woman is having the previous 3 regular menstrual cycles.
 Generally 9 months and 7 days from the last menstrual period can be considered as EDD.
 If woman is having irregular menstrual cycles or if there is any history of usage of birth control like contraceptive pills etc in last three months, the last menstrual period may not help in predicting the estimated date of delivery.
Other methods of evaluating the estimated date of delivery are evaluating the uterine size periodically.
 But sometimes obesity, altered position of the uterus, amount of the liquor etc can influence this method.
 The date of delivery can be calculated according to the first date of hearing the fetal heart tones.

Doppler devices can hear fetal heart tones at around 10 weeks whereas standard obstetrical stethoscope can hear at 20 weeks.
Expected date of delivery can be calculated according to the date of first positive pregnancy test. Adding 4 to 5 weeks to positive pregnancy date can give the approximate date of delivery.
Date of fruitful coitus can also help in finding the EDD. Around 8 months 3 weeks from the date of fruitful coitus or ovulation can approximately estimate the EDD.
 Ultrasound also helps in estimating the expected date of delivery.
 Usually early ultrasound at around 9 to 11 weeks gives accurate EDD. Whereas upto 24 weeks also ultrasound can help in estimating approximate EDD. But usually EDD by ultrasound alone is unreliable after 30 weeks.
Calculating the estimated date of delivery according to two parameters like last menstrual period and early ultrasound is more accurate and reliable compared with any single parameter.
But usually only 4 % of women deliver on expected date of delivery, whereas around 80% percent of women deliver during the period of 2 weeks before and one week after the expected date of delivery.

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