Due dates are determined by a number of factors.
Early on in pregnancy, it can be estimated by adding aprox 9 months to the first day of a women's menstrual cycle.
Later, an ultrasound a pinpoint an expected delivery date more accurately by measuring the growth and size of a fetus and comparing it with known normal ranges. This is usually done at the 7 week mark.
From there, medical and genetic factors beyond the control of the patient and doctor can cause labour to be induced earlier or later than the ultrasound date.
Other than regular contractions and breaking of water, there is no way to determine the delivery more accurately than the 4 week Window provided to you.
Congratulations and best of luck
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.