Question
Dear doctor, Can you advise me on how to accurately calculate the gestational age of a fetus based on the date of coitus or by what method gives the least error in the result? Thank you.
-Anonymous Question
Answer
Dear Sir/Madam, Calculating gestational age based on the date of coitus is a method, which has much lower accuracy compared to ultrasound and gestational age calculation is only absolutely accurate in the case of IVF due to the known date of embryo transfer.
In standard obstetric practice, gestational age is determined based on the first day of the last menstrual period (2 weeks before ovulation). For example, if today is August 14, 2020, and the woman's last menstrual period was July 3, 2020, then the current gestational age will be 6 weeks and the likely date of ovulation will be July 17, 2020.
If you know the exact date of sexual intercourse and only had intercourse once within 3-4 weeks, the gestational age will be calculated by adding 2 weeks from the date of coitus. However, as the doctor mentioned above, the accuracy of this method is not high.
Thank you for your trust and for sharing your questions about the accurate calculation of gestational age with Vinmec Health System. Wishing you good health.
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Answered by Specialist Doctor II Nguyen Thu Hoai - Unit Head of Obstetrics and Gynecology Clinic - Obstetrics Department - Vinmec Times City International Hospital
