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How To Determine First Day Of Menstruation Cycle?

Posted on Sat, 8 Nov 2014

Question: If you are due for a period the 6th of February and take norethisterone a few days before to delay your period. You then stop taking if after a few days and have a normal period again on the 12th till around about the 17th of February, does the 1st day of your cycle start from the bleed that you had the week later or remain on when you were meant to come on? Does it affect fertility dates?

Answered by Dr. Dr. Soumen Patra (31 minutes later)

Brief Answer:
12th February will be D1 of cycle.

Detailed Answer:
Hello,

Thanks for writing to us.

If you got your period on 12th February after taking Norethisterone pill, then it will be the D1 of your new menstrual cycle.

In that case, your ovulation or fertility date will be SHIFTED from original date and it would be around 26th to 28th February in case of 28-30 days regular cycle.

Hope, it helps for your information. Kindly, close the discussion if you don't have any other query.

Wish your good health and take care yourself.

Regards,
Dr S Patra

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Above answer was peer-reviewed by : Dr. Yogesh D

Follow up: Dr. Dr. Soumen Patra (18 minutes later)

Thank you it does help. Basically my boyfriend had sex with a girl before he met me on the 2nd of February 2014, she also slept with another guy on the 26th of February 2014. Her due date is November 13th based on scans. She had a period January 9th and took the norethisterone a few days before her next due period on the 6th, to delay it as she wanted to to out drinking that weekend. She then had a period after this from the 12th till the 17th of February. What I don't understand is that the dating scan puts her LMP on the 6th, when she was meant to be due but she bled a week later. Her ovulation dates would have been February 20th so neither guy is in the equation..... What are the possibilities my boyfriend is the father if she last slept with him on the 2nd of February and used protection?

Answered by Dr. Dr. Soumen Patra (33 minutes later)

Brief Answer:
Your boyfriend is NOT the father.

Detailed Answer:
Hello,

Thanks for follow up query.

Ultrasound scan gives a gross information regarding fetal maturity and dating at the time of scanning. It DOESN'T always correspond with Last Menstrual Period date (LMP). There may be 7 to 10 days difference in between original Period date and ultrasound determined period date.

There is NO chance of being father of your boyfriend if he did sexual intercourse on 2nd February as it was SAFE day (non-fertile day). Don't be worried.

Hope, I have answered your queries. Kindly, close the discussion.

All the best and good luck.

Regards,
Dr S Patra

Note: Revert back with your gynae reports to get a clear medical analysis by our expert Gynecologic Oncologist. Click here.

Above answer was peer-reviewed by : Dr. Yogesh D