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Dr. Andrew Rynne

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How to determine the date of conception?

Answered by
Dr. Shanti Vennam


Practicing since :1989

Answered : 7313 Questions

Posted on Fri, 18 May 2018 in Pregnancy
Question: I want to know actually when i have conceived i have irregular cycles
My july month period was 4th july and on 29 july i had non penetrive sex with stranger..from 29 july i started taking duphason on 8th august i got spotted in brown colour following periods ib brown colour..nkw my question is

On 8th august it was my period or implantation bleeding..
From 19 august i started to have sex with my hubby
And on 30september i had ultrasound it dated me 7 week 6 days gestational age..
On 31st october ultrasound dated me 12week 3 days
Now my question is when did i get pregnant ..can 29 july incident had made me pregnant?

If 8th august was my lmp the y does ultrasound dated me 6th august, have i conceived befire?
My due date as lmp is 15 may
And by ultrasound is 12 may

Please help me to find when conception whould have occured

And my mise important question is can ultrasound be wrong?
Answered by Dr. Shanti Vennam 28 minutes later
Brief Answer:
Conception is most likely to have occurred in August.

Detailed Answer:

Thanks for posting your query.

I have gone through your query and would like to offer some suggestions.
1. It is difficult to predict the exact time of ovulation if your menstrual cycles are very irregular. However, if your cycle length varies within a span of ten days, ovulation can be estimated roughly.

2. Non-penetrative intercourse can lead to pregnancy only if it happens to be the fertile period and when pre-ejaculate/ejaculate is deposited on the vagina.

3. Since you experienced withdrawal spotting after using hormone in August, this is likely to be the menstrual period. However, brown color suggests old blood. If you conceived on the 29th of July, this sort of bleeding would mean an unhealthy pregnancy. However, this is not the case and so it is likely that you did not conceive

4. The gestation age estimated at the end of the first trimester is not very erratic; moreover your repeated sonographic views correlate.There is a variation of +or - 1 week when compared to the last menstrual period.

Going by all these facts, it is likely that you have conceived in August.

Hope I have answered your query. Please feel free to contact for further clarifications. I will be happy to help.

Above answer was peer-reviewed by : Dr. Kampana

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