
How Can Date Of Conception Be Calculated Based On Due Date?

Question: if your due date is july 5 2015 what are your most accurate dates of conception?
I got this thats saying she found out she was pregnant in december but she her last pms,on oct 1st and,missed it,nov 1st and she's due on july 5th 2015 i'm thinking she got in late september or early october 2014
I got this thats saying she found out she was pregnant in december but she her last pms,on oct 1st and,missed it,nov 1st and she's due on july 5th 2015 i'm thinking she got in late september or early october 2014
Brief Answer:
Around mid september 2014
Detailed Answer:
Hi XXXX, I have gone through your question. According to the due date of 5 th July 2015, the last menstrual period should be around 28 th September, 2014.
The ovulation and hence the conception occurs around 14 days prior to the last menstrual period, and hence in the above situation, the conception would have occurred around 14 th September, 2014.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Around mid september 2014
Detailed Answer:
Hi XXXX, I have gone through your question. According to the due date of 5 th July 2015, the last menstrual period should be around 28 th September, 2014.
The ovulation and hence the conception occurs around 14 days prior to the last menstrual period, and hence in the above situation, the conception would have occurred around 14 th September, 2014.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Above answer was peer-reviewed by :
Dr. Neel Kudchadkar


she's trying to say she conceived around late october around the 18-25 2014. I think that's impossible because of her due date being july 5 2015 it doesn't add up to me. but i'm not a doctor so I don't know.
Brief Answer:
Conception has occured in September 2014
Detailed Answer:
Hi XXXX, thanks for responding. As I have mentioned earlier, if her due dates were calculated by her last menstrual period, then the date of conception would be around 14th September, 2014.
If her due date was calculated even by first trimester ultrasound, then the date of conception can be 7 days before or after 14th September, 2014 (the duration during which she might have conceived can be from 7th September to 21st September, 2014) as first trimester ultrasound can have a calculation error of 7 days.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Conception has occured in September 2014
Detailed Answer:
Hi XXXX, thanks for responding. As I have mentioned earlier, if her due dates were calculated by her last menstrual period, then the date of conception would be around 14th September, 2014.
If her due date was calculated even by first trimester ultrasound, then the date of conception can be 7 days before or after 14th September, 2014 (the duration during which she might have conceived can be from 7th September to 21st September, 2014) as first trimester ultrasound can have a calculation error of 7 days.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Above answer was peer-reviewed by :
Dr. Pradeep Vitta


she's only
28 weeks so she couldn't have conceived in september.
28 weeks so she couldn't have conceived in september.
Brief Answer:
Gestation age 28 weeks 1 day by LMP of 28 september 2014
Detailed Answer:
Hi XXXX, thanks for responding. By the last menstrual date of 28 september 2014, her gestation age today is 28 weeks 1 day by calculation.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Gestation age 28 weeks 1 day by LMP of 28 september 2014
Detailed Answer:
Hi XXXX, thanks for responding. By the last menstrual date of 28 september 2014, her gestation age today is 28 weeks 1 day by calculation.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Above answer was peer-reviewed by :
Dr. Pradeep Vitta


so that means she couldn't have gotten pregnant on or after the 18th of oct 2014 because she was already pregnant by then am I correct?
Brief Answer:
you are correct
Detailed Answer:
Hi XXXX, thanks for responding. Yes you are correct in your interpretation. She would be pregnant on 18 th october 2014.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
you are correct
Detailed Answer:
Hi XXXX, thanks for responding. Yes you are correct in your interpretation. She would be pregnant on 18 th october 2014.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Above answer was peer-reviewed by :
Dr. Vinay Bhardwaj


so you're almost 100% sure that she was already pregnant before oct 18 y. I trust your judgement however.
Brief Answer:
Correct if cycles regular and no pills intake
Detailed Answer:
Hi XXXX, thanks for responding. If the due date of 5 July2015 is correct, then the estimated date of conception is around 14 th September2014, provided the following criteria are true:
1. Her previous menstrual cycles were regular( of 26-32 days)
2. There is no intake of oral contraceptive pills for 3 months prior to conception.
If cycles are irregular or of more than 35 days or if there is intake of oral contraceptive pills 3 months before the conception, then the ovulation becomes irregular and delayed, and hence the conception is delayed. In such conditions, the correct gestational age is calculated by the first trimester ultrasound.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Correct if cycles regular and no pills intake
Detailed Answer:
Hi XXXX, thanks for responding. If the due date of 5 July2015 is correct, then the estimated date of conception is around 14 th September2014, provided the following criteria are true:
1. Her previous menstrual cycles were regular( of 26-32 days)
2. There is no intake of oral contraceptive pills for 3 months prior to conception.
If cycles are irregular or of more than 35 days or if there is intake of oral contraceptive pills 3 months before the conception, then the ovulation becomes irregular and delayed, and hence the conception is delayed. In such conditions, the correct gestational age is calculated by the first trimester ultrasound.
Hope you found the answer helpful. Please do get back for further queries.
Wishing you good health.
Regards,
Dr Deepti Verma
Above answer was peer-reviewed by :
Dr. Yogesh D

Answered by

Dr. Deepti Verma
OBGYN, Maternal and Fetal Medicine
Practicing since :2009
Answered : 5064 Questions
Get personalised answers from verified doctor in minutes across 80+ specialties
