Date of conception
Doctor: My due date is June 5th.
During an ultrasound examination on November 20th, I was 11 weeks and 6 days pregnant.
The first day of my last menstrual period was August 20th.
I had unprotected intercourse on September 3rd, 4th, and 5th, and another instance on September 7th with withdrawal method.
Can you tell me what the conception date would be?
Xiao Yu, 30~39 year old female. Ask Date: 2021/11/22
Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, your due date is June 5th, which means conception likely occurred around September 12th.
Wishing you good health!
Reply Date: 2021/11/22
More Info
To determine the conception date based on your ultrasound findings and menstrual cycle, we can analyze the information provided. Your estimated due date (EDD) is June 5th, which is a crucial piece of information. Typically, the due date is calculated as 40 weeks (280 days) from the first day of your last menstrual period (LMP). In your case, the LMP is August 20th.
Using the standard calculation method, if we count 40 weeks from August 20th, we arrive at a due date of May 26th. However, your ultrasound indicates that you were 11 weeks and 6 days pregnant as of November 20th. This suggests that the conception likely occurred around 11 weeks prior to that date.
Calculating backward from November 20th, 11 weeks and 6 days would place the conception date around September 10th. This aligns with your menstrual cycle, as ovulation typically occurs about 14 days after the first day of your last period. Given that your LMP was August 20th, ovulation would likely have occurred around September 3rd to September 5th, which corresponds with the dates you mentioned for sexual intercourse.
The sexual encounters you described on September 3rd, 4th, and 5th are all within the fertile window, making it plausible that conception could have occurred from any of those encounters. The encounter on September 7th, while involving external ejaculation, is less likely to have resulted in conception, as it falls outside the typical ovulation window.
In summary, based on your due date, ultrasound findings, and menstrual cycle, the most likely conception date is around September 10th, with the sexual encounters on September 3rd to 5th being the most relevant.
It’s important to note that while these calculations provide a good estimate, individual variations in menstrual cycles and ovulation can affect the exact timing of conception. If you have further questions or concerns about your pregnancy, it is advisable to consult with your healthcare provider for personalized guidance and support.
Similar Q&A
Understanding Conception Dates Based on Ultrasound and Menstrual Cycle
Hello doctor, I would like to ask about the ultrasound examination. The first day of the last menstrual period was on January 15, and the estimated due date is October 22. The ultrasound on March 13 showed 8 weeks and 1 day with a crown-rump length (CRL) of 1.69 cm. The ultrasoun...
Dr. Zhang Kunmin reply Obstetrics and Gynecology
Hello, the error in calculating the gestational age based on the weeks of pregnancy can be significant. For individuals who engage in frequent sexual activity, it is not advisable to use this method for calculation, as it often leads to unnecessary disputes. Thank you! Wishing yo...[Read More] Understanding Conception Dates Based on Ultrasound and Menstrual Cycle
Understanding Pregnancy Weeks: Calculating Conception Date vs. Last Menstrual Period
To determine the estimated date of conception based on your menstrual cycle and ultrasound findings, we typically consider the first day of your last menstrual period (LMP) as the starting point for calculating gestational age. Your last menstrual period began on February 10, a...
Dr. Huang Yuande reply Obstetrics and Gynecology
Due to the administration of emergency contraceptive pills, the assessment can only be made through ultrasound. Based on this estimation, conception likely occurred around March 21.[Read More] Understanding Pregnancy Weeks: Calculating Conception Date vs. Last Menstrual Period
Estimating Conception Date Based on Due Date: A Guide for Expecting Mothers
Hello Dr. Huang, I would like to inquire about the conception date. An ultrasound on August 12 showed a baby with a gestational age of 16 weeks and 4 days, with an estimated due date of January 27 next year. My menstrual cycle is somewhat irregular, but averages around 35 days. I...
Dr. Huang Jianzhong reply Obstetrics and Gynecology
On August 12, an ultrasound examination revealed a baby at 16 weeks and 4 days gestation, with an estimated due date of January 27 of the following year. The menstrual cycle is somewhat irregular, averaging 35 days. Menstruation occurred from February 18 to February 22, but there...[Read More] Estimating Conception Date Based on Due Date: A Guide for Expecting Mothers
How to Determine Your Conception Date Based on Ultrasound Results
An ultrasound examination of the fetus at 29 days suggests that conception likely occurred approximately 29 days prior to the ultrasound. However, considering the typical menstrual cycle, ovulation usually occurs about 14 days before the start of the last menstrual period. Theref...
Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, I conceived approximately three weeks ago. Wishing you good health.[Read More] How to Determine Your Conception Date Based on Ultrasound Results
Related FAQ
(Obstetrics and Gynecology)
Conception(Obstetrics and Gynecology)
Due Date(Obstetrics and Gynecology)
Anovulatory Menstruation(Obstetrics and Gynecology)
Ovulation Period(Obstetrics and Gynecology)
First Menstruation(Obstetrics and Gynecology)
Delayed Menstruation(Obstetrics and Gynecology)
Ultrasound(Obstetrics and Gynecology)
Premenstrual Syndrome(Obstetrics and Gynecology)
Menstrual Regulation(Obstetrics and Gynecology)