Calculating Conception Date: Your Pregnancy Timeline

To estimate the conception date?

Hello, doctor.
My menstrual period was from July 15 to July 21, and then from August 14 to August 20.
I had unprotected intercourse with my ex-boyfriend on August 21, during which he withdrew before ejaculation (there was still a little bit of brown discharge that day...).
I then had unprotected intercourse with my current boyfriend on August 26, and he ejaculated inside me, followed by another instance on September 3, where he also ejaculated inside me.
On September 10, I noticed some pink spotting (it disappeared after wiping).
I am currently pregnant, and during an ultrasound on September 29, the measurement indicated a gestational age of 5 weeks and 6 days, with the gestational sac measuring 1.55 cm.
I would like to know the estimated date of conception.
Is the child my current boyfriend's? What could the pink spotting on September 10 indicate? Thank you!

penny, 20~29 year old female. Ask Date: 2017/10/04

Dr. Huang Jianzhong reply Obstetrics and Gynecology

Your menstrual period ended on July 21, and then again on August 20.
You had unprotected intercourse with your ex-boyfriend on August 21, with ejaculation outside, and there was a small amount of brown discharge that day.
You then had unprotected intercourse with your current boyfriend on August 26 and again on September 3, both with ejaculation inside.
On September 10, you noticed a small amount of pink spotting that disappeared after wiping.
Currently, you are pregnant, and on September 29, an ultrasound showed a gestational sac measuring 1.55 cm, indicating approximately 5 weeks and 6 days of gestation.

To estimate the conception date, it is likely around the time of your unprotected intercourse with your current boyfriend, given the timing of your menstrual cycle and the ultrasound findings.
The likelihood that the child is your current boyfriend's is higher.
The pink spotting on September 10 could be related to implantation bleeding, which can occur when the fertilized egg attaches to the uterine lining.

Reply Date: 2017/10/04

More Info

To determine the conception date and clarify your pregnancy timeline, we need to analyze the information you provided regarding your menstrual cycle and sexual activity.
Based on your menstrual history, you had your last period from July 15 to July 21, and your next period from August 14 to August 20. This suggests that your average cycle length is approximately 28 to 30 days. Ovulation typically occurs about 14 days after the first day of your last menstrual period (LMP), which would place your ovulation around August 28 to August 30, given your cycle length.

You mentioned having unprotected intercourse on August 21 with your ex-boyfriend and then again on August 26 and September 3 with your current boyfriend. Since sperm can live inside the female reproductive tract for up to five days, it is possible that intercourse on August 26 or September 3 could have led to conception if ovulation occurred shortly after those dates.

Your ultrasound on September 29 indicated that the embryo was measuring 5 weeks and 6 days, which aligns with a conception date around August 30. This suggests that the most likely date of conception is close to your ovulation date, which would be after your encounter with your ex-boyfriend and likely after your sexual activity with your current boyfriend.

Regarding the pink spotting you experienced on September 10, this could be implantation bleeding, which occurs when the fertilized egg attaches to the uterine lining. This typically happens about 6 to 12 days after conception, which fits the timeline if conception occurred around August 30.

In summary, based on the provided information, it is likely that the conception occurred after your sexual encounter with your ex-boyfriend, making your current boyfriend the probable father of the child. However, it is essential to note that determining paternity definitively would require a paternity test after the baby is born.

If you have any concerns about your pregnancy or the health of your baby, it is crucial to consult with a healthcare provider. Regular prenatal check-ups are vital for monitoring the health of both you and your baby throughout the pregnancy. Additionally, if you experience any unusual symptoms or have questions about your pregnancy, do not hesitate to reach out to your healthcare provider for guidance and support.

Similar Q&A

Calculating Conception Date Based on Due Date: A Guide

If the due date is September 20, the estimated conception date would be around December 27 of the previous year. Currently, you are at 19 weeks of gestation.

Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, it should be around the end of December. Wishing you good health.

How to Calculate Your Conception Date from Last Menstrual Period?

If you know the date of your last menstrual period (LMP) and your due date, you can estimate the date of conception. Typically, conception occurs about two weeks after the first day of your last menstrual period. If you only know your due date and are unsure of your last menstr...

Dr. Lin Wenbin reply Obstetrics and Gynecology
If the menstrual cycle is not calibrated by a physician, it cannot be accurately determined. If the due date is calculated by a physician, then the ovulation date can be accurately estimated. Self-calculations may not be precise.

Calculating Conception Date Based on Due Date: May 14th Insights

Hello, if the due date is May 14 of this year, the estimated conception date would be around August 21 of the previous year.

Dr. Huang Yiwen reply Obstetrics and Gynecology
Hello, Miss Xiao Xiao: If your menstrual cycle is regular and occurs once a month, then your estimated ovulation date would be around two to three days before or after August 21 of last year.

Calculating Conception Date Based on Due Date: A Guide for Expecting Mothers

If the due date is October 23, the estimated conception date would be around January 16. Since you took a pregnancy test on February 6 and only saw one line, it could indicate a negative result. However, when you tested again on February 14 and the second line appeared slowly wit...

Dr. Zhang Kunmin reply Obstetrics and Gynecology
Hello, the date of conception is usually estimated accurately through ultrasound at around 8 to 9 weeks of pregnancy. Based on your description, it is difficult to make an accurate calculation and explanation. Thank you! Wishing you peace and health, Dr. Zhang.