Conception Timing: A Case Study in Fertility

Inquire about the time of conception?

Hello, I had unprotected sexual intercourse with Male A at the end of January and the beginning of February.
Then, I had unprotected sexual intercourse with Male B on March 4th.
My menstrual cycle has typically been regular, occurring every 26-30 days, but I stopped tracking my menstrual dates since the end of last year.
In early March, I experienced some light bleeding, which I initially thought was the onset of my period.
Subsequently, I had mild abdominal pain and noticeable breast tenderness, but my period did not arrive.
On March 18th, I took a pregnancy test, which showed two lines, and on March 22nd, an ultrasound indicated that I was 7 weeks and 4 days pregnant (CRL 13.8 mm) with a heartbeat detected.
On April 8th, another ultrasound showed I was 10 weeks and 2 days pregnant (CRL 38.0 mm).

I would like to know if the conception date is likely to be around the time I had sexual intercourse with Male A at the end of January or the beginning of February.
Is it possible that I conceived after the sexual encounter with Male B on March 4th? Thank you.

Una, 20~29 year old female. Ask Date: 2022/08/17

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, it is difficult to make an accurate judgment; it is more likely to be from the early February incident.
Wishing you good health.

Reply Date: 2022/08/17

More Info

Understanding conception timing is crucial for women trying to conceive or those who are uncertain about their reproductive health. In your case, the timeline of events and the nature of your menstrual cycle provide important clues to determine the likely conception date.

Firstly, it is essential to understand the typical menstrual cycle and ovulation. A regular menstrual cycle usually lasts between 26 to 30 days, with ovulation occurring approximately 14 days before the next expected period. If your cycles have been consistent, ovulation would likely occur around the midpoint of your cycle. Given that you had unprotected intercourse with A in late January to early February, it is plausible that ovulation could have occurred around that time, leading to potential conception.

The bleeding you experienced in early March could be attributed to several factors. It is not uncommon for women to experience light spotting or bleeding around the time of implantation, which occurs when a fertilized egg attaches to the uterine lining. This typically happens about 6 to 12 days after conception. If you had unprotected intercourse with A in late January, and conception occurred shortly thereafter, the timing of your bleeding could align with implantation bleeding.

The subsequent symptoms you described, such as mild abdominal pain and breast tenderness, are also common early signs of pregnancy. These symptoms can occur due to hormonal changes following conception and implantation.

When you had unprotected intercourse with B on March 4, it is less likely that this encounter resulted in conception, especially considering that you had already experienced signs of pregnancy by that time. The positive pregnancy test on March 18 and the ultrasound confirming a gestational age of 7 weeks and 4 days on March 22 suggest that conception likely occurred before your encounter with B.

To summarize, based on your menstrual cycle and the timeline of events, it is highly probable that the conception occurred during the period of unprotected intercourse with A in late January to early February. The encounter with B on March 4 is unlikely to have resulted in conception, given that you were already pregnant by that time.

In conclusion, understanding the timing of ovulation and the signs of early pregnancy can help clarify conception dates. If you have further concerns about your reproductive health or future pregnancies, consulting with a healthcare provider or a fertility specialist can provide personalized guidance and support.

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