Conception Dates: A Guide for Women - Obstetrics and Gynecology

Days before pregnancy

I would like to ask about my menstrual cycle.
My period started on September 10 and ended on September 14.
The next month, my period started on October 14 and ended on October 18.
However, on October 16, I had intercourse during my period, and ejaculation occurred inside.
On October 27, I had intercourse without a condom, but there was no ejaculation.
If I were to become pregnant, which date would it likely be? (I would like a more accurate answer, but I understand that it also depends on how many weeks pregnant I am for confirmation.)

Tina, 20~29 year old female. Ask Date: 2019/11/16

Dr. Huang Jianzhong reply Obstetrics and Gynecology

Menstruation ended on September 14, and the next period was from October 14 to 18.
However, intercourse occurred on October 16 during the menstrual period with ejaculation.
On October 27, intercourse happened without a condom (but without ejaculation).
If pregnancy occurred, which day would it be? (I want a more accurate answer, but it still depends on how many weeks pregnant one is.) Answer: It depends on how many weeks pregnant one is.

Reply Date: 2019/11/16

More Info

Understanding conception dates and the menstrual cycle is crucial for women who are trying to conceive or avoid pregnancy. The menstrual cycle typically lasts about 28 days, but it can vary from woman to woman, ranging from 21 to 35 days. The cycle is divided into several phases: the menstrual phase, the follicular phase, ovulation, and the luteal phase.

In your case, your menstrual cycle started on September 10 and ended on September 14, with your next period beginning on October 14 and ending on October 18. Based on a typical 28-day cycle, ovulation usually occurs about 14 days before the start of your next period. Therefore, if your next period started on October 14, you would likely ovulate around October 1.
Now, regarding the sexual activity you mentioned: having intercourse during your period (October 16) is generally considered low-risk for conception, as ovulation has not yet occurred. However, sperm can survive in the female reproductive tract for up to five days, so if you had unprotected sex close to ovulation, there is a slight chance of conception.
On October 27, you mentioned having intercourse without a condom but did not ejaculate. The risk of pregnancy from this encounter is significantly lower than if ejaculation had occurred, but it is not zero. Pre-ejaculate fluid can contain sperm, and if any sperm were present, there is a possibility of conception.

To determine if you are pregnant, the most reliable method is to wait until after your next expected period and take a home pregnancy test. Pregnancy tests are most accurate when taken after a missed period, as they measure the hormone hCG (human chorionic gonadotropin), which is produced after a fertilized egg implants in the uterus.

If you are trying to conceive, tracking your ovulation can help increase your chances. You can do this through various methods, such as monitoring basal body temperature, observing changes in cervical mucus, or using ovulation predictor kits.
If you are concerned about the possibility of pregnancy or have irregular cycles, it may be beneficial to consult with a healthcare provider. They can offer personalized advice and help you understand your cycle better. Additionally, if you experience any unusual symptoms or changes in your menstrual cycle, it is essential to seek medical advice.

In summary, while the timing of your sexual encounters suggests a lower risk of pregnancy, it is always best to use protection if you want to avoid unintended pregnancy. If you suspect you might be pregnant, wait until after your next period to take a test for the most accurate results.

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