Determining Paternity: Who is the Father Based on Pregnancy Dates?

Pregnancy date

Hello, I had intercourse with man A on June 26, and my period started on June 30.
I also had intercourse with man B from July 10 to July 17, and my period came again on July 27.
On August 12, a pregnancy test showed negative, but on August 26, it showed two lines.
On September 5, the doctor told me I was 4 weeks pregnant, and my due date is May 11 of next year.
Is the child from man A or man B?

Eva, 20~29 year old female. Ask Date: 2023/11/24

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello, based on your description, it is difficult to make a determination.
I recommend consulting with the examining physician, and if necessary, a paternity test should be conducted.
Thank you! Wishing you peace and health.
Dr.
Zhang

Reply Date: 2023/11/24

More Info

Determining paternity based on pregnancy dates can be quite complex, especially when there are multiple potential fathers involved and the timing of sexual encounters is close together. In your case, you have provided specific dates of sexual activity with two different partners, A and B, along with the dates of your menstrual cycles and pregnancy tests.
To analyze your situation, let’s break down the timeline:
1. Menstrual Cycle: You mentioned that your menstrual cycle is regular, with your last period starting on June 30. This is crucial because ovulation typically occurs about 14 days before the start of your next period. If we assume a standard cycle length of around 28 days, ovulation would likely have occurred around July 14.

2. Sexual Encounters:
- You had sexual intercourse with A on June 26, which is before your last menstrual period began.

- You then had sexual intercourse with B between July 10 and July 17.
3. Pregnancy Test Results: You took a pregnancy test on August 12, which was negative, and then another on August 26, which was positive. You were informed by your doctor on September 5 that you were approximately 4 weeks pregnant, which would place the estimated conception date around August 12.

4. Estimated Due Date: Your estimated due date (EDD) is May 11 of the following year, which aligns with a typical 40-week gestation period from the estimated conception date.

Given this timeline, it is important to note the following:
- The sexual encounter with A occurred before your last menstrual period, which means it is unlikely to have resulted in pregnancy, as sperm can survive in the female reproductive tract for up to five days, but the timing does not align with ovulation.

- The sexual encounters with B occurred after your last menstrual period and closer to the time of ovulation, making it more likely that B is the father of the child.

However, it is essential to understand that while these calculations can provide a reasonable assumption, they are not definitive. The only way to confirm paternity with certainty is through genetic testing (DNA testing).
In summary, based on the information provided, it appears more likely that B is the father of your child due to the timing of your sexual encounters in relation to your ovulation period. However, for absolute certainty, a paternity test would be necessary. It is also advisable to consult with a healthcare provider for further guidance and support during this time, as navigating relationships and pregnancy can be emotionally challenging.

Similar Q&A

Determining Paternity: Who is the Father of My Child?

Hello Doctor: I got my period on February 16 and had unprotected intercourse with Male A from February 16 to February 19. Starting from February 23, I had regular sexual intercourse with Male B, which included both withdrawal and ejaculation inside. On April 1, I took a pregnancy...

Dr. Huang Yuande reply Obstetrics and Gynecology
If the ultrasound shows a gestational age of 5 weeks, the conception date would be approximately 3 weeks prior, which would place it around March, assuming that the menstrual cycle is regular enough to make this determination.

Who is the Likely Father? Understanding Pregnancy Timing and Conception

Based on the menstrual cycle from April 1 to April 7, with light bleeding on April 6 and 7, and considering unprotected intercourse with Male A on April 6, 7, and 9, followed by unprotected intercourse with Male B on April 23, 24, and 26, and a pregnancy test on May 30 indicating...

Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, it is more likely to be B. Wishing you good health.

Determining Paternity: Who's the Father When Dates Are Uncertain?

Irregular menstruation. On February 7, I had protected intercourse with a male friend. After that, I continued to have sexual relations with my ex-boyfriend, but the timing was uncertain (sometimes without protection). On July 10, I confirmed that I am 10 weeks pregnant. Is it po...

Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, it seems that there might be a greater chance with your ex-boyfriend. Wishing you good health.

Determining Paternity: Who is More Likely to Be the Father?

Hello, Director Zhang. I would like to ask about the results of my pregnancy test. On September 19, I received a result with one dark line and one faint line. During my first prenatal check-up on October 17, the doctor mentioned that I was exactly 9 weeks pregnant. Can the gestat...

Dr. Zhang Kunmin reply Obstetrics and Gynecology
Hello, the questioner: If someone has irregular menstrual cycles, using ultrasound estimation methods may lead to significant inaccuracies. It is recommended to use DNA testing for more accurate results if needed. Thank you! Wishing you peace and health, Dr. Zhang.