Determining Paternity and Pregnancy Timeline: Key Questions Answered

Calculating the Estimated Due Date (EDD)

Hello Doctor, I would like to ask a few questions.
My menstrual cycle is about 31-32 days, and my last period was on December 27.
I expect to ovulate around January 13-14, so I had unprotected intercourse with Male A from January 12-14 (I experienced ovulation pain on January 13 for several days).
However, on January 18, I had protected intercourse with Male B after drinking.
I took a pregnancy test on February 3, which showed two lines.
On February 6, a vaginal ultrasound did not show a gestational sac, and my HCG level was just over 900.
On February 10, I visited an obstetrician-gynecologist, and the ultrasound showed a gestational sac measuring only 0.5 cm, indicating that I am just over four weeks along.
I would like to ask the doctor: 1.
Is the child from Male A or Male B? 2.
Given that the gestational size is only four weeks, it should correspond to conception around January 27, when there was no sexual intercourse, so how is this possible? 3.
Is this pregnancy viable?

huzi, 30~39 year old female. Ask Date: 2022/02/15

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, based on the size observed in the ultrasound, it is possible that it is a male fetus.
However, since you have been using contraception, it is difficult to say for certain.
As for whether everything is normal, it will require monitoring.
Wishing you good health.

Reply Date: 2022/02/15

More Info

Determining paternity during pregnancy can be a complex issue, especially when multiple sexual encounters occur close together in time. Based on the timeline you provided, let's break down the key points to address your questions.

1. Paternity Determination: Given that you had unprotected intercourse with A on January 12-14, which coincides with your ovulation period, and then had protected intercourse with B on January 18, the likelihood of A being the father is higher. However, since sperm can live in the female reproductive tract for up to five days, it is still possible for B to be the father if ovulation occurred later than expected. The best way to confirm paternity would be through a DNA test after the baby is born, as prenatal paternity testing can carry risks.

2. Embryonic Development Timeline: You mentioned that the ultrasound on February 10 showed an embryo measuring only 0.5 cm, which corresponds to about four weeks of gestation. This suggests that conception likely occurred around January 27. If you did not have any sexual intercourse around that time, it raises questions about the timing of ovulation and fertilization. It's important to note that ovulation can sometimes be unpredictable, and factors such as stress, illness, or hormonal fluctuations can affect your cycle. Additionally, the HCG levels you mentioned (900+) indicate that you are indeed pregnant, but the timing of conception may not align perfectly with your expected ovulation date.

3. Pregnancy Viability: At four weeks, it is still early in the pregnancy, and many factors can influence whether the pregnancy will continue successfully. Early ultrasounds are crucial for assessing the viability of the pregnancy, and the presence of a gestational sac is a positive sign. However, it is essential to follow up with your healthcare provider for further monitoring. They may recommend additional ultrasounds to track the development of the embryo and check for a heartbeat, which typically becomes detectable around six weeks of gestation.

In summary, while the timeline suggests a higher probability of A being the father, the only definitive way to confirm paternity is through DNA testing after birth. The timing of conception may not align with your expectations, and it's crucial to maintain regular check-ups with your healthcare provider to monitor the health of your pregnancy. If you have any concerns about the viability of the pregnancy or your health, do not hesitate to reach out to your doctor for personalized advice and support.

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