Pregnancy Testing: When Did I Conceive? - Obstetrics and Gynecology

Pregnancy test negative after 16 days?

Hello, my last menstrual period started on February 3.
I had sexual intercourse on February 28, March 2, and March 9, which was every other week.
My period in March was delayed by two weeks, but on March 18, the pregnancy test showed only one line.
On April 9, the test showed two lines, and the doctor said I was about 4-5 weeks pregnant.
I would like to know in which week I conceived.

Niming, 20~29 year old female. Ask Date: 2017/04/12

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, it is difficult to pinpoint the exact time of conception, but it should be around 2 to 3 weeks.
Wishing you good health.

Reply Date: 2017/04/12

More Info

To determine when you might have conceived, we need to consider the timing of your menstrual cycle and the ovulation process. Based on your last menstrual period (LMP) on February 3rd, we can estimate your ovulation date. Typically, ovulation occurs about 14 days before the start of your next period. Given that your menstrual cycle is usually around 28-34 days, ovulation likely occurred between February 17th and February 21st.

You mentioned having sexual intercourse on February 28th, March 2nd, and March 9th. Since sperm can live inside the female reproductive tract for up to five days, it is possible that intercourse on February 28th or March 2nd could have resulted in conception if ovulation occurred shortly after those dates. However, since you received a negative pregnancy test on March 18th, it suggests that conception likely occurred after that date, as the hormone human chorionic gonadotropin (hCG), which is detected by pregnancy tests, typically takes time to build up in the body after implantation.

You received a positive pregnancy test on April 9th, which indicates that by this time, enough hCG had built up in your system to be detected. Given that your doctor estimated you were about 4-5 weeks pregnant at that time, it aligns with the timeline of conception occurring around late March. This would suggest that you likely conceived around the time of your last sexual intercourse on March 9th, with implantation possibly occurring shortly thereafter.

In summary, based on your menstrual cycle and the timing of your sexual activity, it is likely that you conceived around early March, with a more precise estimate being between March 9th and March 12th.
It's important to note that pregnancy tests are most accurate when taken after a missed period, as this allows for the hCG levels to rise sufficiently for detection. If you have any further concerns about your pregnancy or if you experience any unusual symptoms, it is advisable to consult with your healthcare provider for personalized advice and care. Regular prenatal check-ups are essential for monitoring the health of both you and your developing baby.

Similar Q&A

When Did I Conceive? Understanding Pregnancy Timing and Menstrual Irregularities

I was supposed to get my period on February 25, but it didn't come. Since my menstrual cycle has always been irregular, I didn't take a pregnancy test until April 4, when I found out I was pregnant. I then went to see an obstetrician, who said I was already over 2 month...

Dr. Huang Jianzhong reply Obstetrics and Gynecology
Originally, my period was due on February 25, but it didn't arrive. Since my menstrual cycle has always been irregular, I didn't take a pregnancy test until April 4, when I found out I was pregnant. I then visited an obstetrician, who informed me that I was already over...

Understanding Pregnancy Testing: When Can You Detect Pregnancy After Intercourse?

Hello doctor, I would like to ask, I used condoms throughout on December 30, and on January 22, I still tested negative for pregnancy. What is the likelihood of pregnancy? I tested positive for pregnancy on January 26; when approximately did conception occur?

Dr. Huang Yiwen reply Obstetrics and Gynecology
Hello Ms. Pearl: The urine test on January 22 showed no pregnancy, but the test on January 26 indicated pregnancy. This is commonly encountered in outpatient settings, as most cases involve late conception where the levels of hCG (human chorionic gonadotropin) in the body have no...

Can I Get Pregnant? Understanding Your Fertility Timeline

Hello doctor, I reported my menstrual cycle on March 18, had intercourse on March 29 and again on April 5. Is there a chance I could be pregnant? When is the best time to take a pregnancy test?

Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, a pregnancy test should be taken at least 12 days after conception for accurate results. If your period is more than a week late, it is advisable to consult a gynecologist. Wishing you good health.

Understanding Pregnancy Chances: When to Test and Symptoms Explained

Hello Doctor, I had sexual intercourse on February 28th and experienced ejaculation inside. I took pregnancy tests on March 3rd, March 6th, and March 13th, but all results showed one line. I would like to ask: 1. How long after conception can a pregnancy test typically detect pre...

Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, a pregnancy test should be taken at least 12 days after conception for accurate results. The chances of pregnancy are low, so it's best to use contraception beforehand. If your period is more than a week late, consider consulting a gynecologist. Wishing you good healt...