Pregnancy Weeks: Menstrual vs. Implantation Bleeding Confusion

In the pregnancy cycle, it is uncertain whether the last menstrual period was an actual menstruation or implantation bleeding?

Is the gestational age calculated by the hospital's ultrasound accurate? If there is an error, could it be significant? Currently, I am at 27 weeks, and everything seems normal, but I am uncertain if my last menstrual period was actually a miscarriage or a regular period since it only lasted two to three days and was lighter than usual.
I am concerned that it was not a true period.
I had my period on February 17 for four days, then on March 21 for about two to three days, and I did not have a period in April.
I took a pregnancy test on May 5, which, based on the March 21 date, would indicate I was 6 weeks and 1 day pregnant.
The ultrasound did not show anything, and I worry that the bleeding in February and March might have been implantation bleeding.
I have previously experienced periods that lasted two to three days, and my cycle is not very regular, but is it possible to have bleeding for two months? Was the bleeding in March a true period? It seems possible that I could have conceived in January, experienced bleeding in February, and then again in March.
Is it possible for implantation to take that long? Could I have conceived in January, especially since my boyfriend at that time is not the father of the child? Did the doctor calculate the gestational age based on the first day of my last menstrual period on March 21, or was it assessed by a computer?

MM, 20~29 year old female. Ask Date: 2020/09/25

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, it should be as the doctor mentioned.
Wishing you good health.

Reply Date: 2020/09/25

More Info

Understanding the nuances of pregnancy dating can indeed be confusing, especially when considering factors like menstrual bleeding and implantation bleeding. Let's break down your concerns regarding the accuracy of ultrasound dating, the implications of early bleeding, and how these factors interplay in your current pregnancy.

Accuracy of Ultrasound Dating
Ultrasound is a reliable method for dating a pregnancy, particularly in the first trimester. The accuracy of ultrasound measurements is generally within a week, especially when performed before 13 weeks of gestation. After this period, the accuracy can decrease slightly due to variations in fetal growth rates. In your case, being at 27 weeks, the ultrasound should provide a fairly accurate estimate of your due date, assuming it was performed early in the pregnancy.

Menstrual vs. Implantation Bleeding
You mentioned experiencing bleeding in February and March, which raises the question of whether these were menstrual periods or implantation bleeding. Implantation bleeding typically occurs around the time your period is due, but it is usually lighter and shorter than a normal menstrual period. If you had bleeding that was lighter and shorter than your usual menstrual flow, it could potentially be implantation bleeding rather than a true menstrual period.

Given your history of irregular cycles and the uncertainty surrounding your last menstrual period, it is possible that the bleeding you experienced in February and March could have been related to implantation rather than a typical menstrual cycle. This is particularly relevant if you suspect conception occurred in January.

Possible Scenarios
1. If the February bleeding was implantation bleeding: This could mean that you conceived in January, and the ultrasound dating based on your last menstrual period (LMP) of March 21 might not align perfectly with the actual conception date. In this case, the ultrasound would be more accurate in determining gestational age.

2. If the February and March bleeding were menstrual: If these were indeed menstrual cycles, then the ultrasound dating would be based on the LMP, and your current gestational age would be accurate.

Concerns About Early Bleeding
Early bleeding in pregnancy can be concerning, but it is not uncommon. Many women experience some form of bleeding in early pregnancy, and it does not always indicate a problem. However, it is essential to monitor the situation closely. If you have any significant bleeding or cramping, it is crucial to contact your healthcare provider for further evaluation.

Conclusion
In summary, the ultrasound dating is generally reliable, particularly in the first trimester. Your concerns about the nature of the early bleeding are valid, and it is essential to consider the characteristics of that bleeding when discussing your pregnancy timeline with your healthcare provider. If you are still uncertain about the dating or have concerns about your pregnancy, I encourage you to have an open discussion with your obstetrician. They can provide clarity based on your specific situation and medical history, ensuring that you receive the best care possible as you progress through your pregnancy.

Similar Q&A

Is It Menstrual Bleeding or Implantation Bleeding? Understanding Your Cycle

Hello, doctor. My menstrual cycle is between 23 to 28 days, and I have the impression that my period only comes early and never late. My last period started on April 28, and this month I had a significant amount of bright red blood on May 29 (I noticed some spotting before bed on...

Dr. Zhang Kunmin reply Obstetrics and Gynecology
Hello, the questioner: Vaginal bleeding is not always indicative of menstruation; some individuals may mistake early pregnancy bleeding for their period. It is not possible to determine whether one is pregnant based solely on subjective symptoms. Therefore, if you are uncertain w...

Implantation Bleeding or Menstruation: Understanding the Differences

Hello Doctor: My period was supposed to start on the 13th, but it began today on the 9th. My last period was from September 16 to September 21. On the 21st, I had sexual intercourse, but it was only external friction without penetration. I took ovulation tests the day before and ...

Dr. Lin Lixuan reply Obstetrics and Gynecology
If there was sexual intercourse on September 21 and pregnancy occurred, it should be detectable by October. Therefore, the current bleeding is likely normal menstrual bleeding. If there are any concerns, please consult a nearby obstetrics and gynecology clinic for examination and...

Understanding Implantation Bleeding vs. Menstrual Cycle: Key Insights

Hello Doctor, I am 184366. We took pregnancy tests on July 21 and July 28, both showing a single line. My girlfriend experienced breast engorgement around July 24 and 25 (which has never happened before her period). On the night of July 27, she had a small amount of bleeding, and...

Dr. Zhang Kunmin reply Obstetrics and Gynecology
Hello, based on your description, it is not possible to confirm whether you are pregnant. The absence or presence of pregnancy cannot be determined solely by subjective symptoms. It is recommended that you consult an obstetrician-gynecologist to arrange for relevant tests to conf...

Understanding Implantation Bleeding: Signs and Symptoms Explained

Hello doctor, my menstrual cycle is 31 days and very regular. My period did not arrive on the expected day, and I tested for pregnancy that day with faint lines appearing on both tests, although the lines developed slowly. However, two days later, I experienced slight spotting an...

Dr. Huang Yuande reply Obstetrics and Gynecology
In early pregnancy, it is normal for a small number of individuals to experience light bleeding, and it is usually sufficient to rest and monitor the situation. There are many reasons for bleeding, and implantation bleeding is just a general term.