HCG Levels and Pregnancy Weeks: What You Need to Know

Is the HCG level accurate, and how does it relate to the weeks of pregnancy?

Hello, my last menstrual period started on February 28.
My average menstrual cycle is between 35 to 36 days.
I used an ovulation test on March 18, which showed two lines of equal darkness (with one faint line on March 17 and one faint line on March 19).
On March 31, I first tested and saw faint lines.
My daily temperature rose from the high-temperature phase of 36.5x degrees to 36.77 degrees, and in the last week and a half, it has been maintained around 36.93 to 37.04 degrees (only one day was lower at 36.86 degrees).
On April 2, I went to the obstetrics and gynecology department for an ultrasound, but nothing was seen.
However, after a pregnancy test, the doctor confirmed that I was pregnant (with faint lines).
On April 6, I returned to the obstetrics and gynecology department, where the doctor drew blood to check my HCG levels, which reported a level of 34.
Two days later, on April 8, I had another blood test, and the report showed 36.9.
The doctor informed me that it could be an ectopic pregnancy or a failing embryo, as the HCG levels did not double.
That same evening, I visited another obstetrician, who said that since I have a longer menstrual cycle, I just became pregnant, and if calculating the weeks of pregnancy, I would only be 3-4 weeks along.
He mentioned that he would not reference the HCG levels and advised me to return in 1-2 weeks.

Could you please help me calculate how many weeks and days pregnant I am as of April 10? How many weeks since conception have I been? Is it really abnormal to have such low HCG levels? I am very worried...
Thank you.

Xiao Di, 30~39 year old female. Ask Date: 2016/04/10

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello, based on your description, there are currently two possibilities: anembryonic pregnancy or ectopic pregnancy.
Since the hormone levels are not high and there is no significant increase, the immediate risk is not high.
It is recommended to follow up with your physician as advised.
If you experience severe abdominal pain or heavy bleeding, please seek medical attention at an outpatient clinic or emergency room immediately.
Thank you! Wishing you safety and health.
Dr.
Chang

Reply Date: 2016/04/10

More Info

Understanding HCG Levels and Pregnancy Weeks: What You Need to Know
Based on the information you've provided, let's break down your situation regarding your pregnancy timeline and HCG levels. Your last menstrual period (LMP) started on February 28, and considering your average cycle length of 35-36 days, ovulation likely occurred around March 17-18. This means that by April 10, you would be approximately 5 weeks pregnant, counting from the first day of your last menstrual period.
To clarify, pregnancy is typically calculated from the first day of your last menstrual period, not from the date of conception. Therefore, if we consider your LMP, you would be about 5 weeks along as of April 10. If we were to calculate from the date of ovulation (around March 17-18), you would be about 3 weeks pregnant. This discrepancy is important because it can affect how HCG levels are interpreted.

Regarding your HCG levels, the first test on April 6 showed a level of 34 mIU/mL, and the subsequent test on April 8 showed a level of 36.9 mIU/mL. In early pregnancy, HCG levels typically double every 48 to 72 hours. The fact that your levels did not significantly increase raises concerns about the viability of the pregnancy. Low or slowly rising HCG levels can indicate a potential miscarriage or an ectopic pregnancy, which is when the embryo implants outside the uterus.

However, it's also important to consider your longer menstrual cycle. A longer cycle can mean that ovulation occurs later, which may affect the timing of HCG levels. The second doctor you consulted suggested that you might be very early in your pregnancy, which could explain the lower HCG levels. In cases of longer cycles, HCG levels may not follow the typical doubling pattern seen in shorter cycles.

In terms of what is considered a normal HCG level, it varies widely in early pregnancy. For example, at 3 weeks, HCG levels can range from about 5 to 50 mIU/mL, and by 5 weeks, they can range from 18 to over 7,340 mIU/mL. Your levels are on the lower end of the spectrum, which is concerning, but it's crucial to monitor how they progress over the next few days.

If you experience any severe abdominal pain, heavy bleeding, or other concerning symptoms, it is essential to seek immediate medical attention. Otherwise, following up with your healthcare provider in 1-2 weeks, as suggested, will be critical to assess the situation further. They may recommend additional blood tests to monitor HCG levels and possibly an ultrasound to check for the presence of an embryo in the uterus.

In summary, while your HCG levels are low and not rising as expected, the timing of your ovulation and the length of your menstrual cycle could play a significant role in this. Continue to monitor your symptoms and follow your doctor's advice for further evaluation. Early pregnancy can be a time of uncertainty, but with careful monitoring, you can gain a clearer understanding of your situation.

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