Blood test vs LMP?

[adellademona]

On 10/28/15 I took 2 tests and both were positive! I went to the doctor the following day and she confirmed for me that it was a bfp! She also took blood.

According to my LMP I am 6 weeks pregnant. My LMP was 9/21/15. According to her bloodwork I am approximately 3 weeks pregnant. For some reason this doesn't add up for me. Does this sound normal?

Should I be worried at all?

 

[AndreZZ]

You may have ovulated late which would make you less far along than you think. You could request a second blood draw to make sure your hcg levels are rising appropriately.

 

[adellademona]

I just thought pregnancies weren't really detectable until about 4 or 5 weeks on POAS. Although that shows what I know.

I dunno, I have the cramps, nausea, moodiness, sensitive super smell, and extreme fatigue associated with 6 weeks. But I dunno. I'm just anxious to get to the first OB appointment to make sure everything is going okay.

 

[AndreZZ]

At this point the only way they can tell if the pregnancy is heading in the right direction is through bloodwork. The bloodwork would also be good for your OB too. It would t hurt to do it just to put your mind at ease ☺.
Glad you're having nice symptoms that's always good..sometimes those symptoms can creep up before 6 weeks.

Did your doc give you a number for the hcg level in your bloodwork?

 

[minties]

HCG results don't really tell you how far along you are, they vary too wildly. Congratulations on your pregnancy

 

[laila 44]

Only way to know what's going on is to do a repeat beta in 48 hrs xx

 

[adellademona]

No, she didnt give me any numbers. In the meantime I'm not really spotting any or having any ridiculously painful cramps...so I am going to try and not worry.

My cycle has been off the last month - I was actually late for my last period and it was brought on a few days after my regular gyno exam. She tested me when it was late that time and it was negative. This past month I was expecting my monthly around the 21st and for a minute believed it had started - I spotted super light for a couple days and then it stopped. At that point I knew I should test because I suspected I was pregnant. And I was right! Since my cycle is off there's really no way to tell until I get into the OB and get an ultrasound. This one is my first so I'm really floundering around in the dark!

 

[Scout]

Hcg varies too much to use it to date a pregnancy. With daughter, my first blood draw was at 4w6d according to LMP. The number came back at over 18,000 which put me in the 6+weeks range according to online hcg charts, but a scan the following week confirmed that I was 4w6d when I had the blood drawn. I wouldn't worry at all at this point. Plus, only one hcg blood level doesn't give any real information anyway. Good luck and congratulations!

 

[Lues]

really neither a blood draw nor your last missed period is a good indicator of how far along you are.

You might have a perfect 28 day cycle, but you might have a short or long luteal phase (period between ovulation and af), so you may not be ovulating right in the middle.

HCG levels rise at different rates for different people (and even the same people different pregnancies). Most tests won't show up until it's over 15 or 25 (some as early as 10), but that could be 10 DPO for one person and 16 or 17 DPO for another.

I assume this was your general doctor? Sometimes it's amazing how little they know about pregnancy. With a single blood draw there is totally no way to date you.

My guess would be you're probably under 50 and she's using this "normal range chart" or something similar:

3 weeks LMP: 5 – 50 mIU/ml.
4 weeks LMP: 5 – 426 mIU/ml.
5 weeks LMP: 18 – 7,340 mIU/ml.
6 weeks LMP: 1,080 – 56,500 mIU/ml.
7 – 8 weeks LMP: 7, 650 – 229,000 mIU/ml.


So if you're under 50 she's probably thinking "under 50 is the normal for the 3 week range". But as you can see, it can also be "normal" for 4 or even 5 weeks along.

I would bet you're somewhere in the middle, and either way it's nothing to worry about. I would agree with previous posters that a common standard is to test again 2-3 days later to check the doubling rate. But even this has nothing to do with dating you, it's just to be sure the number is going up appropriately.

Congrats on your BFP though!

 

[AndreZZ]

HCG results don't really tell you how far along you are, they vary too wildly. Congratulations on your pregnancy

Very true!

 

[AndreZZ]

No, she didnt give me any numbers. In the meantime I'm not really spotting any or having any ridiculously painful cramps...so I am going to try and not worry.

My cycle has been off the last month - I was actually late for my last period and it was brought on a few days after my regular gyno exam. She tested me when it was late that time and it was negative. This past month I was expecting my monthly around the 21st and for a minute believed it had started - I spotted super light for a couple days and then it stopped. At that point I knew I should test because I suspected I was pregnant. And I was right! Since my cycle is off there's really no way to tell until I get into the OB and get an ultrasound. This one is my first so I'm really floundering around in the dark!

You know what hun since your cycles have been off you prob just ovulated late...don't worry I'm sure all is well enjoy your pregnancy!

 

[adellademona]

You're all likely right! @AndreZZ, I'm almost 100% positive I ovulated late! My husband wasn't available for the deed during my projected ovulation window. So I'm sure I did.

I'm naturally a worrier. As far as I know I'm still pregnant. My first OB appointment is on the 17th. So I'm looking forward to that.

 

[Tesh23]

really neither a blood draw nor your last missed period is a good indicator of how far along you are.

You might have a perfect 28 day cycle, but you might have a short or long luteal phase (period between ovulation and af), so you may not be ovulating right in the middle.

HCG levels rise at different rates for different people (and even the same people different pregnancies). Most tests won't show up until it's over 15 or 25 (some as early as 10), but that could be 10 DPO for one person and 16 or 17 DPO for another.

I assume this was your general doctor? Sometimes it's amazing how little they know about pregnancy. With a single blood draw there is totally no way to date you.

My guess would be you're probably under 50 and she's using this "normal range chart" or something similar:

3 weeks LMP: 5 – 50 mIU/ml.
4 weeks LMP: 5 – 426 mIU/ml.
5 weeks LMP: 18 – 7,340 mIU/ml.
6 weeks LMP: 1,080 – 56,500 mIU/ml.
7 – 8 weeks LMP: 7, 650 – 229,000 mIU/ml.


So if you're under 50 she's probably thinking "under 50 is the normal for the 3 week range". But as you can see, it can also be "normal" for 4 or even 5 weeks along.

I would bet you're somewhere in the middle, and either way it's nothing to worry about. I would agree with previous posters that a common standard is to test again 2-3 days later to check the doubling rate. But even this has nothing to do with dating you, it's just to be sure the number is going up appropriately.

Congrats on your BFP though!

Very thorough and accurate advice! I agree with lues