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3chords' collection of BETA/HPT FACTS

3chords

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Hi all,

I compiled this research over a long time while we were (and still are) trying to grow our family. I often got frustrated on forums when people would say things that really aren't necessarily factually true. In a past life I worked in biomedical research so the geek in me enjoyed this exercise. I hope that this helps people who are wondering about their beta levels, tests, fetal heart rates, etc. It is long but could be handy as a tool and I hope it helps those who have questions. I'll cross post in other subforums since not everyone comes on here.

Beta HCG Rates of Increase
• Not as much research exists on this topic but there are a few things that carry consensus, summarized below.
• Doubling rate = 100% rise. The closer you get to 100% rise in 48 hours, the better but a 2009 Shamonki et al. study showed that there is “no further enhancement in live birth rates” with increases greater than 100%. Meaning that if your beta “just” doubles, it’s good enough, your pregnancy outcome isn’t going to be any better if it triples or quadruples.
• A 2016 Sung et al. study looked at doubling rates between 12DPO and 14DPO for fresh and frozen IVF cycles. In fresh cycles, if your beta increased by a factor of at least 2.56 between 12DPO and 14DPO, the odds of ongoing pregnancy were about 74% - meaning for example if your beta at 12 DPO was 50, a 2.56 fold rise would be 128 at 14DPO. In frozen cycles, the beta would have to increase by 2.38 to give you an 82% chance of ongoing pregnancy.

Beta HCG thresholds using Clearblue Digital With Weeks Indicator
• ClearBlue had to file a 510(k) data sheet with the Food & Drug Administration. It is available online and it states the thresholds of detection for various levels. I have summarized below, you will see two numbers for each indicator – the first number indicates the LOWEST possible beta that will show you a particular result and the second number indicates the lowest beta at which ALL women in the study got the particular result.
• 1-2 weeks: low threshold 10.2; all women 17.7. Meaning no woman with a beta lower than 10.2 got a positive pregnancy 1-2 weeks result and no woman with a beta of 17.7 or higher got a negative pregnancy result.
• 2-3 weeks: low threshold 121; all women 504.
• 3+ weeks: low threshold 2103; all women 4176.

Pregnancy Outcomes Based on Early Beta
• Importance of high early betas
o The truth is that early implantation is extremely important in ongoing pregnancy and live births. Literally every single study out there supports this fact. It may be surprising to many people just how high the betas need to be early on.
o A 2016 Chen et al. study looked at betas at 10DPO/7dp3dt/5dp5dt and concluded that women with a beta >26.6 on this day had a 76% chance of ongoing pregnancy.
o A 2016 Sung et al. study looked at betas at 12DPO and 14DPO as well as the
o The most comprehensive of studies appears to be a 2001 Poikkeus et al. study that looked at beta HCG levels at 12dp3dt (equivalent of 15DPO or 10dp5dt). The conclusions are very interesting. Notably, on that day no ectopic pregnancy had a beta that was higher than 86 and no chemical pregnancy had a beta that was higher than 106. I’ve put down the rough number sets for: miscarriage/singleton/twin pregnancy % odds on this day as follows (when they do not add up to 100 it’s due to the rest being ectopics or chemicals): Beta 5-14: 10/4/0; Beta 15-28: 25/1/0; Beta 29-45: 32/30/1; Beta 45-66: 31/45/3; Beta 67-86: 30/57/5; Beta 87-106: 15/75/10; Beta 107-131: 23/67/20; Beta 132-169: 5/75/15; Beta 170-220: 4/66/30; Beta 221-683: 5/45/50.
o Lessons learned: Miscarriage rates are very low (5%) and ectopic and chemicals are nonexistent at a beta of 132 or higher at 15DPO.

Vanishing Twin
• On average, the beta of singletons, twins and vanishing twins will at least double in 48 hour period. In a 2013 study by Brady et al. the average rate of increase of beta in vanishing twins is lower (114%) than singletons (128.8%) and twins (125.4%).
• Lesson learned: while beta hcg levels with vanishing twins rise at a slightly slower rate than singletons and twins it DOES double, therefore abnormal beta hcg level increases should NOT be attributed to a vanishing twin.

Ectopic Pregnancies
• Studies agree that no single level of beta HCG is diagnostic of ectopic pregnancy and monitoring HCG levels is also not particularly predictive as they vary widely. In a 2016 Surampudi et al. study of 48 hour beta HCG repeats in women who had ectopic pregnancies and a beta of less than 1500 at the time of blood draws showed the following: (1) 22.5% of women plateaued – had neither an increase or decrease; (2) 26.8% had a decrease of 15% or more; and (3) 47.9% had an increase of 15% or more and of this group almost ¼ of the women had a doubling which would be considered “normal”.
• Lesson learned: ectopic pregnancies can only reliably be diagnosed via ultrasound.

Early Fetal Heartbeats
• There is scientific consensus that slow embryonic heart rate in the first trimester is an indicator of poor pregnancy outcome.
&#8226; Doubilet et al. have published a number of studies looking at very early embryonic heart rates of 6-7 weeks gestation. The odds of miscarriage based on heart rates of embryos which are 6+2 weeks of gestation or younger are: 78% if heart rate is less than 80bpm, 46% if heart rate is 80-89bpm, 17% if heart rate is 90-99bpm and 9% if hear rate is >100bpm. The odds of miscarriage based on heart rates of embryos that are 6+3 to 7 weeks of gestation are: 78% if heart rate is <100bpm, 46% if heart rate is 100-109bpm, 17% if heart rate is 110-119bpm and 9% if heart rate is >120bpm.
&#8226; Lesson learned: embryonic heart rates are highly predictive of pregnancy outcomes.
 
Very interesting, it is always good to see figures actually backed up with evidence.
 
Very cool although my personal experience with my last 4 pregnancies contradict a lot of it!
 
Very cool although my personal experience with my last 4 pregnancies contradict a lot of it!

Sure, I think we all could find something, but that's the point of scientific research, it looks at very large sample sizes and our experiences are really just anecdotal.
 

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