Normal Fetal Heart Rate, Gestational Age, Crown Rump Length

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Normal Fetal Heart Rate, Gestational Age, Crown Rump Length

Postby chorse37 » Fri Nov 06, 2015 12:33 pm

Hi Ladies,

I want to put some charts out there to help realize if your results are normal or if you should be concerned when doctors are less than helpful. I am a scientist but I did not work on this study; the original paper can be found here: http://www.karger.com/Article/Abstract/319589 If you're into that kind of thing I highly recommend you read through it.

Some background for why I'm doing this: I had a missed miscarriage a few months ago that was preceded by an ultrasound with heartbeat. The general advice I had read on forums and websites all pretty much say that once you see the heartbeat, you can stop worrying. That's why I was confused when my OB said I needed to come back for another ultrasound in one week. She didn't say I should start preparing for a miscarriage or even why my results were concerning, just that they wanted to "recheck". Being a scientist, I wasn't satisfied with that and started reading all the material I could get my hands on. From what I found about fetal bradycardia (slow heartbeat) I had an 85% chance of miscarrying. At the followup, there was no heartbeat and it was diagnosed as a missed miscarriage. I'm a firm believer that knowledge is power. I feel like if I hadn't been expecting the loss it would have been harder to come to terms with.

I'm not trying to say if you fall inside the "normal" lines you will have a problem-free pregnancy or that if you fall outside the lines you will definitely miscarry, but at least try to take comfort in the data. It helped me, at least.

Below are graphs showing the relationships between several metrics taken during a routine ultrasound in early pregnancy. I would recommend asking the tech or your OB for all your measurements (I was only given gestational age and heart rate). All of the data from this study were from nearly 4700 pregnancies that resulted in healthy babies. The green line is the average, or "normal" value, and the red and orange lines are the 95% confidence limits (meaning 95% of healthy pregnancies fall between them). If your gestational age measures "behind" or "ahead", use the date given by the measurements, not your previous estimate. For example, if you think you are 6w5d but the tech says you are measuring 7w0d, use 7w0d, or 49 days, as your gestational age. Better yet, if you're sure of your gestational age and they give you a new one, pop it into the GA-CRL chart and see how you stack up. Usually they get this new approximation from the crown rump length, because it has such a well-defined relationship with age.

If anyone has questions, I'll try my best to answer them, keeping in mind I am not a medical doctor.

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Me/DH: 28; together since 2006
TTC #1
BFP 7/29/15 Due 4/09/16 :angel: missed MC 9/1/15
BFP 10/28/15 Due 7/10/16 IDENTICAL TWINS! :angel: :angel: missed MC 12/13/15

BFP 03/05/16 Due 11/13/16

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Re: Normal Fetal Heart Rate, Gestational Age, Crown Rump Len

Postby FrostedFuji » Fri Nov 06, 2015 3:46 pm

This is really awesome, thank you for putting it together & sharing!
Fuji: 28; H: 29

Our first baby!
Willow Del, born at 37,5 on 12/8/15
5 lb, 7.5 oz; 18.25" long
Former code name Little Jedi

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Re: Normal Fetal Heart Rate, Gestational Age, Crown Rump Len

Postby alecita1987 » Sat Nov 07, 2015 6:07 pm

Thanks for sharing!

I also did a lot of research because of my missed miscarriage. I'm a RN so I do have medical background but I don't specialize in OB and actually disliked my OB class in nursing school lol. But I've learned so much and have so much respect for the science behind this whole deal of making a baby. It's so complicated but yet fascinating. I've learned to not take anything for granted and my mom says that I know way too much and that has not let me fully enjoy my pregnancies, but I actually feel empowered by my knowledge and mentally prepared for whatever outcome my pregnancy might have (obviously always hoping for the best).

These charts made me real happy cause according to them my baby was measuring well above the 50th % at the u/s a few days ago. Very reassuring after never even seeing a HB during my first pregnancy.
Me: 29, DH: 28
DS: 14 months old

BFP! 4/21/15 -> :angel: MMC @ 10w (6/6/15)
BFP! 10/1/15 -> DS born 6/9/16. My RAINBOW Baby!
BFP! 6/26/17 -> EDD 3/8/18 :sticky:

Ultrasound on 8/1/17 @ 8w5d :hb: 172 bpm

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