Umbilical artery flow - Low CPR ratio

[MissHoney85]

Hi all, bit of a complex story here but I'd really appreciate any advice from someone who has been in a similar position or knows about these things.

I'm 34 weeks and had a growth scan today as my bump was measuring small. Funnily enough the baby turns out to have the opposite problem - on the scan she was measuring on the 97th centile for abdominal circumference. I've been referred for a GTT test on Monday.

My question though is about the umbilical artery flow measurements. These weren't mentioned at the time, but on looking at my notes afterwards I noticed that they were really low. My community midwife got the sonographer to call me and he explained that low is actually good for the two artery measurements, and what they are looking for is the ratio of the two measurements to be above 1. My CPR ratio was 1.38. Having made the error of googling this afterwards, it seems that 1.38 is still really low (4th centile) and that a low measurement here has some quite worrying implications as a predictor of poor outcomes.

There doesn't seem to be a lot of information out there but most of it seems to be in the context of low CPR ratio in babies that are small for Gestational Age, which mine is not. It still feels scary to be on the 4th centile though. Should I be worried, maybe push for a consultant to look into it? Nothing about this pregnancy seems to add up! I'd really appreciate any advice or experience.

As your midwife has said, a low number here is really good. It basically means that the blood flow from you to the placenta is really strong, and the placenta isn’t having to work really hard to get the blood in.
I have the opposite problem and have a very high score due to low PAPP-A. My arteries are very thin and brittle, so my placenta has to work very hard to get enough blood in, so the pressure is high. This causes issues as the placenta can deteriorate quicker.
Your current centile number being low is only an issue if the growth has slowed since the last scan. You could just be having a small baby, who has stayed small the whole time. But growth scans are notoriously inaccurate. Try not to worry.

Low is definitely good (I used to work in that area). If it's plotted on a chart, even if it's below the average line we don't worry. High is where the problems can start. Honestly you have enough going on at this stage without adding extra things in to worry about. Your midwife and the poster above are right here.

Hi - I have to respectfully disagree with the above two posts. You’re right, cerebroplacental ratio/CPR on the 4th centile is abnormal - anything

@TenThousandSpoons0 that is really helpful, thank you so much. The 1.38 figure is what's on my notes. Interesting that the measurements can be inaccurate if the baby is moving, as mine was wriggling at the time and it took the sonographer a couple of goes to get it. I think I will ask my midwife if there's any chance of getting my notes under a consultant's nose just to double check. Thank you!