Measuring 3 weeks ahead at 36 weeks - slightly concerned

[slylives]

I am 36 weeks and yesterday my midwife mentioned that my belly has suddenly "jumped" from 35 to 39cm. I also had an ultrasound to see if the baby is head down (which he/she is, thankfully) and the baby's head circumference was also measuring at week 39. I know that weight predictions can be wildly off, but my midwife estimates that baby's current weight is around 8lbs.

Ordinarily this wouldn't bother me - my daughter was 9lbs 9oz and was born vaginally without too much trouble (although I was ripped to shreds.) But I read another post about someone measuring significantly ahead and a few people enquired about the possibility of polyhydramnios . Which I then googled, and am now panicking about. Particularly as I have had a number of losses so my general anxiety level is high anyway.

Would excess amniotic fluid have shown up on the (admittedly quick) ultrasound? Would you be concerned? Part of me thinks that if the ultrasound also suggests a 39-weeker, it may just be a big baby. Would there be more cause for concern if my belly measured large but the ultrasound showed an average-size baby?

[Momsteader]

I wouldn't be concerned. The excess fluid would DEFINITELY have shown on the US. If there was more than usual, the tech would have noted it. At this stage in pregnancy, an US, even a quick one, they would note low or high fluid as it's very obvious. If babe measured 39w and that was your measurement, I'd not be concerned. 

Yes, US can be inaccurate for weight, but depending on the tech, it can be very accurate. I had many, many US with the twins and they were on to within ounces of their birth weight from the US the day before. 8 lbs for a baby measuring 39w doesn't sound horribly huge, and since your other LO was 9 lbs 9 oz, probably right on track.

[Lidamama84]

I wouldn't worry either; if your midwife is not concerned. There are other factors besides just size that matter, but you can always bring up your concerns with your midwife. In the U/S report they probably measured the fluid levels.  I am currently 36w and I am measuring 31w. Not an issue, just a small babe, but my midwife does want to do weekly ultrasounds just to make sure everything stays on track. I have also read that the larger the baby, the less accurate the ultrasound measurements towards the end of pregnancy.

[littleteapot]

Measurement is not an exact science, and can change depending on care provider, baby's position, and a number of other factors. Don't worry too much about it.

Depending on who measures me, they come up either right on, or FIVE CENTIMETERS too small. That's a huge difference! The reason? Baby is stuck under my ribs and the top of my fundus can no longer be felt. So now it depends on the skill and experience of the care provider. :)

With my last baby I measured 5-6cm ahead the entire way through the pregnancy, and he was born a healthy, happy 9.5lb baby boy. If your'e worried about tearing with a large baby, go for a waterbirth!! Also, stay off your back, in upright positions, stay hydrated, and go with your body instead of purple pushing. Lots and lots of things can help prevent tearing. :) I had a slight tear with my first (6# 14oz) but not even a swollen vulva with my third (9.5lb!).  ;)

[amaayeh]

I have measured anywhere from 2-5 weeks ahead this pregnancy and was checked for excess fluid.  Nope.  Big baby?  Nope.  Nothing really explainable, but I'm not worried.  I'm currently measuring about 3 weeks ahead.  Last time midwife checked me, she said I was measuring 5 weeks ahead and then asked me to adjust myself on the sofa and measured again...only two weeks ahead.  It can vary greatly by your exact position.