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How reliable is the midwife's measuring tape?

(14 Posts)
dottytablecloth Thu 13-Nov-14 12:36:13

Slightly shocked as I'm 35+3 and have been in the average measurement category all through this pregnancy.

Went to see midwife today and she measures me at 30 weeks and below the 10th percentile.

Does this mean the baby has suddenly stopped growing or is there a chance she has got it wrong?

Feeling a little worried.

fasterkillpussycat Thu 13-Nov-14 12:40:58

Don't worry - I understand that these measurements can vary hugely depending on where the tape is placed. I was sent for an urgent growth scan when my bump measured off the chart. All was fine and the next midwife who measured me came up with a completely different figure. Have you been referred for a growth scan?

FaFoutis Thu 13-Nov-14 12:42:12

Completely unreliable and pointless in my experience. Don't worry on the basis of that.

dottytablecloth Thu 13-Nov-14 12:47:00

Yes I've been referred for a growth scan.

My last baby was very small at birth, placenta stopped working.

I was so happy about having a 'normal' sized baby this time and not to have people be shock when they saw baby for the first time.

DayLillie Thu 13-Nov-14 12:52:30

Baby's head engaging usually knocks a couple of centimetres or so off the measurement.

Hobby2014 Thu 13-Nov-14 12:54:07

I'm not sure of them either - does anyone know the point? I measured correct every time yet had an 11lb7oz baby, midwives kept telling me I was having an 8lb baby. Surely my measurements should have always been ahead or is this not the case?
they also didn't know he was breech but that's a different story

FaFoutis Thu 13-Nov-14 14:26:08

OP did the tape pick up that your last baby was small?

Mine was 4lb and according to the tape measured average all the way through.

DayLillie Thu 13-Nov-14 14:49:36

It is usually 1cm/week and the number of cm is supposed to be the same as the number of weeks.

When I was having twins, it was 20cm at 15wks, then +8cm most of the time, then +10cm after 30 weeks.

I am not sure if it can tell you how big the baby is, only that it is progressing and growing. It is quick and cheap!

It shouldn't really go down, but there are probably a whole host of reasons for that, other than the baby shrinking hmm, so it is just a sign that they should be taking some proper measurements. Hopefully the baby has just moved position or something similar.

ZenNudist Thu 13-Nov-14 14:55:01

Fundal height measurement notoriously unreliable. It depends on baby's position as well as other things.

Don't worry and DONT GOOGLE!

I had a small for dates reading and got myself so worked up about it then growth scan showed all normal. Ds2 born on 85th centile...

You'll be fine.

LordTumble Thu 13-Nov-14 16:53:12


I measured small for dates with my first baby and she was born 5lb7oz so relatively small but perfectly healthy.

This pregnancy I've been sent for growth scans and consultant appointments as a precaution. Had one this morning at 35 weeks and the midwife measured me at 29cms, second midwife measured me at 33cms and consultant measured me at 34cms, all within half an hour!

Growth scan showed amniotic fluid to be normal and a good blood flow through the umbilical cord so nobody is concerned. Hope your growth scan shows the same, as that is what counts and not the measurement.

PassTheAnswers Thu 13-Nov-14 16:56:21

Yy to differences in measurements. I've found it differs dramatically based on the individual doing the measurement- I've varied 2cms in the same week. Growth scan should pick up any potential problems more than a tape measure!

TarkaTheOtter Thu 13-Nov-14 17:01:21

I measured 3cm difference on the same day! It's bollocks.

DoingTheSwanThing Thu 13-Nov-14 17:08:50

Most units are using customised growth charts, it's not strictly a cm per week - it is useful (and validated, or else no one would be using it!) as a screening tool to pick up small or large for dates babies, and rapid shifts in growth velocity, but yes, decent margin of error - doesn't correlate particularly well with the actual weights on the other side of the chart though! Smoothness of curve much more important.

Just to mention a common misconception re loss of fundal height with engagement - that's actually not correct, since the total volume if baby/fluid etc isn't affected, just displaced, the growth should be maintained right up to the end (as per perinatal institute guidelines).

Op - very likely all is absolutely fine, don't panic!

Shelduck Thu 13-Nov-14 17:17:30

One MW told me it was like trying to guess the weight of a turkey that's wrapped in a duvet.

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