size of bump compared to weeks of gestation - why is it important?

[Wills]

I'm curious about this one.

Every midwife visit she measure's my bump in centimeters. At 24 weeks I had a womb measuring 24cm. Since then the two figures have gradually diverged. Today at almost 31 wks I now measure just 29cm. She immediately said not to worry - which I'm not because I'm not sure why she does it. I keep meaning to ask her what value it is giving however I normally engrossed in other questions.

So does anyone know? If its not a problem then why bother? Surely a midwife could make approximate visual guesses? Also to me a roomful of pregnant women all around the same period will all be completely different sizes, some sticking out, some flatter but wider. So why measure?

[SoupDragon]

No idea! I have only been measured with a tape measure once, by a trainee "consultant" at the hospital who said "This isn't done much any more but I like to." He didn't say this in a wierd way BTW, just saying that it was a check he liked to do!

[musica]

I've been measured every appointment - I think the two numbers are supposed to be the same....but I agree, people's bumps are so different! I think it is the height of the fundus they are measuring, but maybe mears or leese can shed some light!

[Oakmaiden]

After about 20 weeks of pregnancy the fundal height (which is the length from the pubic bone to the top of the uterus) in centemetres is on average the same as the length of gestation, and in theory this is the case until 36 weeks (so at 22 weeks your fundal height is 22cm, and at 36 weeks it is 36cm).

The reasons this can be important are that "abnormal" growth can be indicative of problems inside the uterus - perhaps the baby is growing more or less than is usual, or perhaps there is more or less amniotic fluid, or perhaps there is more than one baby - all of these things are obviously useful to know, so that appropriate action can be considered. And so some midwives will get out a tapemeasure - but this of course is not very accurate - if you are well padded it can be hard to pinpoint exactly the top of the pubic bone, and the top of the fundus - even a small error makes a difference in what is not a large measurement anyway - and sometimes a full bladder can push up your uterus making it seem bigger than it otherwise would. Other midwives will just "gestimate" the fundal heigth by palpating your stomach and "eyeballing" how many "fingers widths" the top of your uterus is from your bellybutton or ribcage. I prefer this method - after all it is a tricky to get precise measurement, and more importantly it DOESN'T REALLY MATTER if it is a couple of centimetres out. Near enough is good enough - if in the eyes of an experienced midwife I look about the right size for my dates then I don't really feel the need for her to measure me precisely! And of course everyone IS different, and there is a certain amount of leeway to allow for different growth rates without it being a problem.

Anyway - was that too muchinformation? Or not enough? Basically, don't worry about it. The measurement is certainly within "normal" parameters.

[princesspeahead]

also I was measured today as two cm ahead of my dates, which my mw said was because the baby was currently lying breech, therefore quite high up and not head down in my pelvis, which makes the fundus longer. if that makes any sense! so the measurement can vary depending on the position of the baby at the time...

[Marina]

I think Oakmaiden and pph have said it all really, Wills. I asked the bereavement midwife about this when panicking about polyhydramnios (too much fluid meaning big bump and I was all-clear on that one as well ) and she once saw a mini-teaching session involving a student midwife, an SHO and a very experienced community midwife who all measured a game volunteer client "blind". Using the same tape measure they all had a different bump measurement...so who was right?
If your little one is part-engaged at 32 weeks, then there is going to be a little less bump to measure.
My m/w also told me that up to 3cm either side would not worry her in the slightest, especially if it was consistent for the client. Over 3cm and she might get some extra checks done if it suddenly changed.
PS She also said polyhydramnios at around 33 weeks would probably mean plus 9cm or something really quite marked, in case I have inadvertently spooked anyone...

[mears]

It is not the practise at our unit to measure bumps with measuring tapes. Agree with oakmaiden's postfor the reasons for it.

[eidsvold]

It helps - although I was only measured once during my pregnancy - towards the end the midwife - had she been measuring, would have seen that my bump actually decreased. A routine ultrasound ( having them regularly at the end of the pregnancy for another reason) showed that I had lost amniotic fluid ( unbeknown to me- just felt like I needed to wee a lot and lets face it - when one is 35 - 37 weeks pregnantwe do) and my baby was at risk. The upshot of that was just over an hour later my daughter was being born by emergency caeserean. I feel that the midwife would have noticed that the growth had slowed/stopped and it would have been monitored. My daughter was born at 37 weeks - within the 'normal' time frame but was known to not have been receiving quality nutrition from the placenta for at least two weeks.

So in a round about way - measuring is important. I realise some people have variations but it is important to be checked.

[Oakmaiden]

Oh, the midwife should check every time you see her - it is just that measuring with a tapemeasure is so inaccurate anyway there is little point in doing it. It is just as accurate to estimate from palpation.