Cervical length measurements - shortened by 6mm

[Mamalog]

Just looking for some advice… I’ve been having scans on my cervix to check cervical length as I had a previous c-section at full dilation.

My scan at 24 weeks showed my cervix measuring 36mm which was fine, I didn’t have another scan till 29 weeks due to apparent issues in the clinic. At my 29 week scan my cervix had shortened to 30mm, they discussed putting me on progesterone pesseries but there would be nothing else they could do as I’m too far on, and just to keep my eye out for preterm labour signs etc. When ive googled it says that at 29 weeks it should still measure around 37 mm ish, but the doctor didn’t have much advice on what it should measure exactly at this stage as they don’t usually do the scans this late.

Firstly I’m just wondering if anyone knows anything about cervical measurements and what it should actually measure at this stage and when in pregnancy does cervix actually start to shorten for labour?

Also today baby has suddenly dropped, when I use my fingers to feel my pubic bone I can feel her hard head right there above my pubic bone and I have so much pressure there when I walk etc, getting lots of braxton hicks too. Should I be concerned that baby has dropped so low?

It's hard to say, mine shortened to 24mm at 24 weeks and I had progesterone until 36 weeks, DD was fully engaged at 31 weeks and cervix was soft, so I was told to keep off my feet as much as possible until 37 weeks, which I did, as soon as I stopped the progesterone I started to dilate, but still didn't go into labour until 40+5.

With my second I believe I was 30mm from around 21 weeks which the consultant wasn't worried about at all and said they'd only work if I went below 25mm, I was still o. Progesterone though due to my first pregnancy

I’m 29+1 today, I have history of recurrent miscarriage with one loss at mid term (14 wks) hence I was having cervical length measured this time. I had measurements 49 mm at 17 wks, 44 mm at 20 wks and 45 mm at 26 weeks and I was told at the last one that I’m now discharged and no longer need to be measured. I’m no means an expert of what the measurements are meant to be, however in my regular 28 week midwife appointment last week the midwife commented that the measurement was good and that they were only concerned if it was 25 mm or below.
I was on progesterone earlier in pregnancy until 16 weeks.

Thanks guys for replying. I was admitted to hospital with contractions every 2 minutes and when I was examined my cervix had shortened again, it’s slightly open but I have had a baby before so they said that could be normal (even though I was told it was fully closed a couple of weeks ago!). My contractions have now slowed down and are just very irregular I think I’m in slow labour and my body keeps trying to start then stopping. Hoping that baby stays in atleast a few more weeks but I have a feeling she will be early !