Placenta question & Cervix question!

[akblaze]

We had our anatomy scan today, yay!!!
Baby boy is perfect and just gorgeous!
But I have two questions!! (midwife appt isn't until friday!)

at our 17 week private gender scan the tech said I had an anterior placenta, which I knew because I hadn't felt baby move much at all, just very faint really low down and the week before my midwife said (after listening to the hb via doppler) that I probably had an anterior placenta because she heard a lot of noise besides the hb.
However, today at my 20 week scan the tech said it's posterior. I commented how that's weird because at 17 weeks the tech said it was anterior.. she just said the tech must have been wrong and at least she was right about the sex of the baby! However, I'm pretty darn sure it was anterior. Can it go from anterior to posterior in 3 weeks?? I know as the uterus grows the placenta moves but that seems awfully quick to go from ant. to post. This one is mainly just curiosity!

Second question...
My cervix measured 3cm (abdominal ultrasound) and I have a history of PTL. At 32 weeks I found out I was 5cm dilated, I had no idea.. I had just had so many braxton hicks starting in first trimester so after so many false calls to the OB I started to ignore them and next thing I knew I was in PTL.. I'm currently on weekly progesterone injections and I've been having contractions exactly like last pregnancy.
is 3cm at 20 weeks normal? I'm sure it is, and I'm sure I'm worried about nothing but I just want to make it to full term... I DON'T want another NICU stay!!!

Thanks for your input ladies!

 

[sharan]

I've got an anterior placenta and had the same in all my pregnancies. I was told that it isn't possible for the placenta to move to a posterior position after about 14-15 weeks. It may move up as the uterus grows however.

In regards to the cervix;taking measurements using a trans abdominal scan is highly inaccurate. It has to be done internally (transvaginally). All my cervix length scans were done this way. So if it cervix has been measured as 3cm it could in fact be longer in reality.

Here in the UK they don't start worrying about the cervix until it is under 2.5cm. My cervix last week was measuring exactly 2.5cm and I was called back yesterday for it to be measured again, where it measured 2.28cm with top 1cm funnelling (opening up). I'm now in currently in triage awaiting a space in theatre to have a cervical stitch inserted.

If you are concerned about your cervix and your previous ptl then I would insist on having an internal scan being done to measure the cervix more accurately.