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I personally think baby is just measuring ahead...the earlier ultrasounds are more accurate from what I have heard.

I'm 21 weeks now (by lmp), and my due date has switched back and forth as well, and my ob isn't concerned at all. She says that as long as it's within a week-ish it's not something to worry about, due dates are really just estimates. By lmp and my u/s scan at 12 weeks, my due date is 2/6. By scans at 8, 9, 16, and 21 weeks, I'm measuring closer to 2/12. I'm pretty sure I ovulated/conceived late as well! I keep worrying about this lo's growth, but my ob keeps reassuring me.

eta fwiw, my ob is keeping my edd as my lmp date, 2/6, though maybe after my anatomy scan at 21 weeks she'll change it again...who knows! the exact size is so hard to measure anyway--on the day lo1 was induced at 37 weeks, she measured 7lbs 1 oz and when she was born she actually weighed 5 lbs 13 oz--big difference! One of the drs told me that the u/s scans are great for seeing extremes, but less accurate within the average range. I think as long as they see growth at a rate they expect it's fine!

Based on what my doctor has been telling me, I'd also guess you are measuring ahead. I measured 5 days small at my first ultrasound so my 10/31 due date got moved to 11/5. My subsequent ultrasounds have put me back on track for an 10/31 due date but my doctor's office says the only reliable measurement is that first one so my 11/5 due date is standing firm. They claim that I must have been wrong with my ovulation date but I also used BBT charting and OPK's and if their dates were correct, I would have gotten my positive HPT something like 5 days after ovulation. I'm not putting a lot of stock in my due date. We'll see what happens.

Interesting. My dr/midwife always went by that first scan @ 8 weeks (which was the same as my LMP.

With DS1, I measured right on target the entire pregnancy (although I didn't have an ultrasound after 20 weeks).

With DS2, they never moved by due date, but baby measured ahead the entire pregnancy. I had so many ultrasounds (high risk) and he was always measuring at least a week or two ahead.

DS1 was born at 38w6d. 8lbs 3oz
DS2 was born at 38w4d. 9lbs 11oz

I had no idea you were pregnant--CONGRATS!

Now back to regularly scheduled programming...

The later you get in pregnancy the less accurate ultrasound measurements are for dating (i.e. our babies start to grow at their own pace vs a standard one), and there is a degree of imperfection in ultrasound measuring. I say this as someone who has done a fair number of these on patients. So maybe the repeated ultrasounds are just getting slightly less accurate. Usually your due date by ultrasound needs to be pretty off to adjust your due date overall. Personally I would go with your earliest ultrasound that sounded like it matched your O date, but obviously your docs know your situation the best. Your baby is just a little ahead of the curve, I wouldn't stress about it, medicine is an art