Verified answer

it's just how the baby is growing. I was measured in one ultrasound, and my due date was pushed back. Next ultrasound, it was moved forward. It jumped back and forth through a one month difference, but my doctor continued to base it on my lmp. My son was born 2 days after my due date. Due dates just mean the baby will come around that time, don't worry about the difference of a week. The baby will come when he/she is ready. Congrats!

Could have been either. It's hard to tell. When I went for my first appointment, and ultrasound, I thought I was 8 weeks. It turns out I was 6 weeks 1 day. I had my son at 40w3d, so my due date was pretty accurate.

well if your cycles are off, then that would effect ovulation and your due date