Ultrasound - measuring 1 week behind

gerbies

I am 7 wks, 2 days today (based on LMP) and I went in for my first ultrasound.  The baby is measure at 1 week behind, or 6 weeks.  Though I didn't do IVF or IUI, I feel like I knew when I ovulated.  I track temperatures and took OPKs and typically you ovulate 1-3 days after your positive OPK.  I'm worried.  I mean, they told me that the ultrasound can have an error range of a few days and I could have ovulated later or implanted later.

The positives are that the baby had a very strong heartbeat and every else looked good (yolk sac, placenta or whatever else they can see).  I also am having strong symptoms (morning sickness, fatigue), so my hormones are on par.

I go back in 2 weeks for another ultrasound to see how much the baby has grown.  Anyone else have this happen and result in a positive outcome?  For those of you who didn't have a positive outcome, were there any other indicators other than being 1 week behind?

tpete12

I lost a baby in June. I was 22 weeks along, but the baby only measured 15 weeks. My placenta did not grow, therefore the baby could not grow. I honestly wouldn't be worried about being a week behind. Your body may have just tricked you this time. Good luck at your next ultrasound!!

AnnikaD20

Ultrasound, while probably the most accurate dating method, can still be off by more than a couple days. At different points I had my baby measure both 10 days behind and 5  days ahead during my last pregnancy. My OB wouldn't adjust my official due date unless the ultrasound placed my baby more than 2 weeks off from my original EDD.

Ultrasound works by measuring the "echos" of reflected sound waves, carefully timed, as they bounce off your various squishy lumpy internal bits. Even with careful image processing, there's distortion. The exact length measurements aren't as important as things like seeing the heartbeat and all of the features developing properly.

katie0919

If you temped then you would *know* when you ovulated based off your temp spike (you wouldn't be saying that you *think* you O'd 1-3 days after a pos OPK). Also, you can have more than one LH surge in a month, so unless you were religiously temping and fertility friend predicted an O date based off those temps, OPk's and secondary signs, I wouldn't count on OPK's alone. With my son I wasn't temping or doing OPK's and he was 6 days behind what I *thought* was my due date based on LMP.

What cycle day do you think you ovulated? For example, according to my LMP, I should be 7 weeks today. But, I ovulated on cycle day 16, therefore my due date is pushed back two days, so I'm 6w 5d. I temped and did OPK's, I also had a sonogram yesterday and was measuring exactly what I thought based on my O date.

gerbies

Great feedback! My LMP started on 12/29, which would put me at 7 weeks 2 days and a due date of 10/5.  Based on OPKs, temping and checking other fertility signs (CM), Fertility Friend noted my OV date could have been either 1/14 or 1/16 (two spikes).  I think it might have been 1/16.  Using an on-line calculator using ovulation date, that changes my due date to 10/9.  That could explain 4 days difference.  Perhaps the error range with ultrasound measurements could account for the remaining 3-4 days?

tashaandmatt

I wouldn't worry about a week. They can be wrong. My daughter's EDD was March 20th (calculated by u/s) but I knew for a fact the day I concieved her put her at being due on April 7th.

gerbies

Thank you. I guess all I can do is wait 2weeks until the next ultrasound...

MamaOwl15

I thought I was a week ahead of what I am because of my last LMP. I'm guessing I must've ovulated on or about CD 21, which would be atypically late for me.

I'm 7w 1d, and I've had 2 ultrasounds. Baby has grown and developed a heartbeat on schedule . . . I wouldn't worry about 1 week as long as everything is measuring on track.