Ultrasound measurements

Vivi20 · June 2016

So I had my first ultrasound yesterday, and praise God all looked well. We saw our beautiful, sweet baby and a good heartbeat. I'm 9 weeks and 4 days today, but the doctor said the baby is measuring at about 8 weeks and however many days (can't remember now). I'm positive of when my last period was, so that's not a question. I asked my doctor, then, how far along am I if the baby is measuring a little less? He said I'm still 9 weeks and we'll still keep my same due date of January 20th.
So, has anyone else measured a little behind? I guess it makes sense that not all fetuses grow at the same rate and are the same size...my dd is nearly 3 and is a tiny thing, she still fits in 24 month. And I'm small, too. So I guess my fetus is just petite also?

ThePax89 · June 2016

I think because there is a strong heartbeat, it isn't as concerning. What was the heart rate? Was the measurement off by less than 7 days?

TinaBelcher · June 2016

Measurements are typically accurate to +/- 5 days, according to my RE, so I wouldn't worry much! Just today one of my babies was moving around so much she took 3 measurements in a row and they varied by about 4 days!

Vivi20 · June 2016

Good heartbeat, around 140. Yes, it was less than 7 days.

Vivi20 · June 2016

Thank you @TinaBelcher. It's been worrying me just a bit, but my doctor had no concern with it and said all looked well. Not even born yet and already causing mommy stress!

sarahmsoda · June 2016

Measuring from your last period has quite a few days of error because you may have ovulated later than "average". I always ovulate late so mine was a few days behind as well when based on lmp but because I knew when I ovulated I wasn't concerned

Vivi20 · June 2016

See, and I don't know when I ovulated. I got pregnant after my first real period after having an iud removed. Prior to that I hadn't had a period in over two years, so I don't know how long my cycles are anymore.

ElleMF728 · June 2016

jlea05 said:

See, and I don't know when I ovulated. I got pregnant after my first real period after having an iud removed. Prior to that I hadn't had a period in over two years, so I don't know how long my cycles are anymore.

LMP is not accurate because it assumes a perfect 28 day cycle with ovulation occurring on the 14th day. Its pretty rare that those perfect circumstances actually happen. Dating ultrasounds are the most accurate way to determine gestational age during the first trimester since all babies tend to develop at the same rate at this point.

Its likely you ovulated a bit later in your cycle but a lot of OBs will continue to go off of your LMP unless you are over 5 days off on your EDD. During my first pregnancy I ovulated extremely late so my LMP due date was off by about 2 weeks. I had a healthy baby and healthy pregnancy.

LoneStar21416 · June 2016

If you don't know when you ovulated, I wouldn't even give it a second thought. And even if you did, I don't think that's a huge deal. Like others have said, there is a margin of error based on positioning of the baby. I know when I ovulated, and I have a very "typical" cycle. My O date was only one day off from the typical 14 day cycle. Anyway, at my dating ultrasound baby was 5 days ahead. At my last ultrasound, baby was 2 days ahead. It can vary based on machines and positioning. My OB is not changing my due date for this very reason. I wouldn't worry!

Vivi20 · June 2016

Thank you so much ladies. I know I shouldn't worry about it, but reading your responses makes me feel better anyway.

colleenkevin · June 2016

I am really anti-induction because the stats say c-section risk increases with inductions and the 4 people I know who were induced all ended in C-sections for failure to progress. So, I just want to add that if your due date based on LMP is still a week off from where your baby is measuring at your next ultrasound and he doesn't adjust your due date, you might want to have a chat with your OB about what that means for end of pregnancy. My doc will let me go to 42 weeks per ACOG if the baby and I are both doing well, but my stepsister's doc insisted she be induced at 40 weeks 6 days bc "his patients don't go to 41+"

If her dates were off by a week he'd have been inducing at 39 weeks 6 days and that's a week of time her body wouldn't have had to get itself ready and make the induction success more likely. Just something to keep in mind.

LoneStar21416 · June 2016

@colleenkevin I agree with you. This was another reason I was glad my doctor didn't change by due date based off of ONE ultrasound at 10 weeks when I was measuring 5 days ahead when I am incredibly confident of ovulation and I have a typical cycle. I would have been annoyed if they suddenly though I was 5 days ahead and that became an issue at the end of pregnancy. That said, I feel like it really does depend on how certain a woman is about her cycle and how close they are to the "regular" cycle.

colleenkevin · June 2016

@LoneStar21416 totally agree about not jumping to change a date too quickly after just one ultrasound.

hjmorgan-2 · June 2016

My little peanut measured the same! My US was taken at 8 weeks, but they said the baby was measuring a fewdays behind. However, my doctor said that I was still considered 8 weeks and have the same due date, Jan 20th.
I'm pretty sure the baby just implanted late, when I took my first test after my
late period the line was BARELY there, and it took a few days to show up bright pink. So I'm not worrying about it.

Vivi20 · June 2016

@colleenkevin I never even thought about that! Thank you for pointing that out, because I, too, am very anti-induction. Everyone woman in my circle who had an ob-gyn (I'm not exaggerating) was induced. I don't know what it is, but it seems doctors love inducing. Several of them, too, ended up having c-sections.
@HJ.Morgan We have the same exact situation and due date! Very cool!

katesmama0706 · June 2016

My due date got moved back 10 days based on my dating ultrasound but I actually knew for a fact I had ovulated about that many days late too so I wasn't shocked when baby measured small based on LMP. Also, I'm an elective induction girl and will be induced at 39 weeks due to crazy fast labor and delivery. I wasn't comfortable starting labor at home so as long as I show a favorable cervix I'll be induced. So moving my EDD back actually pushes my induction back.
ETA: I had a super successful induction with my last baby because I ran out of amniotic fluid. Less than 5 hour labor+ delivery for a first baby but my body was more than ready. I'd been contracting before we started the pitocin and I was already almost dialated to a 4 and 90% effaced

Tahinda · June 2016

This happened to me too. My little one was measuring 5 days behind I was due in Dec and now got pushed to January but I am sure of my last cycle.

JennaLee1486 · June 2016

Ultrasounds don't measure perfectly. I was a week from my due date with my son and the ultrasound put him at 35 weeks. They're imperfect. I would look for the heartbeat and don't worry about the rest

Jennvega87 · June 2016

Based on my 1st day of my last period I'm due Jan 23 2017. Which would be 8 weeks. But when the ultra sound was done i was measuring 5 weeks 4 days. The heart beat wasn't strong. She didn't give me the hbp. I have an appt on Monday to check how everything is going.

juliehollz13 · June 2016

The day of your period means squat. You could have ovulated later than CD14 (I always ovulate around CD18-20). It's also normal for early ultrasounds to be up to 1 week off in measurements.

gonetothesea · June 2016

I had the same thing happen at my 10 week check up. I was measuring about 4 days behind, but the doctor wasn't concerned at all. I know when I ovulated, but I have longer cycles that usual, so the doctor said that might have something to do with it. The baby had a strong heartbeat, so the doctor was happy.

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