If your early u/s dates didn't agree with your chart dates...

flyer23 · June 2009

...how far off was the ultrasound?

My chart says I'm 6w5d, but my ultrasound today says I'm 6w3d. The tech didn't sound very concerned, but she also didn't know that I was charting and pretty darn sure of my O date. It is *possible* that I O'd two days later than I thought. (I had a huge temp dip at 2 DPO that I thought was a fallback rise, but it's entirely possible that my high temp at 1 DPO was actually an outlier, and my "true" O date was what I thought was 2 DPO.) But having had a miscarriage last time around and tested with low progesterone this time around, of course I'm nervous that measuring behind is "bad."

The heartbeat was 125 bpm and the tech said that was good for this point in time.

Grrrrrr... one of these days I will stop overanalyzing every. little. thing.

nowmrsbinkc · June 2009

My doctor didn't seem to care at all that I knew what day I ovulated. According to that my due date should be January 13. The nurse at the dr.'s office told me January 10 (based on some table she was using). The dr. told me a week later that the baby was measuring at 7w6d when we thought it was 8w2d and then told me my due date was January 9 (still haven't figured out how it was measuring smaller and they moved the due date UP a day, but whatever). Basically, I decided I'm going with January 10 for my due date because it is fun (1-10-10) and easy to remember. I won't really consider myself overdue though until I get past January 13.

ETA: To answer your question...the baby was measuring 2 days behind what the nurse thought it was, but one day ahead of what I thought it was!

OliveBerry · June 2009

Mine is off by a week. Drs don't generally seem to be concerned unless it is a couple of weeks. I think most of us are off by a few days at least.

amoureux · June 2009

You are not measuring behind at all. The margin of error on an u/s is +/- a week or more depending on the machine.

The hb is great. Try to relax.

When you are measuring a couple weeks different, then it is time to worry if you are sure of when ovulation occurs.

Blackvelvet · June 2009

I was charting at my 12 week U/S I only measured at 10 weeks. They didn't change my due date though becasue I had a diary of our possible days and it wasn't possible. By 20 weeks I was measureing 20 weeks. I'm not sure if you can really worry at all about 2 days though it seems small weeks are way more important

MrsTiu2006 · June 2009

At my first appointment the baby was measuring 2 days ahead of what I thought. The Dr. decided to go by the day of my last period anyways (even though I had been charting). However, the u/s tech said she can be off 3 days in either direction.

Valerie Padron · June 2009

what difference does it make? it's not like it's off by weeks, KWIM? As you know, only 5% of babies are actually born on their due date.

Take a deep breath, put the chart away and try to stop freaking out about measurements. They are based on means and averages, no two babies are alike.

Sticky vibes to ya!

ibis · June 2009

I measured three days ahead of when I thought I O'd. There is a small margin of error both with charting and with early u/s.

SaranJonathan · June 2009

My doctor says as long as things are within 6 days he is good with it

Anna&Matt · June 2009

as long as it's within 5 days or so my doctor isn't worried.?

KaseyBrent · June 2009

My Dr. Said it is a hit or miss thing, and that 40 weeks is a typical gestitation period, but give or take 2 weeks. So I would not worry at all about a "specific date" as most women do not deliver on their actual due date.

easjer05 · June 2009

I measured 4 days behind my O date at the first u/s (6w4d, measured 6w0d). I left things as they are for many reasons. At the emergency u/s a week ago (9w0d by ovulation), I measured 8w3d (exactly two weeks and three days after the u/s measured me 6w0d).

A couple of things to note -

1. While we are used to pinpointing the day of ovulation, scientifically speaking, it's a method that is only accurate to within +/- 3 days. We can't pinpoint ovulation with precision accuracy short of drugs and u/s monitoring.

2. U/s is considered extremely accurate, but it's worth noting that the machines have a margin of error of +/- 3-7 days, depending on the resolution of the machine (and the accuracy/experience of the technician). Additionally, it's worth noting that while there is a certain level of growth expected, babies can and will grow in spurts and at their own rate. Doctors usually won't change an edd unless there is over a week's difference.

FWIW, I was a little freaked out by the measuring behind. But then I remembered that one of my friends measured a full week behind her chart date and they moved her edd. She was really concerned. When she had another u/s, she'd moved up two days ahead of her new edd and they changed it again. And then at her NT scan, she measured a 6 days ahead of her new edd - back in line with her original chart dates, which is her edd once again.

Another friend of mine was on a fully medicated IUI cycle with u/s monitor and trigger, and she measured 3 days behind her ovulation date. They changed her edd based on that and when she went in for her NT scan this week at 11w5d, she measured 12w3d.

The EDD is just a guess (hence 'estimated' due date) - babies will come when they want. And while it may seem a bit concerning to measure off of where you expect, there are a lot of reasons it can happen. The important thing is a good fetal heartrate, which you have. Relax and try to enjoy.

flyer23 · June 2009

Thanks everyone...

FWIW, I'm not at all concerned about the EDD being "correct." I'm well aware that babies don't come on their due date... DD was born two weeks late Smile And actually, in that case, she measured 4 days behind at her first u/s and my doctor did not change my EDD, even though I was almost positive I had O'd after day 14. (I wasn't charting, but I've always had long cycles. The EDD I ended up with was based solely on LMP, i.e. a "normal" 28 day cycle.) I regretted not pushing to stick with the EDD given by u/s at the end, when I had to be induced for postdates... so this time around, I'm perfectly happy to get two extra days at the end to let the baby bake.

My concern is *solely* that the baby is not growing properly right now. But it helps to hear that u/s can be off, and charts can be off too, and that the h/b is the most important thing.

Thanks... I WILL try to relax, promise.

emma7875 · June 2009

Mine was off by two weeks so when I thought I was 7 weeks the doc told me that I was only 5. They said it was probably because I didnt ovulate till later than I thought. Nothing wrong though. Heard the HB last week and it was at 157bpm and got pics so don't be too worried about it. They also told me that my progesterone was "on the low side of normal' It was at 11 but they keep telling me just to stay relaxed and try not to overdo it. GL

NCMichelle · June 2009

Yep, I'm a week and 1 day earlier than I thought I was... relax. It's fine!

LORIL1109 · June 2009

this all confuses me.......

if going by LMP, my due date would be 1/26 and I'd be 7w4d

however, i KNOW when i ovulated b/c i was being monitored w/ scans and bloodwork.....so, according to that date, which was a late ovulation.... my edd is 02/01/09 and I'm 6w5d.....and that's how I measured at my US this past week....

however, people are telling me that once I'm released from the RE and go to the regular OB that they won't use the ovulation date at all and use my LMP EDD...does that make sense?? even though I'm measuring exactly according to date of ovulation???

ChicNotGeek · June 2009

At my first visit, I thought I was going in at 7 weeks, but the ultrasound said that I was 10 weeks+ ... the funny thing is that I have no recollection of having sex at the time that I apparently conceived. So I just say that I was pregnant before I even knew that we did it!

ChicNotGeek · June 2009

ANd even though I was three weeks off, the heartbeat was good, the nurse/doctor said that the ultrasound looked perfect, and everything was OK. The only result was that I had to go in the very next week for my CVS test, (since there's only a window of 10 - 12 weeks to do it). ANd I just got the results, and that was normal, too.

So, my advice/recommendation, don't stress out over 2 days.

flyer23 · June 2009

LORIL1109:

this all confuses me.......

if going by LMP, my due date would be 1/26 and I'd be 7w4d

however, i KNOW when i ovulated b/c i was being monitored w/ scans and bloodwork.....so, according to that date, which was a late ovulation.... my edd is 02/01/09 and I'm 6w5d.....and that's how I measured at my US this past week....

however, people are telling me that once I'm released from the RE and go to the regular OB that they won't use the ovulation date at all and use my LMP EDD...does that make sense?? even though I'm measuring exactly according to date of ovulation???

Talk to your OB about it. If you know your ovulation date, and it matches up with the u/s, there is no reason to use your LMP date.

FWIW, my LMP was 4/15, which gives me an EDD of 1/20 (and means I measured almost two full weeks behind), but I know that I O'd later, due to my chart. I haven't talked to my midwife about this specifically yet (my first appt is on Monday), but her nurse has given me every indication that they won't go with the 1/20 EDD because I know I O'd late and now the u/s has backed that up.

They just use LMP for people who don't know when they O'd, like me during my pregnancy with DD! Smile

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