How Accurate Are Estimated Fetal Weights From Ultrasounds

10 Replies
WP - October 11

Does anyone know this? I just had a post-dates u/s done today and it's estimating the baby at 9 - 9.2lbs!!!! I'm freaking out! My induction isn't until next Wed, which means it could actually get bigger over the next week. My first was 9.4lbs and he BROKE MY TAILBONE on the way out!! It took me almost 2 months to fully recover from that. My doctor is away until Monday and I don't know what to do.


Punkin - October 11

My doctor wouldn't even guess on a weight. He said they did a study on the day before the baby was born: They had the doctors feel and guess a weight, they sent the women to ultrasound for measurements to guess a weight, and then the expectant moms took a guess, and he said BY FAR the moms were closer!


alirenee86 - October 11

Yikes. Well, if your first was that big, it seems very possible that's probably close to correct, I would think. I just had that done on Tuesday, an ultra-sound where they guessed the weight for the first time and I was happy to have an idea, though I'm only 35 weeks so he's only 4.14 ounces so far, or so they said. I can't believe your first broke your tailbone. That sounds horrible. Don't stress. I'm sure it will be easier for you the second time around...


January - October 11

They say u/s weight estimates can be off by a pound either way.


Jilloh - October 11

with my son my doctor gave a pretty accurate guess on weight saying anywhere between 7, 12 and 8, 8 (he was 8, 4). However this is not always the case. Sis in law had a baby 10 weeks ago she was told her baby was going to be 6-7 pounds it ended up at 8, 15. Another sis in law just had a baby yesterday they prepared her for a 4 1/2 - 5 pound baby. She got a 6, 7 baby. So they are wrong and they are right.


micorazon - October 11

Im so glad you posted this...I have been stressed all day becaues my doctor made a comment that our baby was "small" stating that she thinks the baby is about 4-4.5lbs (I will be 37 weeks tomorrow). I am scheduled for an ultrasound next week but I am so worried that something is wrong...4.5 lbs sounds very small for this point in the pregnancy. Im hoping that she is off by about a pound and that by the time I deliver he is over 6lbs.


qdogs_navywife3 - October 11

When they gave me my estimates at 35 weeks my baby was only 4 1/2 lbs. At 37 weeks they said she was 6lbs 12ozs. She was born that day and she weighed 6lbs 6ozs. I hope that helps.


qdogs_navywife3 - October 11

Oh and they got those estimates from u/s


corbin289 - October 11

I had an ultra sound on my due date and they told me he was 10.5lbs I FREAKED. 13 days later he was 9lbs so dont freak to bad. My midwife said they can be up to 2lbs off.


WP - October 12

Wheeee-eeww! Glad to know that it's not absolutely accurate. I'm mentally preparing myself for the worst, but I guess there's a glimmer of hope. Still, I would LOVE it if my doc phoned me today to tell me to come in for a c-sec early next week, but I'm not holding my breath.


Pearl - October 12

I got my baby's weight estimate on Monday. The doctor said that babies (of course) vary in size, but he was estimating mine at between 6 and 6.5 pounds at 36 weeks. My first was 7 pounds 6 ounces (born at 40 weeks) and I was told she was over 8 pounds and my second was 5 pounds 9 ounces (born at 37 weeks). I was told he was a little small but "average". Hope that helps a little.



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