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Readers Respond: How big was your baby supposed to be via ultrasound?

Responses: 31


Updated May 11, 2009

Ultrasounds are a very common test in pregnancy. They can give us a lot of information about how a baby is doing and what complications might befall a pregnancy. However, ultrasound does have its limits. One such limit is the inability to tell the size of the baby accurately. Despite this fact, many practitioners are still trying. This can lead to many complications including induction of labor for a big baby, cesarean section and other issues. Some estimates are that ultrasound can be off by more than a pound in either direction. Did you have an ultrasound for fetal weight? How did that knowledge affect you?

This is kinda sad...

I'm reading everyone's posts and I'm saddened by how many say "The doctor was afraid the baby wouldn't fit so I had a C-Section" Ladies, women can give birth to large children. My husband's great grandmother gave birth to a 13 pound child at 44 weeks. Vaginally. There is RARELY such thing as "too big for the birth canal." My 100 pound cousin gave birth to two over 9 pound babies naturally..and her mother gave birth to 8 children ranging from 7 pounds to almost 11 pounds all vaginally, at home with a midwife.
—Guest Sara

Not Even Close--during labor!

I had an ultrasound while I was PUSHING in labor because my baby wasn't moving down the birth canal and the OB wanted to see what was going on. At that point he said my baby was around 7 1/2 pounds. When my son was born 1 hour later....he was only 5 lbs, 15 oz! Ultrasounds have great benefits, but accurate weight is NOT one of them.
—Guest TanyaA

Nearly right with me

I was sent for an ultrasound at 38 weeks with my first because my midwife thought my son may have been breach and my partner had been joking that i would be having a 9lbs baby at least knowing my luck so I asked if she could tell the size, she checked and he was measuring well above the 91st centile so she sent me to a consultant. He sent me in to be induced at 39.6 weeks but then changed his mind because my son wasn't engaged, he decided to send me for another ultrasound to ask for an estimated weight which they said would be 9lbs 14oz. He convinced me that it would be best to go for a c section (which I really didn't want). Jack was born by c section 4 days later weighing 10lbs 4oz. Although I do hate the fact that I didn't go into labour I don't regret having a c section as it's better to be safe than sorry. I'm now 30 weeks pregnant with my second and I'm having an ultrasound at 36 weeks to estimate her weight, hopefully I'll be able to have this one naturally. :)
—Guest Sam

Scare tactics!

Got in literal screaming match with obgyn who was fired one month after I delivered and filed complaint she wanted cut me open for 10.5 in 2nd baby, I didn't let her, but agreed to induction at 37 weeks baby was 8ibs 13oz, 6oz bigger than my first baby. Found out she was on vacation 2 days later and I was the 30th unnecessary c-section within the last 6 mnths. Wow it's amazing the info lawyers an get. I go to the same practice still because they ALL know and are afraid of me, they haven't dropped me yet!
—Guest Big baby mama

Scare tactics

I am by my own estimate about 35 weeks pregnant but the doc insists that I'm really only 34 weeks and some days and that my baby is growing about 2 weeks ahead of schedule. He said the baby was big and sent me for an ultra sound. The tech said he was close to six pounds already and went on to tell me if he was a ten pounder by labor day that I would have to have a c-section. I asked...what happened before c sections when people had big babies? I don't think I need to jump into having a c-section just because he might be a little big. She said "They died...that's what happened to them." I'm due soon and I'm interested to see how big he will actually be and I'm sticking to my guns and having my natural vaginal birth!
—Guest feathers

big babies

I went full tern with my son, the docs told me he would be about 8 pounds a week before I had him. He turned out to be 11 pounds. This is proof they can't always tell!
—Guest sryan

way off

Doctors told me at 35 wks that my baby was around 4 pounds and would probably need medical attention 4 days later I give birth naturally to a 5lb 10oz healthy baby girl
—Guest stacey

historically high on both

First time I was told I would have a 10lber -- he was 8lbs, 4oz. Second time, a 37w u/s said he was 8lbs, 13 oz, when he was born 2 weeks later he was 8lbs, 14oz. It really is just another tool used to scare mom's into a section. There is no such thing as a "too big" baby UNTIL you have had the trial of labor. Jumping to sections is one of the reasons I had to leave the med mal defense side of things -- I couldn't in good faith defend doctors who where lying to patients to make their job easier.
—Guest wmbk

Induced both times

I was induced both times and I had a 9.8 and 9.1 pound baby. First one I had an episiotomy and second one I didn't need one. Third one on the way and will be induced next week.
—Guest Seena

It's only an estimate

I am a sonographer and am familair with this weight issue. The most accurate measurement for ultrasound happen in the first trimester - and even then can be up to a week off. As the pregnancy progresses, the measurements are less accurate with up to a three week range of error...or 20% in weight-which can equal up to a lb, plus or minus. It may be 2 oz-it may be 7oz or it may be the full pound. Ultrasound is a tool and should not be used as the only means of determining a pregnancy's outcome. I will say that these 2 to 3 lb differences are unacceptable. I would have been fired if I was consistanly that inaccurate.
—Guest claudia

5 pounds yeah right !!

I was told I'd have a small baby with my daughter. I excepted that she was going to be small and got small clothes. I had her by c-section due to being breech. She was born 7lbs 15 oz, nice size baby and was 53 cm long. It just proves how wrong they were! I am now 16 weeks pregnant with my second baby [ its been almost 9 yrs ].
—Guest tannii

Baby Size during ultrasound

The nurses all told me to expect an 8lb baby- just like with my first son- who we were blessed to keep- she was born one day difference gestation at 38 weeks and 2 days and was 19inches long- only 6lbs and 9ozs.. She almost made it!! So tiny- and I just knew my son was tiny!!
—Guest Sunshine Allen

Big Baby

I was told my baby was weighing about 8lb so I was induced at 38 weeks turned out she was 10lb 5oz. I had a 3rd degree tear was only six weeks ago waiting to go back to the hospital for a check up next week to see what happened.
—Guest mazza

advice taken

I have multiple reasons for the doctors in the semi small town hospital to try to get a c-section scheduled, but I won't agree - I am on 6th baby, 4th baby was c-section, but 5th was VBAC. I am overdue, with too much water and a baby estimated to be 10 lbs. They want to induce after the weekend which I got new of over the phone - I refused for the induction is risky to me and the baby for uterine rupture. I think the birth weight estimate is not enough for me to take so much risk and I am disappointed that they keep pushing for this. I want to have the baby natural on the baby's schedule, big or not, we will be just fine, I think the doctors like to control a little too much, ya know? Just let it happen...
—Guest RLK

Ultrasound was way off!

I had a boy just 2 weeks ago and when i was 35 weeks they told me he was 6 pounds and would weigh about 8 pounds at birth. He was only 5 pounds 9 ounces.
—Guest mommy2
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