Could my due date be off based on the the size of the baby in the gestational sac?

Chandelle - posted on 11/10/2011 ( 23 moms have responded )

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I'm 30 weeks, and apparently my baby is big and my gestational sac is measuring big. I am also having symptoms a few weeks ahead, for one my baby has dropped already and this is baby #2. I was wondering if my due date could be off considering it was with my first and we don't know exactly my date of conception because I was on birth control. We have an idea of when it happened and my last ultra sound was at 18 weeks

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Jodi - posted on 11/10/2011

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So you were measuring big at 18 weeks too? And now you are measuring bigger?

Basically, all babies pretty much grow at the same rate until about 20 weeks (or thereabouts), so it is much easier to gauge a due date from those ultrasounds, so there is a possibility that your 18 week one is the most accurate. After 20 weeks, each baby grows at its individual rate, and some fall within the normal curve, while others will start to measure small or large for their gestational age. It may be that the original dates were out by a week or two, but it is highly unlikely to be more than that (which is why they call 39-41 weeks full term, not just 40 weeks) if you had early ultrasounds.

It may just be that your baby is big. If you have gestational diabetes, it can result in a bigger baby, but the other thing to remember is the size of yourself, the father and other family members. If one of you comes from a family of large babies, then chances are, that's what your baby will be too.

Jodi - posted on 11/10/2011

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It could be, but the later the ultrasound, the less accurate it is. Early ultrasounds are more likely to be more accurate. Did you have an ultrasound before your 18 week one to have it dated?



I had the opposite problem, with my daughter measuring too small for my dates, but because I had a 10 week ultrasound to date the pregnancy, the measurements at that age are by far the more accurate, so my doctor stuck with the original due date. She came near her original due date, and was just a very small baby, but full term.

Kellie - posted on 11/10/2011

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Yep it could absolutely be off. ultrasounds are never 100% on the money in such things due to all the variables.

Ashley - posted on 11/11/2011

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both my boys measured big for the appointments, with my first he was 4 days late and my second which I dropped a full month before my due date and had contractions for 3 weeks was 2 days late. 8lbs 10oz and 10 lbs 2oz respectively. My 3rd which I am currently pregnant with at 32 weeks is measuring 3 weeks ahead of schedule and I do not have gestational diabetes which I was tested for twice.
Ultrasounds are bad predictors and most drs shouldn't give thier opinions b/c they are wrong too. Baby will come when he/she is ready and if that is early it will be a surprise and if he/she is late than you will be waiting lol.

Good Luck with it all!

Jodi - posted on 11/10/2011

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Well, if it is any consolation, Chandelle, ultrasounds are also notoriously inaccurate.



At about 5 months, they were freaking out because my baby was below the charts, and they were telling me she was WAY too small and then 6 weeks before I had her they told me she measured at 5lb something (can't recall now), and would probably be 7lb full term, and she ended up born full term at only 5lb 2oz, so they were totally off.

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Lisa - posted on 11/20/2011

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Make sure your doctor checks for pelvic disproportion. That the size of your baby's widest part their shoulders will pass through your pelvis.

Aniesha - posted on 11/19/2011

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It could be, or there could be other reason. You could have an extra big baby, or you could have a lot of amniotic fluid (polyhydramnios). I had that problem with my first baby, and same with this one. However, I'm absolutely certain of my dates, so I know that's not it. Are they giving you an ultrasound to check why you're measuring big?

Ez - posted on 11/19/2011

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The sharp pain in the vagina is a sign of your cervix ripening and possibly dilating, but they can happen for many weeks before birth. If your contractions went away with rest, they are generally nothing to worry about. Just take it as a sign to rest more and not overdo it.

As for the size issue, don't worry about it. My daughter measured WAY off the charts from about 28 weeks onwards. My fundal height was 49 at 37 weeks. I had no GD, upper range of normal amount of fluid, but a strong family history of big babies. After several growth scans she was predicted to be 11lbs+. She came out 9lb 6oz, 22in.

Chandelle - posted on 11/19/2011

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Ok now I've been having contractions that went on for two hours they would get brought on by walking by doing anything, they eventually went away when I relaxed and didn't get anymore painful. But now I'm having pains in y cervix like a sharp shooting. 31 weeks should I be worried

Chandelle - posted on 11/12/2011

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Lol I'm noticing a due date just doesn't mean anything, and I feel like the doctors just try and scare you sometimes

Nerissa - posted on 11/12/2011

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My daughter was measuring small and was born at 7lb 4oz. My sister just had a daughter and was measuring big (41 weeks at 37 weeks) and was born 7lb 4oz. She had also had an u/s at 30 weeks that showed the baby as big. Obviously you have to take these measurements with a grain of salt!

Sally - posted on 11/11/2011

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A due date is a guess based on an average cycle and an average gestation. If you didn't know your start date, your due date is even more of a guess. Ultrasounds are a terrible judge of baby size and an educated guess (based on averages) of gestational age. The further your pregnancy, the less accurate it is.
Based on a 30 week ultrasound, my first was "supposed" to be 8-10 lbs and three weeks early. She was forced out a week "late" at 6' 10". With my second I didn't start dr visits until about 25 weeks. My uterus measured a month past dates. The ultrasound said everything was fine. She came out even later and tinier than her sister.
Your body and your baby know how big it should be and when it should come out. Try to relax and trust them.

Chandelle - posted on 11/11/2011

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Well he is definately settled in my pubic bone, I'm getting sharp shooting pains in my cervix area as of today lol. Any ideas on how to sooth that lol.

Chandelle - posted on 11/11/2011

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I just had it done today, I'm waiting on the results I ended up taking it kinda late our place has weird hours.

Lisa - posted on 11/11/2011

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Make sure they test for gestational diabetes if there is a big discrepancy and you are large for dates.

Kelina - posted on 11/11/2011

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My first dropped 3 days before I delivered but my second dropped at 30 weeks! also, go with the due date from the earlier ultrasound. I think it's ridiculous that they will change your due date with a later ultrasound since it's waaaaaay more unpredictable. Your body knows whats happening and will tell you when it's time no matter what your doctor thinks.



Edit to add: My widwives told me that since my second was a daughter she would probably be smaller than my son, closer to 7 lbs. She was bigger. Also my ultrasound told me my due date wsa Dec 15th, and then moved it to the 18th or soemthing but I just laughed and had said from the beginning that she would come around my birthday. she was born two days before!

Sarah - posted on 11/11/2011

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Hi, we and all babies are different. Due dates are just silly, we should be given a window of time for expectancy....we hold out for that date...but we're all different depending on baby size. And big babies don't particularly mean an earlier delivery and an incorrect date. Both my babies measured a few weeks ahead in size....so I had my hopes up they'd be early but instead were 2 weeks late and 9lbs/9lbs2oz! So long as you're being monitored well and all is healthy....it doesn't matter....your midwife will be checking you very regularly in the the last month and will know if you need to deliver earlier. All the best :)

Lisa - posted on 11/11/2011

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I measured weeks ahead for my dates. My doctor did not take this seriously enough. Ultrasounds have up to a 20% margin of error in calculating weights of bigger babies (over 9lbs). My doctor told me she figured our son would be close to 10lbs. Imagine our surprise when he was 12lbs. It was a horrible vaginal delivery. Had she paid more attention to my fundal height she would have seen this. I should have had a c-section. I hope you either have an obstetrician or will consult with one prior to your delivery if you continue to be large for dates.

Chandelle - posted on 11/10/2011

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Lol they are def little surprises through and through. Very helpful answers though I'm glad I signed up!

Carly - posted on 11/10/2011

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I too breed big babies its a cross some of us have to bear :o) haha mine was predicted to be around 8 lb and ummmmm came out 9lb 12oz... And this time too I am measuring almost 3 weeks bigger than I need to be but I know my dates were absolutely correct - on the upside I get to have a c-section with this one so its not coming out the business end so it can be 15 lb for all I care. If you are sure of your dates I would take it as gospel - oh and I am 33 weeks now and mine had dropped too...

Sorry I wasnt much help but hopefulyl makes you feel a little better - on the up side big babies sleep better at night :o)

Chandelle - posted on 11/10/2011

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Lol, no gestastion diabetes, and I am small, all my moms babies are small my actual belly is measuring small, my husbands mom had average babies and my son was 6lbs when he was born. Makes me curious what this little fella is gonna come out like.

Chandelle - posted on 11/10/2011

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I had an ultra sound at 7 weeks but my due date moved up with the 18 week.

Sharlene - posted on 11/10/2011

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Hi , I had 4 childre after my first child the other 3 turned at 20/24 weeks I would'nt be that concern it's probably just a very big baby plus if it was that much of a concern your O/B would requir you to do more blood test and ultra sounds and put you in hospital .All the best with the pregnacy ,cheers

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