Dating the pregnancy without the Ultrasound in 1st Trisemester

[kusumat]

What are your thought on its safety?

http://www.plus-size-pregnancy.org/Prenatal%20Testing/prenataltest-ultrasoundsafety.htm

http://www.jultrasoundmed.org/cgi/content/abstract/26/3/319

[kusumat]

My period was irregular after a year of breastfeeding (I stopped in June 2007). My last period was on Sept. 21. I had pregnancy blood tests done at the doctor's lab on Oct. 31, Nov. 14, and Nov.27. First two came out negative but the last one was positive!

I heard that quantitative blood tests usually detect hCG shortly after implantation, which occur anywhere from 6 to 12 days after ovulation. Therefore, my due date should be somewhere from July 27 to Aug 12, 2008?

I will have the first appointment with OB the end of this week. I know that she probably wants me to do the ultrasound right away to get the accurate date. However, I don't feel comfortable to have ultrasound done till 2nd trisemester which the dating might be off 1 week. Therefore, I think it will reduce the 15 days gap above.

Is the due date estimated one anyway? OB will allow the delivery that falls 3 weeks before or 2 weeks after. Also, the ultrasound is not always accurate, right? Can OB figure out the due date by the blood test timing? I really concern about the safety of the early ultrasound(in 1st trisemester) and try to avoid it. Any thought? TIA!

[KrisM]

I think they're likely safe. But, I only get them if it's medically indicated. I've not had a "standard" 20w ultrasound. But, both last time and this time, I had the first trimester screening u/s and last time I had one at 34w because I was suddendly measuring 5 weeks or so bigger.

That said, I don't think having 1 20w u/s is a bad thing either, safety wise. I am glad I've not had to have weekly scans because I would be worried then.

[egoldber]

The most accurate dating is done by an ultrasound done before about 10 weeks. Up to that point, fetal development is very predictable. After that, dating my ultrasound is much less reliable.

In all of my pregnancies, I have basically known the date of conception, and all my early ultrasounds were accurate within +/- 1 day of my EDD.

[kedss]

hi-

Our Dr. is letting us wait til 22 weeks to have our ultrasound, he said the estimated delivery date won't be as accurate as it would be if we did it in the first trimester, but it would still give us an idea.

For us its a question of cost, but I would share your concerns with your doc, it is your choice. :)

[MamaMolly]

Just my BTDT...With DD I had weekly ultrasounds from 2 weeks after we replaced the embryos until the 3rd trimester when they became bi-weekly. I practically have a flip book of scans from when she was a dot on. I wasn't aware there was a safety issue involved. My OB was very careful with this pregnancy, so I can't imagine him doing anything dangerous.

That said, this is your pregnancy and your baby and you need to trust your gut instinct on testing. Ask your OB what it will hurt by waiting? Is there anything that might be wrong that they can catch this early and fix? Or would this be a procedure just to date the pregnancy?

I know they have strict time windows for some tests for the results to be accurate. Maybe that is why it is 'necessary': for future tests. Sounds to me like you need to talk to your OB about this and find out the whys and wherefores of the test and then decide if you want to go ahead. Remember, the only wrong questions are the ones you don't ask!

I recommend keeping a little notebook and jotting down any questions you might want to ask. Take it with you to the OB and that way you won't forget anything and you can also write down what they say and any instructions that they might have. I know it sounds dorky but it really really helped, and now it is fun to go back and read.

HTH, congrats and good luck!

[Rachels]

Honestly, if you're not comfortable doing it and you had a normal pregnancy and birth prior to now, I would find a provider who is on board with the idea of a ballpark timeframe. Many midwives won't start the clock after a strict due date if you're not sure when you conceived. Mainly what you want to avoid is an unnecessary (and potentially harmful) induction. You can always do NSTs at the end of your pregnancy if it wigs your providers out not to know exactly what week you're in.

[pb&j]

My pg w/ DS was high risk, and I had about 7 u/s's that I can recall. DS is now 2 and meeting all his milestones at or ahead of schedule, and is perfectly healthy.

[Marisa6826]

http://windsorpeak.com/vbulletin/showthread.php?t=245718&highlight=ultrasound


BTW, I merged your two threads together as they're basically asking the same question.

-m

[ThreeofUs]

Most of the OB's in my area are now extremely careful with ultrasounds. Most don't recommend them until much later in a pregnancy, but then most don't start a chart until 12 weeks gestation minimum.

I had one at 10 weeks to check on the pregnancy and the heart, but it was totally unnecessary. I'll never forget the sight of DS as embryo running away from the ultrasound - mostly because I found it astounding that I now knew what feeling he caused when he moved inside me. But the OB said ultrasound causes such movement in many cases.

If I were you, I'd find an OB that matched my preferences. There's bound to be one close by.

[american_mama]

I had a vaginal ultrasound at 6 weeks with this baby to date the pregnancy. They only looked for two measurements, I think, crown to rump and something else, so that part was really quick, maybe 5 minutes. Mine went a little longer mostly due to chit-chat, but it could have ended much sooner and if I had your concerns, I would say you want the quickest ultrasound possible. (BTW, I had read some blips about concerns about ultrasounds on the internet, so safety was on my mind, but I did not do any research beyond reading blips, and I decided that standard procedure was good enough for me).

I personally have highly irregular cycles, so I want a dating ultrasound for my own knowledge. That being said, I don't take a due date as golden and would strongly resist efforts for induction based on dates.

I think if you decline a dating ultrasound and are left with ambiguous due dates, you have to think about what that means to you and your provider down the line. Will your provider consciously or unconsciously think in terms of the earliest possible due date and start pressuring you for an induction soon after? If that bothers you, do you think you can resist that pressure? Can you handle this being an issue for the entire 15 day window? Are you willing to go in for more frequent appointments during that window to reassure you or your provider? After having been in due date mode for 15 days, will you or your provider being willing to wait, say, another week after the latest date for baby to arrive (which might be enitrely normal, but might feel like baby is very overdue)? If you think you or your provider will have trouble at any of those points, I personally would have the dating ultrasound to avoid the ambiguity.

I am certain that the current evidence against inductions, especially early inductions, is stronger than the current evidence against early ultrasounds, so I would make my decision now based on what I think is likely 9 months from now.

[KrisM]

I think if you decline a dating ultrasound and are left with ambiguous due dates, you have to think about what that means to you and your provider down the line. Will your provider consciously or unconsciously think in terms of the earliest possible due date and start pressuring you for an induction soon after? If that bothers you, do you think you can resist that pressure? Can you handle this being an issue for the entire 15 day window? Are you willing to go in for more frequent appointments during that window to reassure you or your provider? After having been in due date mode for 15 days, will you or your provider being willing to wait, say, another week after the latest date for baby to arrive (which might be enitrely normal, but might feel like baby is very overdue)? If you think you or your provider will have trouble at any of those points, I personally would have the dating ultrasound to avoid the ambiguity.

I am certain that the current evidence against inductions, especially early inductions, is stronger than the current evidence against early ultrasounds, so I would make my decision now based on what I think is likely 9 months from now.

I completely agree with this. As I said above, which was an answer to the u/s safety version of this post, I don't get u/s unless I think I have a good reason to. If I were in your shoes, I'd get one now when they can more accurately determine an EDD. Otherwise, you may be pushed into an induction earlier than you or the baby want.

[kusumat]

Also, I heard from somewhere that the frequent ultrasounds perhaps may increase the risk of autism. As we still don't know the cause of it, I try to avoid any possibilities if I could. Anyone else heard about this?

[SnuggleBuggles]

Conservative use of u/s doesn't worry me but it it causes you concern it can certainly be avoided.

For dating, if you have a guess then you can see if things like 1st time hb is heard, fundal height measurements...support one EDD. There are milestones that you and baby will hit and that should give a good gauge on EDD.

Accuracy of u/s dating, according to one study:
"How accurate is ultrasound at setting due dates?
A study has shown that an ultrasound isn't any more accurate than a reliable menstrual history combined with a pelvic exam by an experienced obstetrician. Researchers confirmed this by looking at pregnancies with known conception dates and comparing due dates arrived at by ultrasound measurements with dates arrived at by menstrual history and pelvic exam (4).

The fact that the old-fashioned method for dating a pregnancy does just as well as ultrasound is a vital point. While a sonogram may be useful in cases where there is uncertainty about when conception occurred, first-trimester sonograms are currently used as the ultimate standard. Your due date will often be changed if it differs from the one derived from the sonogram no matter how the date was previously determined or how sure you are of when you conceived.

Even first-trimester sonograms have a range of plus or minus five days, or a ten-day window, around the calculated date (3). The range increases to plus or minus eight days in the second trimester and plus or minus ten days for third-trimester scans. For this reason, experts say the due date should not be altered based on results from an early scan unless the calculated date differs by two weeks or more from the date determined by physical signs and symptoms and menstrual history (3)."
http://parenting.ivillage.com/pregnancy/0,,jb56,00.html

Beth

[KrisM]

Also, I heard from somewhere that the frequent ultrasounds perhaps may increase the risk of autism. As we still don't know the cause of it, I try to avoid any possibilities if I could. Anyone else heard about this?

I've heard it in the past. But what is frequent? I don't think having an u/s for dating is going to cause a problem. And, depeding on other testing you may be considering, it may be necessary.

I had the first trimester genetic screening done, which does involve an ultrasound and some blood work. This test can be done from 11w to 13w6d and the results depend upon your how far along you are. So, if you're considering this, you'll get an u/s anyway, but you'll also need to be pretty sure of the timing of it so that you aren't in the wrong window.

As I said, I avoid u/s unless they are medically indicated. If I had a good, medical reason to have weekly or bi-weekly scans, I would do it and "risk" the increased possibility of autism. You'll need to weigh the pros and cons of each choice during pregnancy and this is just one of them.

The doppler they use to listen to the heartbeat at every appointment is an u/s. Will you do those? The monitoring most hospitals will want you to do is u/s, will you do those? There is a ton to think about here!

[sidmand]

Also, I heard from somewhere that the frequent ultrasounds perhaps may increase the risk of autism. As we still don't know the cause of it, I try to avoid any possibilities if I could. Anyone else heard about this?

I was very concerned about this because DS has been diagnosed with PDD (on the autism spectrum). I was not aware when I had DS about any studies linking increased ultrasounds to speech delays or autism, but when I later found out and DS fell into those categories, I started asking more questions. With DS I think I had an u/s at every appointment. In the beginning that was one per month, starting at week 28 it was every week or two, and at 36 weeks it was twice a week.

My OB wasn't familiar with those studies, but was more than happy to look into it, especially since I wasn't just asking as a fluke. You have to look though at the reason the mother is having frequent ultrasounds. For instance, in my case, I have a high-risk pregnancy because of pre-existing diabetes. I would think in every case of multiple u/s, there is some history of something, whether it's miscarriage, a pre-existing disease...you don't just have multiple u/s for the heck of it--IYKWIM. And it could be the maternal risk factor rather than the multiple u/s adding to the autism risk factor. It's really difficult to know at this point.

My OB stressed that for a typical u/s (we're talking 2D, not the 3D specialty ones), it is sound waves only and hasn't shown any increased risk. For myself, I've had to decide that any risk with the u/s is worth what might be found out with my high-risk pregnancy.

OTOH, if I didn't have any risk factors at all...I would probably still get the first ultrasound for dating purposes (and to hear the heartbeat) and the 20-week Level II ultrasound to make sure all was as okay as it could be. I'm a worrier, and in the end, having the multiple u/s makes me feel as good as I can about what's going on. With DS, I didn't feel him that much, so having a visual that things were okay was helpful to me. This time, I feel the little one kick a lot! But still...

[kusumat]

http://www.midwiferytoday.com/articles/ultrasoundrodgers.asp
http://www.autismtoday.com/articles/ATTN_Researchers.htm
http://merzenich.positscience.com/2007/05/01/ultrasound-and-autism/
http://www.medicalnewstoday.com/articles/49000.php

[ShanaMama]

I am really unfamiliar with the risks of u/s, except as a pp said, blips that I've heard briefly. In any case, I declined my first trimester u/s because I saw no need for it. I was sure of my dates. I do plan on having the 20 week, b/c it reassures me that all is well & because I don't have enough of a reason not to have one.
My thoughts are that it is an intervention whose effects are largely unknown. So I avoid unneccesary ones, but wouldn't refuse a necessary one.
The pp all brought up good points about your dating & possible induction chances. You should discuss these variables with your ob.