Baby Size/Due Date Question

[trimestersdoula]

Ok so here is what is going on. A girl I know was supposed to be due June 9th. They gave her this due date based on babies development at first ultrasound and because she KNEW when her last period was and KNEW when she ovulated.

She was just at the doctor for an ultrasound the other day and now they are telling her that the baby is due June 2nd because of the size.

We all know ultrasounds aren't great at judging weight and that they are better at figuring out due date in the early months of pregnancy.

She is NOT due June 2nd IMO, she is due the 1st due date that they gave her. It worries me because she is the type to jump the gun if it comes to the baby being overdue, which it won't really won't be when they decide it is overdue.

What do you think. How can I tell her without getting her mad at me.

[olive&pimiento]

U/S can be off by a week on either side in the first trimester, two weeks on either side in the second trimester and three weeks on either side in the third trimester. I do not know why her due date would be changed, but I would fight it if I were her, especially if this is her first baby! This is just setting her up for a failed induction c/s at "42" weeks.

[midwifemom3]

Maybe the provider didnt notice that she had an early U/S, Just ask her to review with them the first sono. Her date should not be moved

[jeninejessica]

My mothers due date with my youngest brother was changed THREE times. She started Novermber 1st, then November 9th, then November 14th.

He ended up coming out (on his own, no induction), November 27th, weighing 7lbs14oz. That's almost a whole MONTH after what they first told her was her due date. Thankfully she kept saying no to induction after the 14th, who knows, maybe her actual due date wasn't til the 28th.

If she KNOWS when ovulation was, then I would fight hard for them to keep that due date. Just tell her that you noticed this, and thought it was odd, so you did some reading, and this is what you came up with. That you just want the best start for baby, and him being forced out early isn't a nice welcoming present!

[turtlewomyn]

Not a birth professional here, but a similar thing happened to me. I was originally due October 3, I knew when I ovulated and conceived and that date was correct. I had an ultrasound at 12 weeks and they moved my due date up by ten days based on the size. I went past that due date, another U/S, weight was estimated at 9lb10oz and I was coerced into a scheduled c-section for fetal macrosomia by my CNM and her OB. The section was on October 3, her original due date, so 41w3d according to them, 40w according to me. Don't let this happen to your friend.

I guess I would just gather some information about the accuracy of u/s in late pregnancy, even OB websites say to use the date decided at the earlier U/S. All you can do is give her the information, she will have to decide what to do with it.

[mothercat]

OK, first I am a birth professional (FWIW).
I don't have the link in front of me, but at every stage of ultrasound from figuring using the meaurements to determine the due date (software), to the tech who does the measuring there is a built in presumption of error +/- 10%.

The software used to give the due date is mostly based on the work of Hadlock who based growth on the presumption that since the average birth weight in the US is 7.5 pounds then all babies should be about 7.5# at birth. If the baby is genetically predisposed to be petite then the due date keeps getting moved out farther or mom is labeled as high risk for IUGR because your baby is not allowed to weigh 5# at birth. If the baby is meant to be large, then the due date keeps getting moved up, because your baby is not allowed to weigh 10# at birth.

The due date should be accurately set from the earliest possible information (LMP and date of conception, if known) and confirmed by ultrasound if there is any doubt beyond about 7 days. If the US shows that baby is +/- 7 days within the due date given by the US measurements (up to 19 weeks), always, always, always use mom's LMP/conception. And no changing it!

I had this happen a few weeks ago. Mom had a small first baby and was labeled IUGR. I helped her with the second baby. No dates to work with, so we used the US dating at 20 weeks. Turns out her babies are not IUGR, they are petite. Second baby weighed same as the first and came out a month early (by US dates). She was fine and we avoided an unnecessary trip to the hospital for a premature (by US) baby.

Sorry, if I sound cranky. IMHO, if HCP's are going to use technology to bully and scare people they should at least know what they're talking about.

Linda, CNM

[Romana]

I'm not a birth professional either.

I know within a couple of days when ovulation/conception occurred. I had one 20 wk u/s that put my due date "back" by about a week. However, I talked with my midwife about it, and since I'm quite confident within a few days of ovulation/conception, we left the due date the same, at the later date. Knowing when the baby was conceived is more accurate than the 20 wk u/s, which can be off by 2 weeks or so.

It always bothers me when OBs switch due dates based on 20 wk u/s, or worse, 30 or 35 wk u/s. At the 35 wk, though, it's usually more like, "Oh gosh, you're going to have a GIANT baby! We should induce at 37 wks."

FWIW, I grew my first baby a bit large - she was 8 lbs when born spontaneously at 38 weeks. So that measurement @ 20 wks may be correct, but as mothercat pointed out, it shouldn't move my due date, kwim?