Could the doctor be off by 8-9 weeks?

Question

I had sex on July 5th and got my period the next day. It was a normal period. I had a normal period in August and September too. I am VERY regular. I had sex again in late September, specifically the 21st and 23rd Then I missed in October and thats when I found out I was pregnant. During the first ultrasound in Oct, the doctor couldn't detect the baby at all although I had what he called a pregnancy sack. The next week I went back and there was the form of the baby. They put my due date at June 15th. Is it possible that the doctor is off by 9 weeks? Could I have gotten pregnant in July? Because the conception date and my last menstrual period adds up to a June due date if I got pregnant in late September. Even when I went for my gender ultrasound at 19 weeks 4 days, the sonographer said that I was even less pregnant and he put me at 18 weeks 3 days. I guess I just want to know what the margin of error is for the doctor. Is it as big as 8-9 weeks?

Answer 1

It might be a week or two, but not 8 or 9. That's two whole months!

The earlier the ultrasound is done the more accurate it will be. In the first weeks to months, the baby will grow on a pretty strict schedule which allows the doctor to accurately judge how far along you are based on things like whether he can plainly see arm or leg buds or if the heart is beating.

Later on, sometime around 20 weeks and later, it gets more difficult to judge accurately because the outside is pretty much formed and the baby is working on the inside parts that the doctor can't see too well.

That said, based on what you said about the ultrasounds, I would guess that the doctor was pretty close the first time.

If you had gotten pregnant in July and had an ultrasound in October, the baby would be fully visibly on the screen. I had my first ultrasound at 10 weeks and it was a miniature baby already. He had arms and legs already and we could see him moving around. We could also detect he heartbeat and measure him and everything.

There's no way that you could have been that far along and only had an empty sac visible.

I'm guessing that maybe you are trying to work out who the father is? I really hope that's not what this is about, but it sounds like it.

Answer 2

From your dates that you gave, you're due around the 15th of June. If you went for an ultrasound in October and they couldn't detect the baby yet, that would have meant you were only several weeks pregnant. Its hard to detect a pregnancy via ultrasound prior to 6-7 weeks. If you have conceived in July, your baby would have already been a couple months old and plainly visible. I think the doc is right. You conceived on your September dates. Best of luck hun!

Answer 3

The margin of error is not 8-9 weeks...it is more like 1-2 weeks. But they are usually not off by that much. Ultrasounds up to about 17/18 weeks are usually right on...once you get past this mark, babies grow at different rates, so it is harder to tell. He/she could have a growth spurt, and then slow down for a little while.

I would say you are due in June. Dont worry and stress about it. Have fun and enjoy it!!! Trust me right now is the easy part. I am 30 weeks, and it is no longer fun!!!

Answer 4

I doubt if you could have gotten pregnant in July. I got pregnant on July 5th and Im now 33 weeks along and by August I was already able to hear a heartbeat, etc....You say they couldnt detect one in Oct at first, so Im sure you got pregnant at the end of September.

Answer 5

Yep. I still think my doc is off about 4 weeks cause my last period was VERY short. I am also said to be due around July 13th!