Ultrasound gestational age

[luckiec7]

I'm confused by the ultrasound gestational age. I believe I conceived the weekend of 9/27/14. Based on an ultrasound on 12/11/14 I was 10 weeks 5 days and on 1/9/15 I was 14 weeks 6 days. They're consistent with each other but it puts my due date as July 4 and conception 2 weeks later than I thought. Am I wrong or is the ultrasound measuring me incorrectly?

[laurawr_madeline]

It depends if your cycle was regular or not, if not you may have ovulated late that month which is why you would be measuring 2 weeks late.

[luckiec7]

I was taking the pill so my cycle should have been regular.

[ninjarowyn]

I get confused too. Based on my last period I should've been due July 24th. After the ultrasound she said I was a week ahead of where we thought we were and am now due July 17th but that doesn't make sense based on the dates of the period. Strange!

[ashley_july123]

Ultrasounds can be off a Lil.. I know it was for my last baby,, it said I was measuring a week or two ahead but I ended having my baby 4days later,, my doc never changed my due date,, but I wouldn't worry to much about that,,

[shay0921]

After the egg fertilizes it takes 6 to 12 days for the fetus to implant. Once the egg implants is when pregnancy begins sooo depending on how long it took ur egg to implant can throw off the dates. Going by size is the most accurate way so ur doc is prolly right.

[luckiec7]

Wouldn't the gestational age take into consideration the implantation time? Would it take an additional 2 weeks to implant?

[kmcb8288]

You can still ovulate late even if you're on the pill, which you probably did. Early ultrasounds are usually pretty accurate, especially when you have more than one.

[luckiec7]

Thank you. I have another ultrasound 2/6/15 for the anatomy scan. Hopefully I can get some more clarification then. I know every pregnancy is different and I've heard both that it's normal for the ultrasound to be 2 weeks off and that when they're done early that they're pretty accurate so it's hard to know what to believe!

[kiara_avesu]

Sometimes the baby can grow at a different rate as well. My baby showed as 6wks 3 days. Then we had to get an emergency ultrasound the next week and baby was the correct 7wks4days. Based on that our Baby should have measured 9wks4 days at our next ultrasound but they were showing 10wks so I guess they hit a growth spurt. Lol

[lila29]

My MFM doctor told me that the gestational age determined by the ultrasound include the 2weeks prior the ovulation date which give us 40weeks of pregnancy. In all hospital and countries, doctors measure the gestational age beginning by the first day of your last period!
Actually, they measure this way because we are never sure when the fecondation occurs!

[luckiec7]

I'm concerned because based on 40 weeks I would have conceived Oct 10. I had sex with my bf the weekend of Sept 26 then not again until Oct 15. I should have been ovulating the weekend of Sept 26 but even if I was a few days late ovulating I would have had to ovulate within the first couple days of Oct in order for the sperm to be viable.

[lila29]

There is the gestational age which include the 2weeks prior the ovulation and the conceptional age which is measured from the first day of the fecondation ( the fecondation can occur until 3-4 days after the ovulation).
In all the countries, the pregnancy is measured starting from the first day of the last period as it is more accurate for them to follow the progress of the pregnancy. That's why the pregnancy length is 40weeks = 9months and 2weeks (the 2weeks prior ovulation are included in the 40 weeks)