Conversation: The conversation between human and AI assistant.
[|Human|] I didn t have an ultrasound till i was 29 weeks pregnant. The ultrasound said that i m due on august 28 and that i concevied on december 5. I either conceived at the end of november or on december 6. Is there any way to know if the ultrasound is correct or when i really conceieved?
[|AI|]  Ultrasounds at 29 weeks are not as accurate as we would hope them to be. Once babies reach approximately 18 weeks, they start growing at different rates. It's difficult to know if your baby is actually 28 weeks and is big, or is 30 weeks and is small, or is 29 weeks and right on. Ultrasounds at 29 weeks can be up to 2-3 weeks off, actually. The estimation of 29 weeks is just that, an estimation. In short, no, it is not entirely possible to know the exact date you conceived 27 weeks previously.