If an ultrasound at 14 weeks showed your due date as Oct 2 and 20 the same but a 28-week scan gave Sept 23 could you have conceived before Dec 12?

Based on the information you have provided, it is unlikely that you conceived before December 12. Here's an explanation:

14-week ultrasound: The ultrasound at 14 weeks estimated your due date as October 2. This estimation is based on various measurements taken during the ultrasound, including the size and development of the fetus.

20-week ultrasound: The 20-week ultrasound confirmed the due date of October 2. This further supports the accuracy of the initial estimation.

28-week scan: The 28-week scan provided a different due date of September 23. This discrepancy could be due to several factors, such as measurement variations, fetal growth rate changes, or potential errors during the ultrasound.

Conception date: To calculate the possible conception date, you need to count back approximately 38 weeks (or 266 days) from the estimated due date.

Considering the due date of October 2, the 38-week window would be:

October 2 (estimated due date) - 38 weeks = December 14 (possible earliest conception date)

Therefore, the earliest possible conception date based on the October 2 due date would be December 14.

However, since the 28-week scan provided a different due date of September 23, the conception date would shift earlier to accommodate this new estimation.

Calculating from September 23, the 38-week window would be:

September 23 (new estimated due date) - 38 weeks = December 12 (new possible earliest conception date)

Therefore, based on the 28-week scan, the earliest possible conception date would be December 12.

In conclusion, while the initial ultrasound estimations suggested a possible conception date of December 14, the later scan's revised due date shifts the potential conception window, making it unlikely that conception occurred before December 12. It's important to discuss these discrepancies with your healthcare provider for further clarification.