How is conception date calculated by doctors?
Hi, my last period came 30 days ago, and my cycle is typically 28 days. My hCG level 2 days ago is 9821. When was my likely conception date?
Dear Crystaline
The date of conception is likely to be around 16 days ago. This is because in a typical menstrual cycle of 28 days, ovulation occurs around day 14.
This is assuming that everyone’s biological clock does not change from month to month.
However, in the real life situation, there might be some variation depending on stress levels, change of sleep cycles, drastic dietary changes etc.
You should also be fairly certain of your last menstrual period. Some may mistake early pregnancy bleeding for a “normal”period and hence get confused about when exactly they got pregnant.
An ultrasound measurement of the pregnancy is able to date the pregnancy fairly accurately (within +/- 5 days) in the first 12 weeks of pregnancy and that should provide possibly the best estimate of your conception date.
Hope this helps.
Best regards
Dr Fong Yoke Fai
Thank you crystaline for sharing your new pregnancy, and congratulations!
Based on your information: expected due date is 2nd February 2019.
Usually the gynaecologists will do a dating scan to find out some measurements of your baby with ultrasound - that might be a more accurate estimate of the due date.
