At Natural Cycles, we count the pregnancy starting from the detected ovulation day – this is when the egg is fertilized by the sperm and conception happens.
Your pregnancy weeks are then calculated by adding 14 days to your ovulation day.
The 14 days are added to align with how healthcare professionals calculate your due date. The healthcare system counts the pregnancy weeks starting on the first day of your last period, assuming that ovulation happens on CD14. However, many people don’t ovulate on Cycle Day 14, since all cycles are different.
Later in pregnancy, how far along you are is determined by ultrasound – but again, this isn’t directly linked to the ovulation day. This is why the due date you get from your midwife may differ from Natural Cycles’ due date.
In the Today view, you will see the count of weeks + days since the start of the pregnancy.
However, in the Pregnancy tab, you will see the general overview of the week that you are currently in. For that reason, the week number in the Pregnancy tab will always be higher than the week number in the Today view.
To illustrate this: if you are on week 12+3 days, this would mean that you are in the 13th week of the development of the baby (week 13).