I thought I’d explain why your OB calculates your pregnancy from the 1st day of your last period. My fiancé is confused, I see a lot of women on here asking why it’s not calculated from date of conception.

Week 1. Your period. You are shedding your uterus lining.

Week 2. At least one of your eggs are ripening.

Week 3. Ovulation. Your egg is released from your ovary and is ready to be fertilised.

Week 4. Your baby is growing into a placenta.

You’ve only conceived during week 3, but your body has been making a baby since week 1.