Help calculate if the medication time is during the fetal development sensitive teratogenic period?

Patient's question:

No

Doctor's answer:

Fertilization Day 15 - Around Week 3 of Pregnancy This period is the classic teratogenic period. Your medication time should be during this period. (Counting the first day as the first day of your last menstrual period), but there's no need to worry too much. Make sure to have prenatal check-ups during pregnancy to rule out major malformations.