Prenatal vitamin: once a day. Check your OB regarding her/his prescription.
Due day is decided by combining the information of your last menstrual
periord, sono date, weeks from sono. If you have irregular period and unsure
last menstrue period, age decided by sono is very important.
If you have regular period (28-30 day), the due day is calculated from the
first day of your last period: 280 days instead of 266 days.