FriendOfDeSoto

Does this make any sense?

Yes.

First they define pregnancy to start before conception.

That’s not what’s happening. This is a statistical math problem and the last, reliably known variable is most likely the last period of the person before conception. That doesn’t mean they were pregnant before conception. If neither the date of the last period nor the date of conception are known, they use a different method, probably ultrasound picture comparisons, and add a lower number.

Seconded! LMMS is a good free DAW to get started.