I have mild pulmonary hypertension and i am 13 weeks pregnant, could the pregnancy have caused the ph?

Maybe: Intravascular volume goes up by 20-30% during pregnancy. Depending your other medical issues, prior cardiac/pulmonary function that might result in an increase in pulmonary pressures. It does warrant follow during the pregnancy (with an additional echo/doppler) to see if the readings have normalized, or remain elevated. Large increases in pulmonary pressures can increase maternal and fetal risk.

Pulmonary htn: It could be related, actual cause need more information.