Primary
Tension-type headache (most common cause)
Migraine headache (2nd most common cause)
Tension-type headache (most common cause)
Migraine headache (2nd most common cause)
Secondary
Postdural puncture headache
Preeclampsia/Eclampsia
Cerebral venous sinus thrombosis
Stroke (ischemic or hemorrhagic)
Ruptured aneurysm or malformation
Posterior Reversible Encephalopathy Syndrome (PRES)<unk>  cerebral angiopathy
Pseudotumor cerebri
SAH
Amniotic Fluid Embolus
Choriocarcinoma
Air embolism
Postdural puncture headache
Preeclampsia/Eclampsia
Cerebral venous sinus thrombosis
Stroke (ischemic or hemorrhagic)
Ruptured aneurysm or malformation
Posterior Reversible Encephalopathy Syndrome (PRES)<unk>  cerebral angiopathy
Pseudotumor cerebri
SAH
Amniotic Fluid Embolus
Choriocarcinoma
Air embolism
Amniotic fluid embolus
Chorioamnionitis
Acute fatty liver of pregnancy
Eclampsia
HELLP syndrome
Mastitis
Peripartum cardiomyopathy<unk>  endometritis<unk><unk>  hemorrhage
Preeclampsia
Resuscitative hysterotomy
Retained products of conception
Uterine rupture
Postpartum headache
Primary
Tension headache
Tension-type headache 
Post-lumbar puncture headache
Migraine headache 
Migraine headache
Cluster headache