What Causes Headache After First Delivery?

my wife aged 24weight 57kgs after giving birth our first baby she developed frequent head ache problem when inquired verbally showing her symptoms to her gynecologist she was told that she is suffering from migraine . Now she is suffering with head ache almost every day and its intense some times she will not get relief even after taking a pill and now we have two children and both children were born by operation. Please suggest the remedy