Protected sex prior to period is very much safe and literally there is no chance of pregnancy
. Though, she needs to confirm it with one home pregnancy test with urine.
Other reasons for delayed period are hormonal
imbalance, stress/ anxiety, thyroid
problem, ovarian cyst
, wt gain/extreme loss, irregular eating habits, psychological factor etc.
Here, she may require some investigations to rule out underlying pathology through USG pelvis scan, thyroid profile & other hormone assay etc. Consult with your gynecologist and take suggestive measures.
Avoid stress / anxiety, take healthy diet with vitamin & iron supplements
, eat more fruits & vegetables , drink plenty water or juice and maintain genital hygiene properly.
If you need further consultation with me, then you can visit http://www.healthcaremagic.com/doctors/dr-soumen-patra/63326.
Take care yourself.