IWAB whilst I agree in part, I also disagree.
On starting periods, young Women experience symptoms and changes that are different; and as a consequence are often associated with stress regarding the unfamiliar.
As a Mother of Daughters; I try to convey that change is stressful and they are changes that will take time to assimilate. I bring a lifetime of experience of menstruation to guide my DDs in valid choices.
Increased/reduced bowel activity and digestive discomfort is oft associated with menstruation. As are increased/reduced energy levels.
I entirely disagree that the pill is the way to go. I also disagree that the benefits outweigh the risks.
The risks are not clearly identified; and in fact valid research is lacking. We simply don't know.
I will revise my advise in my earlier post; it was sweeping and generalised.
OP. Look at your DD's diet and fluid intake. One of my Daughter's cut out water/fluids when she was having pre-menstrual bloating ( a logical response); and was having constipation/tummy problems as a consequence.
Her period discomfort has reduced since she increased water and fibre before and during her period. Both expands the bowel.
A young Woman should know her body, her cycle before medicating it.
The Pill is not without harm.
Years ago there was a "spoof" medical article (all the data about the female pill); but it was presented as a new Male contraceptive . The medical profession rose in uproar to ban it.
It's an easy prescription for any GP; but that doesn't make it right.