Forests are essential for life on earth. Three hundred million people worldwide live in forests and 1.6 billion depend on them for their livelihoods. Forests also provide habitat for a vast array of plants and animals, many of which are still undiscovered. They protect our watersheds.
The other cause is migraine headaches that can affect some women prior to their period following ovulation. Nausea typically accompanies migraines regardless of the cause of the headache. In this case the headaches are caused by the hormonal imbalance and they can be completely debilitating along with the nausea.
Doctors have not pinpointed the exact cause of PMS, but many believe it is linked to changing hormone levels. Following a girl's period, the amounts of estrogen and progesterone (female hormones) in her body increase. Then about 1 week before her period starts, levels of both of these hormones begin to fall. The thinking is that these changing hormone levels can lead to PMS symptoms.