What’s going on during that hellish period prelude Two weeks before your PMS period • Your brain’s pituitary gland unloads two fast-acting agents, follicle-stimulating hormone and luteinising hormone, into your bloodstream. Both direct message your ovaries: Drop the package! • Message received. Your ovaries jettison their most mature egg into a fallopian tube. This isn’t NASCAR, though; that egg’s journey to the uterus will take a few days. • In the meantime, your ovaries ramp up oestrogen production. The hormone signals the lining of your uterus to start building a suitable home for an embryo.

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Your body on… PMS Period
What’s going on during that hellish period prelude
Two weeksbeforeyour PMS period
 Your brain’s pituitary gland unloads two fast-acting agents, follicle-stimulating hormone and
luteinising hormone, into your bloodstream. Both direct message your ovaries: Drop the
package!
 Message received. Your ovaries jettison their most mature egg into a fallopian tube. This
isn’t NASCAR, though; that egg’s journey to the uterus will take a few days.

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 In the meantime, your ovaries ramp up oestrogen production. The hormone signals the lining of your
uterus to start building a suitable home for an embryo.
In the next two weeks
 As the uterus builds up tissue and blood supply, your ovaries unleash the key pregnancy-
supporting hormone progesterone. Your body temperature may rise a few degrees, though
you might not even notice. Other side effects, however, aren’t so benign…
 Progesterone also fuels the expansion of the milk ducts in your breasts. Chances are, your
boobs are now swollen and achy. (Women on the Pill may be spared this effect.)
 Progesterone may also interfere with certain brain chemicals, including the mood-
regulating hormone serotonin. And it can stimulate the amygdala, a brain structure tied to
emotion. The result is two charming PMS calling cards: irritability and anxiety.
 Meanwhile, oestrogen and progesterone are also hard at work preparing the womb. Your intestines
may relax a bit to make room for a soon-to-be- occupied uterus. As they expand, so do you (yup,
we’re talking bloating and gas). Changes in your insulin sensitivity could also trigger food
cravings.
As yourPMS periodstarts
 That unfertilised egg has waited around long enough, and your uterus senses all the fuss was
for nothing. Your estrogen and progesterone levels plummet, along with hurray! most PMS
symptoms.
 Yet the fun’s not quite over. Your uterine cells begin releasing chemicals called prostaglandins
that help slough off the extra blood and tissue. They force your uterine muscles to contract a
process otherwise known as cramps.
 Inflammatory in nature, prostaglandins can also cause nausea. (Their production can often
be curbed by exercise or anti-inflammatory meds such as ibuprofen.)
 Though you may feel like you’re gushing for days, the average blood loss during a period is
somewhere between a few tablespoons and a cup.
As yourPMS periodends
 You made it! But ever the optimists, your ovaries start slowly prepping the next egg for
release—so the process can begin all over again.