below is a rough outline for a regular cycle. Many women experience
irregular menstrual cycles. You can tell if you have an irregular
cycle if your period comes sporadically. Although this is natural,
especially for younger women, you might want to talk to your provider
to make sure your cycle isn’t affected by another condition.
Some women use birth control pills to even out their cycles, which
can also control symptoms of PMS.
The first day of the cycle is the day your period starts. Of course,
this won’t happen if the egg was fertilized, because that
means you’re pregnant. Otherwise, you usually know when to
expect day one (about every 28 days). Some women experience the
most severe cramps on the first day, that’s because the uterus
is contracting to push the blood and tissue and the unfertilized
egg out and through the cervix. The bleeding will last from three
to five days usually, but anywhere between two and seven days can
The first half of your cycle, from the start of your period until
about day 14, is the “estrogen phase” because the level
of estrogen in your body is rising throughout these two weeks.
FSH is the hormone that causes estrogen to be produced by your
ovaries as they prepare an egg for ovulation.
Toward the end of this time, from about day 7 to day 14, the egg
is growing and the estrogen is stimulating the uterus to thicken
with blood and extra tissue.
Around day 13 to 15, you experience ovulation. Ovulation happens
when the ovaries release an egg in response to a luteinizing hormone
surge from the pituitary gland in your brain. Some women are in
tune with their bodies enough to sense ovulation, perhaps through
mittleshmerz (cramps) or a very slight rise in body temperature.
The egg travels through the fallopian tubes and toward the uterus.
When the egg is in the fallopian tubes, fertilization is most likely.
After ovulation, progesterone is produced.
The second phase of your period is called the “progesterone
phase.” That means the cycle is now controlled by the hormone
progesterone. The uterus continues to prepare for pregnancy. This
is the time when you are most prone to PMS symptoms, the hormones
are increasing up until around the time the unfertilized egg is
expelled from your body. The egg eventually gets to the uterus,
and if it isn’t fertilized, then day one arrives once again.