First Day Last Period:
Length of Period: Cycle days:
Next Period BeginsEndsFertility BeginsOvulationDue date (If Pregnant)

When is the first day of the menstrual period cycle?

The first day of the menstrual cycle is the first day of your menstrual period and also the very first day you observe bright red blood. (Brown spotting is not considered a menstrual period.)

However, some women who spot several days before their menses may have an issue with hormones and the corpus luteum (short corpus luteum phase).

If you are trying to get pregnant and you have regular spotting before your real period begins, we suggest that in addition to using the ovulation calendar, you also use the BBT (basal body temperature) and an ovulation detection tool in order to find out when you can get pregnant. If you have a lot of spotting you might want to talk to your OB/GYN and assess your progesterone level shortly after presumed ovulation.

What happens during a menstrual cycle?

The menstrual cycle begins with the first day of bleeding and ends the day before the next menstrual bleeding.

  1. There are essentially two halves of the menstrual cycle:
  2. The follicular phase, when the follicle develops inside the ovary
  3. The luteal phase after ovulation when the corpus luteum develops in the ovary in the area from where the egg was ejected.

During the follicular phase, the levels of estrogen (the "female hormone") start to rise. Estrogen plays an important role in keeping you healthy, especially by helping keep bones strong as you get older. Estrogen also makes the lining of the uterus (womb) grow and thicken. This lining of the womb is a place that will nourish the embryo when a pregnancy occurs. At the same time, an egg in one of the ovaries starts to mature. On about day 14 of an average 28-day cycle, the egg leaves the ovary. This is called ovulation, and it is at this point that the follicular phase begins.

If it gets fertilized, the fertilized egg travels through the fallopian tube to the uterus. Hormone levels rise and help prepare the uterine lining for pregnancy. A woman is most likely to get pregnant from having sex during the 3-4 days before or on the day of ovulation. Women with cycles that are shorter or longer than average may ovulate before or after day 14. 

If a pregnancy occurs, the egg is attached to the uterine wall. If the egg is not fertilized, and no pregnancy occurs, the egg will break apart and get absorbed. Then, hormone levels drop, and the thickened lining of the uterus is shed during the menstrual period bleeding. 

Pelvic Pain One Week Before Menstrual Period

Cyclical pain, pain that's related to the menstrual cycle, in a reproductive age woman, almost always has something to do with hormones and ovulation. Any abdominal or pelvic pain occurring monthly should be examined to see what changes in anatomy and physiology may be responsible for causing the pain.

Many times the diagnosis of such pain can be difficult. The exact timing of when and how long the pain occurs in relation to a monthly menstrual cycle can often be a clue as to what types of pathology to look for during testing.

What causes pain to occur 7-10 days before your period?

In the week or two prior to a menstrual period, a corpus luteum cystic gland forms on one of the ovaries at the site where an egg was released from that ovary. This is a hormonally functional gland that produces progesterone primarily. The gland causes the ovary to become larger and heavier for a while until the cystic area goes away when your period starts.

The other main pelvic change during this time is that the veins of the pelvis often swell (dilate) under the influence of progesterone. They can become like varicose veins of the pelvis and sometimes will produce a throbbing pain, which lasts throughout most of the last week of the cycle.

Since the pain only lasts for 3 days and does not start 14 days before  the menstrual period but rather 7-10 days, the best guess as to cause would be that the pain has to do with the enlarging ovary on the right. One would expect the pain to alternate sides if it were due to a corpus luteum gland because ovulation usually alters one month from one ovary and one month from the other. However, we have seen ovulation occur pretty regularly from only one ovary even though there appears to be no disease in the other one.

Pain occurs when the enlarging ovary "pulls" on any adhesions of the ovary to the surrounding tissue or simply when it stretches the ovarian capsule fairly rapidly. Adhesions cannot be seen on ultrasound or any X-rays but if you have your pelvic ultrasound during the 3 days you are having pain, a small cystic area may be seen on the ovary.

How to Calculate Menstrual Cycles Manually

  1. Get a calendar. This can be either a paper calendar or one on a  computer, phone, or tablet.
  2. Mark the FIRST day of your LAST period with an "X". This is day #1.
  3. Count forward however many days your menstrual cycle normally is before you start. If you don't know, then just count 28 days.
  4. Put your initials or some other identifying mark on the last day. This is when your next period should start.

That's it! If you have never monitored your period before, after several months you'll be able to figure out your actual cycle length and adjust your calculations accordingly.

Read More: Is your menstrual cycle normal?