A menstrual cycle usually lasts about 28 days and is divided into 3 phases, according to the hormonal changes that occur in the woman's body during the month. Menstruation represents the fertile years of a woman's life, which begin in adolescence and last through to menopause.
It is normal for the duration of the cycle to vary between 25 and 35 days, but cycles with shorter or longer intervals than these may be associated to health problems such as polycystic ovaries, so if this happens it is recommended you consult a gynecologist.
Menstrual cycle calculator
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When your menstrual cycle is irregular, it is more difficult to know the day of ovulation and this may make getting pregnant a bit more difficult, because your fertile days can not be accurately calculated. See how to calculate your fertile days with an irregular cycle.
Phases of a normal menstrual cycle
A normal menstrual cycle lasts, on average, 28 days, beginning on the first day of menstruation and ending when the next month's menstruation begins. Each cycle is divided into 3 phases:
1. Follicular phase
This is the first phase of the cycle, which starts on the first day of menstruation and lasts 5 to 12 days. At this stage the brain increases the production of follicle-stimulating hormone (FSH), which causes the ovaries to mature their eggs.
With this maturation, the ovary also begins to release higher amounts of estrogen, which is another hormone, responsible for making the lining of the uterus ready for a possible pregnancy.
2. Ovulatory phase
At this phase, estrogen levels continue to increase and make the body produce the luteinizing hormone (LH), which is responsible for selecting the more mature ovum and getting it out of the ovary, which is when ovulation occurs around the 14th day of the cycle.
Once released, the egg travels through the tubes until it reaches the uterus. Normally, the ovum survives for 24 hours outside the ovary and therefore, if it comes in contact with sperm, it can be fertilized. Since sperm can last up to 5 days inside the woman's body, it is possible that if the woman has had intercourse up to 5 days before ovulation, she may become pregnant.
3. Luteal Phase
This phase occurs normally in the last 12 days of the cycle and during these days the follicle, left by the ovule inside the ovary, begins to produce progesterone in greater quantity, to continue preparing the lining of the uterus in the case of a possible pregnancy. There is also an increase in estrogen production and therefore some women may have breast tenderness, mood swings and even feel bloated.
When fertilization does not occur, the follicle shrinks inside the ovary, so the levels of estrogen and progesterone decrease until the lining of the uterus is eliminated, starting your period and your next menstrual cycle.
If fertilization does occur, the egg is embedded to the walls of the uterus and the body begins to produce hCG, a hormone that keeps the follicle producing estrogen and progesterone at high levels to keep the lining of the uterus until the placenta is formed.
Signs that indicate your most fertile days
The signs that indicate your most fertile days are clear discharge similar to egg white, increased breast tenderness and mild pain in the uterus, similar to a mild and transient cramp.
It is also possible to identify ovulation through an ovulation pharmacy test, such as Clearblue and Aminosense.
What causes an irregular menstrual cycle
An irregular menstrual cycle is when you don't know when your menstruation will come. The most common causes of an irregular cycle are:
- Early fertile life in adolescence, up to 2 years after your first menstruation;
- Post-pregnancy phase;
- Perimenopause, due to intense hormonal changes;
- Eating disorders that cause excess weight loss, such as anorexia;
- Excessive physical activity, especially in female athletes;
- Polycystic ovaries;
- Changing your contraceptive method;
- Stress or emotional disturbances;
- Presence of inflammation, polyps or tumors in the reproductive tract.
In the presence of an irregular menstrual cycle or when the menstrual cycle does not occur for more than 3 months, one should seek out a gynecologist to investigate the cause of the problem. See 20 period myths.