Menstrual Cycle Reproductive Phase

Reproductive Phase

The reproductive phase of life in humans is different for males and females. In humans, males and females become sexually active when they reach adolescence. At this stage of life, they become capable of reproduction. For males the testes and for females, the ovaries begin to produce gametes. The capacity for maturation and production of gametes lasts for much longer in males over females. In males, production of sperms start at the age of between the age of 12-16 and continue throughout the entire lifetime. The phases of female reproductive cycle start around 10-12 years of age and last till 45-50 years. The ova or the egg begins to mature with the onset of puberty. One ova matures and is released by the ovary every 28-30 days. 

During this period, the wall of the uterus becomes thick so it can receive the egg (in case the egg is fertilised and begins to develop). A fertilised egg results in pregnancy and if it is not fertilised then the released egg and the thickened lining of the uterus along with the blood vessels are shed off. This takes place through a process known as menstruation and it generally occurs every 28-30 days. The first menstrual flow that begins at the start of puberty is known as menarche and it continues till 45-50 years (give or take). The stoppage of menstruation is known as menopause. At first, the menstrual cycle can be irregular, however, in time, it becomes regular.


Women's Reproductive Life Cycle- Menstrual Cycle Phases

The day count for the menstrual cycle in adolescent females begins on the first day of menstruation when blood comes out of the vagina. The entire length of the cycle is around 28 days (taken as an average in all females). The entire duration of one menstrual cycle is divided into 4 phases. These are the following:

  1. Menstrual phase (Day 1 to 5)

  2. Follicular phase (Day 1 to 13)

  3. Ovulation phase (Day 14)

  4. Luteal phase (Day 15 to 28)


  1. Menstrual Phase

  • The menstrual phase starts on the first day of the menstruation and continues until the 5th day of the menstrual cycle.

  • It starts as the uterus shed the inner soft tissue and blood vessels which exits the body from the vagina as menstrual fluid. 

  • Around 10 ml to 80ml of blood loss takes place.

  • Adolescent females may experience abdominal cramps during this phase which are caused by the contraction of the uterine and the abdominal muscles to expel the menstrual fluid.

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  1. Follicular Phase

  • The start of the follicular phase coincides with the first day of the menstruation. However, the phase lasts until the 13th day of the complete menstrual cycle. 

  • In this phase, the pituitary gland secretes a hormone that stimulates egg cells in the ovaries to grow.

  • One of the egg cells starts to mature in a sac-like structure called the follicle and it takes full 13 days for the egg cell to reach complete maturation.

  • When the egg cell matures the follicle secretes a hormone that stimulates the uterus to develop a lining of blood vessels and the endometrium (soft tissue)

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  1. Ovulation Phase

  • This stage takes place on the 14th day of the cycle.

  • The phase starts as the pituitary gland secretes a hormone that causes the ovary to release the mature egg cell which is then swept into the fallopian tube. This takes place with the help of the cilia of the fimbriae. 

  • Fimbriae are finger-like projections which are observed at the end of the fallopian tube close to the ovaries. The cilia are hair-like projections found on the fimbriae.

  • Ovulation is triggered by LH.

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  1. Luteal Phase

  • The luteal phase begins on the 15 the day of the menstrual cycle.

  • The mature egg cell is released during the ovulation and the follicle is ruptured and it stays on the surface of the ovary.

  • In the next two week and the follicle transforms into a structure known as corpus luteum. 

  • The corpus luteum at this time releases progesterone with small amounts of oestrogen. The hormones maintain the thickened line of the uterus whilst waiting for a fertilised egg to implant on the wall.

  • If a fertilised egg is implanted on the wall of the uterus, it starts producing hormones which are necessary to maintain corpus luteum. (one such hormone is human chorionic gonadotropin) 

  • If pregnancy does not occur then the egg cell disintegrates along with the corpus luteum. (Corpus luteum withers and dies). There’s a drop in progesterone levels which causes the lining of the uterus to fall away in a process called menstruation and then the cycle starts again.

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FAQ (Frequently Asked Questions)

1. What Are the Stages of Reproduction in Humans?

The stages of human reproduction can be divided into three stages. These are


First Trimester: It lasts till the first three months with the fertilisation of the egg cell by a sperm. The fertilised egg turns into a zygote which eventually multiplies and then moves to the fallopian tube. The zygote then turns to morula when it contains 16 cells and a blastula which contains 100 cells. The blastocyst continues to grow on the uterine lining

In the first month, the organs start to differentiate and the limbs become apparent in the second month. The embryo turns into a foetus in the third month.


Second Trimester: All the organs are developed in the first three months. In the second three months, the bone structure develops. The brain also starts maturing in this stage.


Third Trimester: In the last three months, the brain structure is perfected and the baby grows larger. The mother’s natural antibodies also pass to the foetus during the last trimester. 

2. What is

  • PMS

  • Dysmenorrhoea

  • Amenorrhoea

PMS: PMS or Pre-Menstrual Syndrome are hormonal events before a period and can trigger a range of side-effects which can put any women at risk. These risks include fluid retention, fatigue, irritability and headaches. Some treatments are exercise and dietary changes.


Dysmenorrhoea: In general terms, this condition is a culmination of painful periods. The reason is thought to be that the uterus is prompted by certain hormones to squeeze harder than necessary to dislodge the endometrium lining. The condition can be treated with the usage of pain-alleviating medicine.


Amenorrhoea: It is the absence of menstrual periods. It is considered abnormal except during pre-puberty, pregnancy, lactation and post-menopause. Some of the reasons are excessive exercise or high/ low body weight.