Pregnancy

For being a mother, a woman has to go through various stages in life. Let’s see the stages involved in the childbirth starting from pregnancy followed by parturition and lactation.

Pregnancy

Pregnancy occurs when the sperm fertilizes the egg, and the zygote is formed. The zygote gets implanted in the wall of the uterus. As soon as the implantation takes place, the need for nourishment and care arises as the growth of the zygote develops into an embryo which further grows into a baby. This responsibility is taken up by a layer formed between the baby and the mother, called the placenta. The placenta is formed by finger-like projections called chorionic villi and the uterine tissue.  This layer plays many roles during pregnancy, which are briefly discussed as follows:-

  • Providing nutrients and oxygen to the growing fetus.
  • It also removes the waste materials given out by the fetus substituting the function of the digestive system and the excretory system.
  • The placenta releases hormones like human placental lactogen, progesterone, estrogen, human chorionic gonadotropin and relaxin which are necessary for the growth of the fetus.
  • The umbilical cord that connects the fetus to the placenta helps in transportation of substances required for growth from the mother to the fetus.

Pregnancy

As soon as the implantation takes place, the fertilized cell mass or embryo starts showing the triploblastic nature of human beings by dividing into the three layer of cells. This gives rise to different organs during development – ectoderm, mesoderm, and endoderm.

All these steps after implantation lead to the development of the baby and it takes nine months in humans. The development is very gradual and steady. At first, the heart of the embryo is formed, followed by limbs, major organs, the appearance of hair and so on. By the end of 9 months, the fetus is completely developed.

Parturition

It is the process of the contraction of the uterus at regular intervals that helps in the delivery of the baby at the end of pregnancy. The signals that the fully developed fetus sends through the placenta for ejection is called Fetal ejection reflex. These signals induce muscular contractions.

The time period from fertilization to childbirth is called the gestation period.

Lactation

It is the process of production of milk by the mammary glands at the end of pregnancy. The milk produced initially by the glands is called colostrum. This milk is crucial for the baby as it provides the child with the initial immunity.

This was a brief explanation of pregnancy, parturition, and lactation.

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Practise This Question

Identify the placental hormone from the following.