Parturition and Lactation




Parturition: After nine months of pregnancy, the fully developed foetus is ready for delivery. The process of childbirth is called parturition.


Parturition (process of Birth):

Parturition is triggered via a complex neuroendocrine mechanism. Birth signals come from a fully developed foetus and placenta. These signals cause mild uterine contractions. It is called the foetal excretory reflex. This causes the release of oxytocin from the maternal pituitary gland. Oxytocin acts on the muscles of the uterus, causing stronger contractions. These contractions stimulate further secretion of oxytocin. The stimulatory reflex between uterine contractions and oxytocin secretion continues, resulting in progressively stronger contractions. This causes the baby to be expelled from the womb through the birth canal. After the baby is born, the placenta is also drained from the uterus. Secretion of CRH by the placenta increases enormously toward the end of pregnancy. Women who have higher levels of CRH earlier in pregnancy are more likely to deliver prematurely, whereas those who have low levels are more likely to deliver after their due date. After the birth of the child, the size of the uterus decreases, and its lining is rapidly restored. It takes nearly 6 months to return back to pre-pregnant status).

Test Tube Babies:

Test tube baby is a technique concerned to a woman who is not able to conceive to give birth to a normal baby. Test tube babies are not developed in a test tube as the name points out. The term ‘test tube’ refers to ‘in-vitro’ or ‘in glass’ where the fertilization of eggs by sperm is carried out. This technology is called in-vitro fertilization (IVF) technology. IVF technology was pioneered in humans by Prof. Robert Winston. 

Methodology Involves:  

  • Removal of the unfertilized ovum from the reproductive tract of a female. 
  • The egg is kept under aseptic conditions. 
  • Fertilization of eggs in test tubes by sperm (in semen) obtained from males. 
  • The gametes take about 12-15 hours to fertilize. 
  • After fertilization, the zygote is transferred into another fluid medium resembling body temperature. 
  • When the embryo reaches the 32-celled stage, it is implanted into the uterus of another female which serves as the host animal or surrogate mother. 
  • These host animals or surrogate mothers are used only to serve as animal incubators and to deliver off springs after the normal gestation (pregnancy) period. 
  • This results in the normal birth of a baby who is called a test tube baby. 
  • The surrogate mothers don’t contribute anything in terms of genetic makeup since the egg is from the donor mother and semen is from the donor father. 
  • The First attempt to produce a test tube baby was made by an Italian scientist, Dr. Petrucci (1959 A.D.). 
  • Subhash Mukherjee created India's first and the world's second test tube baby using in-vitro fertilization.


Lactation: The mammary glands of the female undergo differentiation during pregnancy and starts producing milk towards the end of pregnancy by the process called lactation.



The mammary glands of the female undergo differentiation during pregnancy. Lactation is the process by which milk is synthesized and secreted from the mammary glands of the postpartum female breast in response to an infant sucking at the nipple. The milk produced during the initial few days of lactation is called colostrum. The colostrum contains various antibodies which are absolutely essential to develop resistance for the newborn baby. Breast-feeding during the initial period of infant growth is recommended by doctors for bringing up a healthy baby. 

Milk Properties:  

  • The milk produced during the early stages of lactation differs from the milk produced after maturation, i.e., when lactation is fully established. 
  • Colostrum is the first milk produced during the first stage of lactation. 
  • After childbirth, the content of milk gradually changes. Within four to five days of labour, the colostrum transforms into transitional milk. 
  • Matured milk is produced in the mammary glands 14 to 15 days after childbirth. 

Lactation Procedure:  

  • Breast growth begins throughout pregnancy and continues to increase in size after childbirth due to the influence of ovarian and placental hormones. 
  • During this time, the breast produces a set amount of milk. 
  • Only after the baby is born does milk secretion increase. 
  • Milk is secreted from the mammary glands during the breastfeeding process.  

What do you think the doctors inject to induce delivery? 

To induce labour pain and delivery, doctors administer oxytocin. The posterior pituitary gland releases oxytocin in response to the foetal ejection reflex, which is begun by a fully formed foetus and placenta. During parturition, oxytocin causes greater uterine contractions (childbirth).

Do you know? What sort of steroids are injected to the mother during pre-mature delivery?  

Steroids, commonly known as corticosteroids, are man-made versions of natural human hormones. When pregnant women receive steroid injections, the substance goes through their bloodstream to the baby's body and lungs. A typical "course" of prenatal steroid treatment consists of two injections spaced 24 hours apart. When administered between 25 and 33 weeks of pregnancy, steroids can significantly accelerate the development of the baby's lungs. This improves the chances of survival for many premature newborns.


Do you Know?

  • Varying creatures have different gestation periods. The gestation time for Asian elephants is 617 days, 58-65 days for dogs, and 58-67 days for cats.

  • The fusing of male and female gametes results in the formation of a zygote. In humans, the zygote is diploid and has 23 pairs of chromosomes, for a total of 46 chromosomes.
If you would like to contribute notes or other learning material, please submit them using the button below. | Human Reproduction Part 7

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Human Reproduction Part 7 [00:30:20]
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