Signals for Parturition

The signals for parturition, the process of giving birth, originate from both the fully developed foetus and the placenta. Let us understand this in detail.

Role of the Foetus

- The foetus plays an important role in initiating the process of parturition.
- The foetal adrenal gland secretes a hormone called cortisol, which increases towards the end of pregnancy.
- Cortisol stimulates the production of enzymes that convert progesterone to oestrogen in the placenta.
- Oestrogen plays a crucial role in preparing the uterus for labour by promoting the growth and differentiation of uterine muscle cells.
- Oestrogen also stimulates the secretion of prostaglandins, which are hormones that cause the cervix to soften and dilate.
- Thus, the foetus indirectly signals the onset of labour by stimulating the production of cortisol and oestrogen.

Role of the Placenta

- The placenta, the organ that connects the foetus to the mother's uterus, also plays a role in parturition.
- As the foetus grows, the placenta's function starts to decline, and it produces less progesterone.
- The decrease in progesterone levels in the mother's body triggers the production of oxytocin, a hormone that causes the uterus to contract.
- The placenta also produces prostaglandins that cause the cervix to soften and dilate.
- Thus, the placenta signals the onset of labour by reducing the production of progesterone and producing oxytocin and prostaglandins.

Conclusion

In conclusion, the signals for parturition originate from both the fully developed foetus and the placenta. The foetal adrenal gland produces cortisol, which stimulates the production of oestrogen and prostaglandins, while the placenta produces oxytocin and prostaglandins by reducing the production of progesterone. Together, these signals initiate the process of labour and help the mother give birth to her baby.

Parturition is induced by signals from both the fully developed foetus and the placenta. It induces mild uterine contractions called foetal ejection reflex.