Post-natal period of development occurs after hatching or birth while pre-natal period of development occurs before hatching or birth.

Answer

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Post-natal Period**: This refers to the time after birth or hatching. In humans, this typically lasts for about six weeks after childbirth.
- **Pre-natal Period**: This refers to the time before birth or hatching. In humans, this occurs while the fetus is developing inside the womb.

2. **Significance of the Post-natal Period**:
- The post-natal period is crucial for both the newborn and the mother. During this time, both are at a higher risk for complications, making it a vulnerable period.
- Special care is required to ensure that the newborn grows healthily and that the mother recovers properly.

3. **Understanding the Pre-natal Period**:
- The pre-natal period involves the development of the fetus inside the mother’s womb. The fetus receives nutrition through the placenta, which is essential for its growth.
- In egg-laying organisms, the embryo develops inside the egg, where it gets nourishment from the yolk.

4. **Conclusion**:
- The statement that the post-natal period occurs after hatching or birth and the pre-natal period occurs before hatching or birth is correct. The definitions and implications of both periods highlight their importance in the developmental stages of organisms.