Name the hormonal composition of the oral contraceptive used by human females. Explain how does it acts as a contraceptive.

Explanation

### Step-by-Step Solution:

1. **Identify the Hormonal Composition**:
- Oral contraceptives used by human females typically contain two main hormones: **estrogen** and **progesterone**. Some formulations may contain only **progesterone** (known as the mini-pill).

2. **Mechanism of Action**:
- **Prevention of Ovulation**: The primary way oral contraceptives prevent pregnancy is by inhibiting ovulation. The hormones in the contraceptive pills signal the body to prevent the release of an egg from the ovaries.
- **Prevention of Implantation**: In addition to preventing ovulation, these hormones also create an environment in the uterus that is less favorable for implantation. This means that even if fertilization occurs, the fertilized egg (blastocyst) is less likely to attach to the uterine lining.
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