Why cannot a woman get pregnant again during pregnancy?

Options

A. A woman ovulates during pregnancy, but the oviducts are plugged with protective mucus to prevent sperm from entering
B. High level of hCG in woman's bodies kill sperm.
C. A woman cannot have intercourse during pregnancy due to the presence of a protective mucus plug that develops in the cervix.
D. High levels of estrogen and progesterone, secreted by the corpus luteum or placenta during pregnancy. Inhibit the secretion of gonadotropins and prevent ovulation.

Answer

To understand why a woman cannot get pregnant again during pregnancy, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Understanding Hormonal Changes During Pregnancy**:
- During pregnancy, a woman's body undergoes significant hormonal changes. The levels of two key hormones, estrogen and progesterone, increase dramatically.

2. **Source of Hormones**:
- These hormones are primarily secreted by the corpus luteum (a structure formed in the ovary after ovulation) and later by the placenta as the pregnancy progresses.

3. **Role of Estrogen and Progesterone**:
- The high levels of estrogen and progesterone serve multiple functions, one of which is to maintain the pregnancy by preparing the uterine lining and preventing contractions.

4. **Inhibition of Gonadotropins**:
- The elevated levels of estrogen and progesterone inhibit the secretion of gonadotropins (such as LH and FSH) from the pituitary gland. Gonadotropins are essential for regulating the menstrual cycle and stimulating ovulation.

5. **Prevention of Ovulation**:
- Since gonadotropins are inhibited, the process of ovulation (the release of an egg from the ovary) does not occur during pregnancy. Without ovulation, there is no egg available for fertilization.

6. **Conclusion**:
- Therefore, due to the hormonal changes and the inhibition of gonadotropins, a woman cannot become pregnant again while she is already pregnant.