The graph below shows the concentration of progesterone in a woman's blood during the early stages of pregnancy - NSC Life Sciences - Question 2 - 2018 - Paper 1

The general trend observed in progesterone levels during the early stages of pregnancy is an increase over time. Starting from 21.6 ng/ml at 4 weeks, the progesterone level rises progressively, peaking at 39.5 ng/ml by the 14th week.

The negative feedback mechanism that takes place involves high levels of progesterone inhibiting the secretion of Follicle Stimulating Hormone (FSH). As progesterone levels rise during pregnancy, they signal the body to reduce FSH production, which prevents the maturation of additional follicles and ovulation.

This negative feedback mechanism is crucial as it helps to maintain pregnancy by preventing further ovulation, ensuring that the body focuses on nurturing the developing fetus rather than preparing for another potential pregnancy.

To calculate the percentage increase in progesterone from week 4 to week 14:

Initial progesterone level at week 4: 21.6 ng/ml Final progesterone level at week 14: 39.5 ng/ml Change in progesterone = 39.5 - 21.6 = 17.9 ng/ml Percentage increase = ( \frac{17.9}{21.6} \times 100 = 82.87% \approx 82.9% )

A possible reason for the decrease in progesterone levels in week 16 could be that the placenta is starting to take over hormone production or there might be an impending miscarriage or other complications.

One way this problem could potentially be treated is by administering progesterone supplements to help maintain adequate hormone levels during the pregnancy.