Until the end of the 16th week, the placenta grows. At term, ratio of weight of fetus to weight of placenta is:
**Core Concept:**
The placenta is a vital organ in pregnancy, responsible for gas exchange, waste removal, and nutrient supply between the mother and the fetus. Its growth and development are essential for fetal well-being. In the first trimester, the placenta grows rapidly, reaching its maximum weight by the end of the 16th week. In the second and third trimesters, the placenta maintains its size while the fetus grows significantly. The ratio of fetal weight to placental weight at term is crucial for understanding placental function and fetal development.
**Why the Correct Answer is Right:**
At term, the correct answer is **D**. By the end of the 16th week, the placenta reaches its maximum weight due to rapid development during the first trimester. After that, the placenta maintains its weight while the fetus grows significantly. As a result, the ratio of fetal weight to placental weight becomes more significant at term. This ratio is important as it reflects the efficiency of placental function and nutrient and waste exchange between the mother and fetus.
**Why Each Wrong Option is Incorrect:**
A) Option A is incorrect because the placenta does not grow significantly after the first trimester and maintains its weight throughout pregnancy.
B) Option B is incorrect as the placenta does not decrease in size but maintains its weight while the fetus grows substantially.
C) Option C is incorrect because the placenta maintains its weight but the fetus grows significantly, leading to an increased ratio of fetal weight to placental weight at term.
**Clinical Pearl:**
The understanding of the placental weight-to-fetus weight ratio at term is crucial for assessing the efficiency of placental function, which is essential for fetal well-being. An optimal placental efficiency is vital for fetal growth, nutrition, and waste removal, ensuring a healthy pregnancy outcome.