Final answer:
The health of the fetus depends on the placenta and umbilical cord, which facilitate the exchange of oxygen and nutrients. Fetal hemoglobin has a higher affinity for oxygen, aiding in efficient uptake. Maternal health, placental function, and other factors can impact fetal growth and birth weight.
Step-by-step explanation:
The discussion involves several factors that are critical for fetal development and survival. Fetal blood circulation relies heavily on the placenta and umbilical cord, both of which facilitate the transfer of oxygen and nutrients from the mother to the growing fetus. The umbilical vein carries oxygen-rich blood from the placenta to the fetus, while the umbilical arteries return oxygen-depleted blood to the placenta. Fetal hemoglobin's higher affinity for oxygen compared to adult hemoglobin is a key adaptation that enables efficient oxygen uptake. Factors such as maternal health, placental conditions, and overall blood flow, including uterine blood flow and mother's oxygenation, as well as negative influences like smoking, can impact fetal growth and birth weight, possibly leading to conditions like intrauterine growth restriction (IUGR).
After birth, the newborn's circulatory system undergoes significant changes as the lungs begin to function, and the umbilical vessels close, marking the transition from fetal to postnatal life.