During a pregnancy, the baby is protected by the ________.

The amniotic sac is a crucial structure during pregnancy as it contains the amniotic fluid which surrounds and cushions the developing fetus. This fluid plays essential roles such as allowing for fetal movements, helping to maintain a stable temperature, and providing a barrier against external pressure or trauma. While the placenta and umbilical cord also provide important functions, such as nutrient and oxygen transfer and waste removal, the amniotic sac specifically serves to protect the fetus from physical shock and potential injury.

In contrast, the placenta connects the mother to the fetus, facilitating the exchange of nutrients and waste, while the umbilical cord serves as the conduit for these exchanges. The fallopian tubes are not involved in protecting the baby during pregnancy, as they are the pathways through which eggs travel from the ovaries to the uterus and are only relevant prior to conception.