Fetus

Definition

A fetus is the developing stage of a mammal after the embryonic phase, typically occurring from the ninth week of gestation until birth. This stage is marked by significant growth and differentiation of tissues and organs, making the fetus capable of independent survival once parturition occurs. Understanding the fetal development process is crucial as it encompasses critical periods of growth, organogenesis, and functional maturation.

5 Must Know Facts For Your Next Test

1. Fetal development involves three trimesters, each characterized by distinct growth patterns and milestones in organ development.
2. During the second trimester, significant developments include rapid growth, the formation of recognizable features, and the beginning of fetal movements.
3. By the end of the third trimester, a fetus typically weighs between 5 to 10 pounds and is about 18 to 22 inches long, preparing for birth.
4. Fetal viability refers to the point at which a fetus can survive outside the womb, generally around 24 weeks of gestation due to lung and organ maturity.
5. The placenta plays a crucial role in supporting fetal development by providing nutrients, oxygen, and waste removal while also producing hormones that regulate pregnancy.

Review Questions

• Explain how fetal development progresses through the trimesters and what major changes occur during each stage.
  • Fetal development progresses through three trimesters, each with significant changes. In the first trimester, critical structures like the heart and major organs begin to form. The second trimester sees rapid growth and the development of recognizable facial features and limbs. Finally, in the third trimester, the fetus gains weight and prepares for birth, with organs maturing to support independent life outside the womb.
• Analyze the role of the placenta during fetal development and its importance in maintaining pregnancy.
  • The placenta serves as a vital organ during fetal development, facilitating nutrient and oxygen transfer from mother to fetus while removing waste products. It also produces hormones essential for maintaining pregnancy and regulating maternal physiology. Any dysfunction in placental function can lead to complications such as preeclampsia or fetal growth restriction, underscoring its importance in healthy fetal development.
• Evaluate how external factors can impact fetal development and potentially influence outcomes at birth.
  • External factors such as maternal nutrition, exposure to toxins, stress levels, and infections can significantly impact fetal development. For instance, malnutrition can lead to low birth weight and developmental delays, while exposure to teratogens can cause congenital disabilities. Understanding these influences is crucial for promoting healthy pregnancies and improving neonatal outcomes, emphasizing the need for proper prenatal care.

Related terms

Gestation: The period during which an embryo or fetus develops inside the uterus, typically lasting around 40 weeks in humans.

Parturition: The process of giving birth, involving a series of events that lead to the delivery of the fetus.

Embryo: The early stage of development following fertilization, typically from conception until the end of the eighth week.