What is a major fetal development characteristic at 16 weeks gestation?

At 16 weeks gestation, a notable characteristic of fetal development is that teeth begin to form. During this stage, the primary dentition, which includes the baby teeth, is starting to develop beneath the gums. The dental lamina, a layer of epithelial cells, begins to differentiate into the teeth structures, indicating that the foundation for future tooth eruption is being laid down. This process is vital as it establishes the dental anatomy that will be important for feeding and nourishment after birth.

While the development of brown fat occurs as the pregnancy progresses and is crucial for thermoregulation in neonates, it typically becomes prominent later in gestation. The lanugo, or fine hair, does cover the fetus but usually starts developing around 14 to 16 weeks but does not cover the entire body at this time; it develops more fully as gestation advances. The fetal weight at this point is generally less than the stated 450 grams, as average weights are typically closer to 100-200 grams around this period. Understanding these development markers provides insight into normal prenatal growth and the timeline of fetal anatomical changes.