DC 2007-04-25, In The Womb 子宫日记 11

They will allow her to develop a sense of self to interact with others, to explore and to learn. The new generation of 4D ultrasound scans continues to provide fresh insight into the behavior of the growing fetus. Technology is advancing and as the experience of practitioners evolves, new light is shed on this once invisible world.

In this image, a 24-week-old fetus seems sticking out her tongue. No one knows exactly why, but it is known that her mouth is full of taste buds, so she could be tasting the amniotic fluid. A fetus's mouth and nose are permanently filled with amniotic fluid that can carry the tastes and smells of the mother's food. Strong flavors pass easily through the placenta into the baby's blood stream and are eventually passed into the amniotic fluid to give the baby an early taste of her mother's cooking. A developed sense of taste and smell could help the baby take her first sips of breast milk once she is born. Just like the amniotic fluid, breast milk contains a similar selection of tastes and smells from the mother's food. If the newborn baby is already familiar with these flavors and likes the taste, this may encourage her to feed.

This scan shows a 24-week-old fetus opening and closing her eyes. The eyes are fully formed halfway through the pregnancy. But seeing is the one sense she can't experience until she is born. It's too dark in the womb. It's possible that some very bright light, direct sunlight for example, could penetrate into the uterus and the fetus may be able to detect a faint glow, but the uterine wall is so thick, buried under a protective layer of skin and fat, that most of the time, the fetus evolves in total darkness. While there may be nothing to see in the womb, opening and closing the eyes helps the fetus develop the blinking reflex, a reflex that stays with us for life to protect our eyes from foreign objects, keep them moist and shield them from bright light.

At 25 weeks, the eyes grow intricate lashes. But there is one detail that may not fully develop no matter how much time the fetus spends inside the womb, the color of the eyes. Some pigments need light to form properly and the baby's eyes may change color during the first month of life. Babies of Asian or African descent are usually born with dark brown or dark grey eyes that mature to deep brown or black. A Caucasian baby almost always has blue eyes in the womb, even if they change to green or brown after birth. Geneticists once believed that a single gene determined eye color. But new research shows that several genes are responsible. So it's impossible to predict just from looking at the parent's eyes what color the baby's eyes will be.

words and phrases:

stick out： 伸出

lash： 眼睫毛

pigment： 色素