DC 2007-05-02, In The Womb 子宫日记 14

The baby's heart beats about twice as fast as her mother's. Monitoring her heartbeat gives a good indication of her general condition. The mother's heart rate and blood pressure are directly affected by her emotional state. If she's calm, her heart slows down and her blood pressure drops. If she's tense and stressed, her heart beats faster and her blood pressure rises.

Although the fetus has her own separate blood supply, these increases in heart rate and blood pressure are easily passed through the placenta and have a direct impact on the baby. It takes a while for the effects to filter through, but when the mother is recovering from the impact of stress and her heat rate is returning to normal, her baby's heart begins to race, as the physiological effects of stress creep through the placenta.

In the short term, stress in the mother can lead to low birth weight or premature birth. But it's also possible that the mother's prolonged anxiety and stress can be passed on, establishing a tendency for stress in the child, and making her more likely to develop chronic health problems, such as heart disease and diabetes. It can even have a harmful effect on the child's mental development in the early years of her life.

By now, the mother can feel her baby move every day. Usually, it's the fetus kicking or pushing. But sometime she may feel the regular twitch of her baby's hiccups. Hiccups are an involuntary sudden contraction of the diaphragm. Why fetus has hiccup is a bit of a mystery. One theory is that it's a reflex that may help a baby latch on to a nipple and feed. The spasm of a fetus's hiccup is strong enough to feel. But unlike our own hiccups, it makes no sound at all. The sound of an adult hiccup is made by the sudden rush of air that's stopped by the closure of the vocal cords. But in the fetus's lungs, there is no air, hence, no hiccup sound.

The last of the major organs to form are the lungs. The lungs don't function during the time in the womb. All the fetus's oxygen is delivered from the mother's blood via the placenta. Inside the fetus's lungs, the branching network of tubes is filled with amniotic fluid during the entire time in the womb. And the tiny air sacs that will extract oxygen from the air remain closed. But the fetus still makes breathing movements with her lungs and diaphragm. This strengthens the chest muscles, so they are ready to expand and fill the lungs with air the moment the baby is born. Most fetuses that reach 26 weeks will make it through to birth with no problem. They simply put on weight and continue to exercise their reflexes and senses.