Post-term infants

　　The etiology of overdue infants has not been fully clarified to date and is often related to the following factors:

　　1. Excessive progesterone and insufficient estrogen in the late pregnancy period;

　　2. Frequent bed rest, insufficient activity;

　　3. Abnormal fetal position and fetal malformation;

　　4. Good nutritional conditions, excessive vitamin E;

　　5. Genetic factors and individual constitution;

　　6. Weak uterine contractions.

　　The main clinical problem of overdue infants is the overage, degeneration of the placenta, multiple infarctions, and villous degeneration, leading to placental insufficiency syndrome. The fetus may not receive enough nutrition from the mother and consume a large amount of soft tissue. Due to placental insufficiency, overdue infants are prone to asphyxia during delivery (asphyxia and resuscitation); meconium aspiration syndrome (respiratory system disease), which can be extremely severe in overdue infants. Because the amniotic fluid has decreased, the aspirated meconium is not diluted; due to insufficient glycogen reserve at birth, neonatal hypoglycemia may occur; because anaerobic metabolism rapidly consumes the remaining glycogen reserve, the occurrence of asphyxia during delivery will worsen hypoglycemia.

　　Overdue infants with good placental function have a good clinical appearance, active eyes, fair skin, resembling a newborn a few days after birth, with abundant subcutaneous fat, longer nails, coarser hair, and the disappearance of lanugo. The cartilage of the ear lobe is elastic, and the nipples are prominent.

　　Overdue infants with insufficient placental function mainly manifest as the disappearance of amniotic fluid, progressive hypoxia, and intrauterine malnutrition of the fetus, which are divided into three stages according to the degree.

　　The amniotic fluid disappears, and the epidermal cornification layer can become soft due to the loss of amniotic fluid protection, dry after birth, and become wrinkled, cracked, and peeled.

　　Based on the first stage, hypoxia progresses progressively, intestinal peristalsis accelerates, the anal sphincter relaxes, and meconium is excreted, so the umbilical cord, amniotic membrane, and skin are stained with meconium, and the respiratory tract inhales meconium-amniotic fluid.

　　In addition to the above symptoms, due to the long-term excretion of meconium in the amniotic fluid, the fetus's nails, amniotic fluid, skin, and umbilical cord can all become yellow-green.

　　Pathological changes:Overdue infants, due to the gradual aging, calcification, and increased infarct areas of the placenta, the weight of the placenta decreases, the intervilous space becomes narrow, the wall of the villous blood vessels thickens and closes, the placental function decreases, and the fetus grows and compresses the uterus, causing the uterine blood flow to slow down and the uterine blood supply to decrease, leading to progressive hypoxia.

　　Systematic prenatal checks should be done for overdue infants, and attention should be paid to the mother's weight. If there is a downward trend in the continuous measurement of estriol, termination of pregnancy should be considered.

　　Children born past their due date with normal placental function have a good prognosis. Due to the harder skull, smaller fontanelles, narrow skull sutures, and poor molding ability of the child's head, it is more likely to cause dystocia. If the placental function is insufficient, the incidence and mortality rate are higher than usual, especially for second-stage symptoms in overdue infants, due to acute hypoxia, aspiration of amniotic fluid contaminated with meconium, which often results in severe respiratory symptoms or hypoxic intracranial hemorrhage.

　　The clinical examinations of post-term infants have the following two types:

　　First, prenatal examination of pregnant women

　　1. Judgment of placental function: ①fetal movement count; ②hPL determination; ③urine E3 ratio determination; ④ultrasound examination, including biparietal diameter, placental function grading, amniotic fluid volume, etc.; ⑤amnioscope examination; ⑥NST, OCT test, etc.

　　2. Fetal electronic monitor detection.

　　3. Ultrasound detection.

　　4. Amnioscope examination.

　　Second, fetal examination after delivery

　　1. Blood gas analysis.

　　2. Chest X-ray examination.

　　Pregnant women should meet the supply of high-quality protein foods such as milk, eggs, liver, fish, and lean meat. If conditions do not allow, some of them can be replaced with soy products.

　　Eat more fruit; such as hawthorn, fresh jujube, orange, pomelo, lemon, persimmon, peach, and so on, various fresh vegetables such as carrots, green peppers, tomatoes, eggplants, and various green leafy vegetables are rich in various vitamins and inorganic salts, and should be varied as much as possible and fully consumed.

　　The staple food should be a combination of coarse and fine grains. In addition, 1-2 times of food rich in iodine should be interspersed each week, such as kelp, jellyfish, sea cabbage, nori, shrimp paste, and shrimp, and fish.

　　Avoid spicy and刺激性 food. Such as alcohol, strong tea, coffee, etc., seasoning should not be too strong, because too much salt is easy to cause edema.

　　To prevent the danger caused by insufficient placental function of the post-term placenta in advance, it is necessary to consider terminating the pregnancy in time. The gestational age and expected delivery date should be rechecked, and induction should be performed if it is confirmed to be post-term.

　　Prepare for the rescue of neonatal asphyxia before delivery, so that the newborn can be timely intubated and the foreign bodies in the trachea can be cleared, and oxygen therapy can be given.

　　Always pay attention to the unobstructed airway. For those with amniotic fluid and meconium aspiration, oxygen therapy should be given early, and artificial respiration can be used for those with insufficient oxygen supply that cannot be relieved, and acidosis should be corrected, and energy should be supplemented to prevent hypoglycemia. Antibiotics should be administered to prevent infection.