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Preterm birth has become one of the leading causes of infant mortality. The WHO estimates that 15 million premature babies are born and 1 million newborns die each year worldwide.
Preterm birth has become the 1st cause of death for children under 5 years of age on the mainland and is one of the major threats to children's health.
What is a premature baby?
Preterm birth refers to a person who has reached 28 weeks' gestation but less than 37 weeks (196-258 days) and delivered a newborn at this time, which is called preterm.
Pregnant in October, once delivered, but some babies have not yet reached full term, they come to the world early to find their mothers.
Premature babies due to early birth, immature development of body organs, prone to a variety of diseases, and long-term prognosis is closely related to the backward development of the brain, bronchopulmonary dysplasia, premature retinopathy, etc., resulting in many disabilities and sequelae.
Moreover, premature babies, because they did not get various nutrients that should have been transported by the mother's placenta in the third trimester of pregnancy, faced the challenges of insufficient living ability and disease after birth, difficulty in eating themselves, and increased nutritional needs, so it is easy to have the problem of growth and development retardation, which will also affect their long-term intelligence level and cognitive ability.
What are the causes of preterm birth?
The cause of preterm birth is less clear. The risk factors associated with preterm birth are as follows:
1 infection
(1) Chorioamnion infection:
It is a very important cause of preterm birth. Infections are mainly caused by cervical and vaginal microorganisms, and some from intrauterine infections. Pathogens include aerobic and anaerobic bacteria, Chlamydia trachomatis, Mycoplasma and so on. Many reports suggest that Streptococcus b and bacteroides in anaerobic bacteria are common strains of infection. Mycoplasma urealyticum is a common pathogen.
There is a lot of research on the mechanism by which infection causes preterm birth. It is now thought that infection causes preterm birth due to bacterial endotoxins stimulating cytokines produced by the fetal membranes.
Cytoactive factors associated with preterm birth include IL-1, TNF, and IL-6. Platelet activators in amniotic fluid have an enhancing effect on the activation of cytokines. Platelet activators are produced by the fetal lung and fetal liver.
The fetus therefore appears to have a promoting effect on preterm birth caused by a bacterial infection, which may favor the fetus in rescuing itself from the infected environment.
(2) Non-reproductive tract infectious diseases:
Fever reactions such as pyelonephritis, pneumonia, malaria, influenza, etc., can activate the activity of prostaglandins to cause contractions.
2 Premature rupture of membranes
Infection is also an important factor in the premature rupture of membranes, which often coexist with premature rupture of membranes, which makes premature birth inevitable. 57% of preterm births occur after premature rupture of membranes, especially those with complicated infections after premature rupture of membranes, and the chance of preterm birth is greater.
3 The uterus is over-inflated
In twin or multiple pregnancies, excessive amniotic fluid can cause high intrauterine pressure and premature delivery.
4 Cervical orifice is incomplete
In patients with congenital cervical dysplasia and cervical injury or tearing for various reasons, cervical sphincter-like function is weak.
After the second trimester, in the process of extending the isthmus and forming the lower uterus, the internal cervical opening is relaxed or the continuity of the cervical connective tissue is destroyed, while the intraaminoperal pressure gradually increases, the uterine orifice is passively dilated, the amniotic sac is expanded from the cervical canal and exposed to the outer cervical opening, and finally due to infection and increased intrauterine pressure leading to rupture of the fetal membrane and premature birth.
5 Uterine hypoplasia
Uterine malformations such as the uncornuated uterus, double uterus, uterine mediastinum, and saddle-shaped uterus all result in late miscarriage or preterm birth due to uterine dysplasia.
6 Pregnancy complications
(1) Hypertensive syndrome of pregnancy:
Severe pregnancy hyperpsia such as preeclampsia or eclampsia are critically ill and can endanger the lives of mothers and children and have to terminate pregnancy in time, resulting in iatrogenic preterm birth.
(2) Placenta previa and placental abruption:
Central placenta previa often has vaginal bleeding around 30 weeks' gestation, and despite aggressive and conservative treatment, it is difficult to maintain pregnancy until term. Placental abruption endangers the mother and baby, and in principle, the pregnancy needs to be terminated immediately, if it occurs before 37 weeks of pregnancy, premature birth occurs.
(3) Intrahepatic bileosis during pregnancy:
It occurs because estrogen reduces the liver's transport of organic ions, thereby impairing the function of liver cells and causing cholestasis in the capillary bile ducts in the central region of the lobules of the liver.
There is also cholestasis in the placental tissue, in which bile acids stimulate the uterus and its decidua to release prostaglandins, resulting in contractions leading to premature birth.
In addition, due to the accumulation of bile in the placental villous space, resulting in impaired nutrient exchange between mother and child, which can lead to fetal distress, and in severe cases, pregnancy must be terminated immediately, if it occurs before 37 weeks, it is premature.
7 Pregnancy comorbidities
Pregnancy with chronic nephritis, pregnancy with heart disease, pregnancy with hepatitis and pregnancy with lupus erythematosus, etc., on the one hand, due to medical comorbidities can cause the mother's systemic ischemia and hypoxia, placental perfusion is also insufficient, easy to induce premature birth; on the other hand, the seriousness of the disease brings danger to the mother, for the safety of the mother to cause iatrogenic preterm birth.
8 Environmental factors
(1) Smoking: How much is directly proportional to the incidence of preterm birth, the more smoking, the higher the preterm birth rate.
(2) Alcohol consumption and drug use: Excessive alcohol consumption during pregnancy, especially in spirits or drug users, directly increases the incidence of preterm birth.
(3) Others: air pollution, water pollution, climate change, regional differences, family relocation, mood swings, etc., can increase the secretion of catecholamines in the body, promote uterine contractions and trigger preterm birth.
9 Psychological factors
Many scholars have found that psychological stress is directly related to preterm birth. Such as family disharmony, child aversion, poor economic conditions, etc. can seriously affect the mood of pregnant women.
Its mechanism may be related to adrenotropin-releasing hormone-mediated release of prostaglandins from placental tissue.
10 Genetic factors
A history of previous preterm birth is clearly associated with subsequent preterm births. In 1995, Kristensen et al. analyzed 13,967 pregnancies in Danish women, which were almost consistent with this.
Women with a history of preterm birth are not only at risk of recurrence of preterm birth themselves, but this danger is also passed on to their children.
Wang (1995) and Polller (1996) among others found that there was a family gathering phenomenon in preterm birth. In addition, there are racial differences in preterm births, and the rate of preterm birth is 50% higher among blacks than whites in the same socioeconomic status. Therefore, it is believed that preterm birth is related to heredity.
How to prevent preterm birth?
Reasonable rest, reasonable exercise, maintain sufficient sleep time, maintain a pleasant and stable mood, keep the room quiet, avoid anxiety, fear, avoid sudden mental trauma and other adverse stimuli to induce premature birth.
Reasonable diet: Pregnant women should strengthen nutrition, diet to high calories, high protein, high vitamins and rich in minerals, appropriate amount of fat, in order to strengthen the nutrition and supply of the fetus. Eat high-fiber, high-vitamin foods, especially vegetables and fruits, drink more water, ensure the supply of water and crude fiber, and keep the stool unobstructed and anti-constipation.
Eliminate various factors that cause increased abdominal pressure, such as constipation, coughing, holding your breath, etc., and do not stimulate the nipples to avoid causing contractions.
Pay attention to personal hygiene. Actively prevent and treat urinary tract and genital tract infections.
Actively prevent the occurrence of pregnancy complications and complications, and prevent premature rupture of membranes and subclinical infections. If abdominal pain is accompanied by vaginal running water, immediately lie flat and raise the hips to avoid the umbilical cord coming out and endangering the life of the fetus.
The left recumbent position and regular oxygen inhalation can increase the maternal blood oxygen concentration, so that the oxygen and nutrition supplied to the fetus are also increased accordingly.
Patients with lax cervical inlet should be ligized at 14 to 18 weeks of gestation, and tocolytic inhibitors may be used in patients with aura of preterm birth.
Self-counting fetal movements, understand the situation of the fetus in the womb, if there is abnormal fetal movement, abdominal pain, vaginal bleeding and other situations immediately report to the medical staff.
About the author
Yang Sili
Dali First People's Hospital
Obstetrician-Gynecology Attending Physician
Introduction: Graduated from Chuanbei Medical College in 2013 majoring in clinical medicine, engaged in clinical work for more than 8 years. He has traveled to learn professional knowledge in and out of the province many times. He has published more than 10 medical papers. He served as a member of the Publicity Committee of the Second Branch of Surgery of the First People's Hospital of Dali City, a member of the Professional Committee of Childbirth Analgesia of the Yunnan Eugenics and Excellent Breeding Maternal and Child Health Care Association, participated in eight scientific research projects in Dali City, and participated in the development of five new technology projects in Dali Prefecture and won the second and third prizes respectively.