Premature birth is a significant medical, social and economic problem worldwide. In the 21st Century in developed countries, this problem accounts for over two thirds of neonatal deaths. In Bulgaria, statistics show that 10-12% of all pregnancies end with premature birth. Despite the number of studies in this field and the efforts made by obstetricians and gynecologists, the tendency to increase the number of preterm births has continued in the last decade. Its consequences are multiple complications who lead to a high neonatal mortality in the national and global world. Preterm birth is characterized by complex and vague etiology. A specific cause of premature birth can not be defined, but a set of risk factors is considered, divided into three main groups of etiological factors: socio-economic, medical-biological, and behavioral. Associated with preterm birth socio-economic and behavioral risk factors include poverty, unemployment, low education, poor prenatal care, harmful habits such as smoking, alcohol, drugs and other harmful substances, unhealthy family environment, severe and prolonged stress, excessive physical exercise (lifting weights), trauma (hits or violence), new pregnancies less than 6 months after previous birth, unhealthy diet and low mother BMI, etc. Essential for the preterm birth is also the medico - biological etiological factors. One of these is uterine enlargement, as the main reason for this may be the presence of: multiple pregnancies that occurred naturally or after using assisted reproductive technologies or polyhydramnios (increased amount of amniotic fluid). Other risk factors include: placenta previa, incorrect position of the fetus, myoma, uterine cervix malformations (including cerebrovascular insufficiency), preeclampsia, uterine contractions, acute infections during pregnancy (vaginal - chlamydia, trichomonas, mycoplasma , toxoplasmosis, bacterial vaginosis, viral rubella, cytomegalovirus, herpes, influenza, adenovirus infection, chronic diseases (hypertension, cardiovascular diseases, diseases of the lungs, liver or kidney anemia and etc.), genetic factors, previous premature birth, etc. These risk indicators are subject to detailed analysis in the work of a number of authors. To limit preterm births, a number of studies have been conducted to identify and identify the risk factors that are relevant to it. Identifying and recognizing their effects and impact leading to premature birth will significantly reduce the severe health, economic and social consequences as well as reduce the risk of neonatal death. In order to reduce the frequency of preterm births, adequate and specialized prenatal care is essential. They must be individually tailored for each particular case of pregnancy and take into account the complex of risk predispositions.
Malocclusion and prematurity at birth.