title: [The infants with very low birth weight and extremely low birth weight-obstetrics and medico-social problems].
authors.forename: K
authors.initials: K
authors.lastname: Tzvetkov
authors.forename: N
authors.initials: N
authors.lastname: Mircheva
authors.forename: M
authors.initials: M
authors.lastname: Monastirska
authors.forename: E
authors.initials: E
authors.lastname: Zheleva
mesh_terms: D002031:Bulgaria; D036861:Delivery, Obstetric / Q000379:methods / Q000401:mortality; D005260:Female; D006801:Humans; D052577:Infant, Extremely Low Birth Weight; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D011247:Pregnancy; D012940:Social Problems