PHAN TiCH MOT SO YEU TO LIEN QUAN DEN TY LE SINH CON THUT BA TROT LEN CAO TAI MOT SO XA MIEN NUI TINH THAI N G U Y I N PHAM H N G H A I , NGUYEN DllTC TRpNG, O d VAN DUNG T6M TAT Nghidn cuv dugc tidn hdnh trdn 299 dp vg chdng dd tudi sinh dd lai M(ic tidu Phin tich mdt s6 yiu td lidn quan ddn ly Id sinh thir ba tr& Idn cao tai hai xd niidn niii tiiudc huydn Vd Nhai, tinh Thdi Nguydn Phuxyng phdp nghicn cuu Piidn tich cdc yiu td lidn quan sir dung test x' OR (Odd Ratio) Ket qud Sd cdp vg chdng tnDng dd tudi sinh dd tai hai xd nghidn cuu chiim 19.9% Ty Id hd nghdo cao (46.1%) Sd hd gia dinh cd thu- ba tr& Idn chidm 12%, ty sd gi&i tinh sinh 154 trd sa sinh trai/100 trd sa sinh gdi Cd mil tidn quan khd chdt chS giO'a mdt sd yiu td vd vide sinh thw ba lr& Idn d& ydu td kinh ti v&ip < 0.05 OR = 2.2 ddn tdc (p < 0,05 OR = 2,12), kiin tliuc, s y hliu biit ciia ngw&i ddn vi cdc bidn phdp trdnh thai (p < 0,05; OR = 0.4), quan diim phdi c6 trai ndi ddi tdng dw&ng (p < 0,05 OR = 2.78) hdnh vi khdng dp dung bidn phdp trdnh thai (p < 0.05: OR = 2.59) alQ-a quan diim ddng nhidu phCic lim nhieu cua (v&i p < 0.05 OR = 2,59) C6 5.7% khdng hdi Idng vd thdi dd ciia cdn bd truyin thdng vd 14,4% khdng hdi Idng vd trinh dd vd ky ndng truydn thdng cua cdn bd y ti Tir khda Vd Nhai thir ba, ddn sd ki ho$ch hda gia dinh SUMMARY The study was carried out on 299 couples in the reproductive age Objective: Analysis some factors related to the rate of the third child or more in remote mountainous communes in Vo Nhai distnc Thai Nguyen province Research Methodology Analysis of related factors, using the x^ test, OR (Odd Ratio) Results: The number of couples of reproductive age in two communes studies is 19.9% High poverty rate (46.1%) The households with three or more children accounted for 12%; sex ratio at birth 154 newborn sons per 100 newborn giris Having rather tight correlation between a number of factors with the third child or more, including, economic factors with p