No　large　population-based　study　has　focused　on　both　maternal　paternal　risk　factors　for　low　birthweight　(LBW)　in　China.　We　aimed　to　identify　parental　risk　factors　associated　with　LBW.　A　population-based,　retrospective　cohort　study　was　conducted　on　202,725　singleton　infants　at　37-42　weeks.　These　term　singleton　newborns　were　classified　as　LBW　with　birthweight　＜=　2500　g(TLBW)　and　normal　birthweight　between　50th　to　97th　percentile　(TNBW　50th-97th)　according　to　Chinese　singleton　norms.　Multiple　logistic　regression　analyses　were　used　to　find　those　parental　risk　factors　of　LBW　by　comparing　two　groups.　TLBW　and　TNBW(50th-97th)　occupied　4.8%　and　70.8%　of　the　study　population,　respectively.　Logistic　regression　showed　a　significant　association　with　positive　maternal　hepatitis　B　surface　antigen　(RR　=　1.979,　P　=　0.047),　irregular　folic　acid　intake　(RR　=　1.152,　P　=　0.003),　paternal　history　of　varicocele　(RR　=　2.404,　P　=　0.003)　and　female　babies　(RR　=　1.072,　P　=　0.046).　Maternal　smoking,　hypertension　and　history　of　stillbirth　were　found　related　to　LBW　but　no　statistically　significant.　Positive　maternal　hepatitis　B　surface　antigen,　irregular　folic　acid　intake,　paternal　history　of　varicocele　had　a　negative　effect　on　birth　weight.　Measures　are　necessarily　taken　to　avoid　them　to　improve　pregnancy　outcomes.　Further　studies　should　be　done　to　investigate　each　detailed　risk　factors　on　LBW.