Table 3 Simple and Multivariate Poisson Regression for low birth weight year by year, and adjusted for each variables (maternal age, maternal educational level, prenatal visits, gestational age, and mode of delivery yearly), and all variables together in Brazil and its regions, according to the 26 state capitals and Brazil’s capital, Brasília, between 1996 and 2011

Year

1.009

1.007

0.998

1.003

1.007

1.002

(1.008;1.010)

(1.006;1.008)

(0.997;0.999)

(1.001;1.004)

(1.006;1.009)

(1.002;1.002)

Year and maternal age

1.010

1.007

0.998

1.003

1.008

1.002

(1.009;1.012)

(1.006;1.008)

(0.997;0.998)

(1.001;1.004)

(1.006;1.009)

(1.002;1.003)

Year and educational level

1.014

1.011

1.004

1.010

1.011

1.008

(1.012;1.015)

(1.010;1.012)

(1.003;1.005)

(1.008;1.011)

(1.010;1.012)

(1.007;1.008)

Year and prenatal care

1.011

1.009

1.013

1.018

1.014

1.010

(1.010;1.012)

(1.008;1.010)

(1.012;1.014)

(1.016;1.019)

(1.013;1.016)

(1.010;1.011)

Year and gestational age

1.006

0.990

0.990

0.991

0.993

0.992

(1.004;1.007)

(0.989;0.991)

(0.989;0.990)

(0.990;0.992)

(0.992;0.994)

(0.991;0.992)

Year and mode of delivery

1.010

1.009

0.998

1.002

1.008

1.003

(1.009;1.012)

(1.008;1.01)

(0.998;0.999)

(1;1.003)

(1.007;1.009)

(1.002;1.003)

Year and all variables

1,005 (1,004;1,006)

0,994 (0,993;0,995)

0,996 (0,995;0,996)

0,999 (0,998;1,001)

0,994 (0,992;0,995)

0,995 (0,995;0,996)