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Table 2 Distribution of maternal characteristics in the first and last years of the series and AAPCa of low birth weight among single newborns for each stratum of the variables studied, Brazil and its regions according to the 26 state capitals and Brazil’s capital, Brasília, between 1996 and 2011

From: Temporal evolution of the risk factors associated with low birth weight rates in Brazilian capitals (1996-2011)

Variables 1996 2011 AAPC (95 % CI) P 1996 2011 AAPC (95 % CI) P 1996 2011 AAPC (95 % CI) P
  North Northeast Southeast
Maternal age (years)
 10–17 years 14.9 11.3 - - 11.4 9.0 - - 8.0 7.0 - -
 ≥35 years 4.7 8.6 - - 6.4 10.9 - - 9.7 15.3 - -
 18-34 80.3 80.0 - - 82.2 80.2 - - 82.2 77.7 - -
 LBW 10–17 years 10.2 10.6 0.1 (−0.9;1.2) <0.001 9.9 10.7 0.2 (−0.5;0.9) 0.037 11.9 10.9 −0.5 (−1.5;0.4) 0.227
 LBW ≥35 years 6.6 8.6 1.8 (1.0;2.6)a <0.001 7.7 9.0 0.6 (0.2;1.1)a <0.001 11.0 9.3 −0.9 (−1.1;−0.6)a <0.001
 LBW 18–34 6.0 7.0 1.1 (0.5;1.8)a <0.001 6.6 7.4 0.8 (0.5;1.1)a <0.001 8.3 7.6 −0.4 (−1.2;0.4) 0.001
Educational level (years)
 <8 years 64.2 28.3 - - 62.3 26.2 - - 48.9 19.5 - -
 ≥12 3.0 16.4 - - 5.5 19.5 - - 10.4 24.5 - -
 8–11 32.7 55.3 - - 32.2 54.3 - - 40.7 56.0 - -
 LBW <8 years 7.1 8.3 1.2 (0.6;1.9)a <0.001 7.7 9.0 1.1 (0.7;1.5)a <0.001 10.0 9.7 −0.2 (−1.1;0.7) <0.001
 LBW ≥12 5.4 7.5 3.2 (1.3;5.0)a <0.001 5.1 7.3 1.3 (0.6;2)a <0.001 5.7 7.2 1.5 (1.0;2.1)a <0.001
 LBW 8-11 5.7 7.2 1.6 (1.3;2.0)a <0.001 6.2 7.5 1.4 (0.7;2.2)a <0.001 7.9 8.0 0.1 (−1.3;1.5) <0.001
Prenatal care (no. of visits)
 None 11.1 4.1 - - 9.7 4.7 - - 6.6 1.7 - -
 ≤6 or 35.5 49.9 - - 37.5 46.9 - - 35.1 24.2 - -
 ≥7 53.4 46.0 - - 52.8 48.4 - - 58.3 74.1 - -
 LBW None 10.1 13.9 2.7 (−0.2;5.6) <0.001 11.3 13.2 1.5 (−0.5;3.6) <0.001 16.9 24.2 3.7 (2.7;4.7)a <0.001
 LBW ≤6 or 7.5 9.3 1.3 (0.9;1.8)a <0.001 8.4 9.8 1 (0.1;1.8)a <0.001 11.7 14.0 1.4 (0.4;2.3)a <0.001
 LBW ≥7 5.4 5.0 −0.4 (−0.8;0.1) 0.002 5.1 5.2 0.4 (−0.2;0.9) <0.001 6.1 5.8 −0.3 (−0.5;0.0)a <0.001
Gestational age (weeks)
 <37 4.9 10.8 - - 4.9 11.0 - - 6.5 8.7 - -
 ≥37 95.1 89.2 - - 95.1 89.0 - - 93.5 91.3 - -
 LBW <37 45.1 34.9 1.2 (−1.6;4) <0.001 48.1 39.4 −1.2 (−3.7;1.3) <0.001 59.3 52.5 −0.1 (−0.6;0.4) <0.001
 LBW ≥37 4.6 4.2 0.1 (−0.7;0.8) 0.937 4.8 3.7 −1.3 (−2.2;0.4)a <0.001 5.2 3.9 −2 (−2.7;1.3)a <0.001
Mode of delivery
 Caesarean section 34.5 51.2 - - 38.0 60.3 - - 47.3 53.1 - -
 Vaginal delivery 65.5 48.8 - - 62.0 39.7 - - 52.7 46.9 - -
 Caesarean section LBW 5.3 7.4 2.1 (1.4;2.8)a <0.001 5.8 7.1 1.2 (0.7;1.7)a <0.001 8.0 8.4 0.5 (−0.1;1.1) <0.001
 Vaginal delivery LBW 7.3 7.7 0.4 (0.0;0.9) <0.001 7.7 9.0 0.7 (0.4;1.1)a <0.001 9.6 7.8 −1.2 (−1.5;−0.9)a <0.001
  South Central West Brazil
Maternal age (years)
 10–17 years 9.4 6.7 - - 10.6 7.0 - - 10.1 8.1 - -
 ≥35 years 10.5 15.4 - - 5.9 12.3 - - 8.0 13.1 - -
 18-34 80.1 77.9 - - 83.5 80.6 - - 81.9 78.9 - -
 LBW 10–17 years 10.6 10.0 −0.3 (−1.1;0.5) 0.246 10.2 10.3 0.6 (0.1;1.0)a 0.001 11.0 10.8 −0.1 (−0.8;0.5)a 0.008
 LBW ≥35 years 9.2 8.8 −0.5 (−1;−0.1)a 0.010 8.9 8.6 0.3 (−0.3;0.8) 0.175 9.8 9.1 −0.4 (−0.6;−0.2) <0.001
 LBW 18–34 6.8 7.5 0.5 (0.0;1.1) <0.001 6.7 7.7 0.9 (0.5;1.2)a <0.001 7.4 7.5 0.1 (−0.4;0.6) <0.001
Educational level (years)
 <8 years 46.2 20.6 - - 52.6 18.8 - - 55.4 22.3 - -
 ≥12 10.8 33 - - 7.4 27.0 - - 7.2 22.9 - -
 8–11 42.9 46.4 - - 40.1 54.2 - - 37.4 54.8 - -
 LBW <8 years 8.6 9.5 1 (0.4;1.6) <0.001 7.9 9.2 0.7 (0.2;1.2)a <0.001 8.4 9.3 0.6 (−1;2.2) ,0.001
 LBW ≥ 5.2 6.8 1.8 (0.7;2.9)a <0.001 5.7 7.8 1.8 (1.2;2.3)a <0.001 5.6 7.3 1.5 (1.1;1.9)a ,0.001
 LBW 8-11 6.6 7.8 1.1 (0.1;2.2)a <0.001 6.5 7.6 1.2 (0.7;1.6)a <0.001 6.9 7.8 0.9 (0.6;1.1)a <0.001
Prenatal care (no. of visits)
 None 4.4 1.4 - - 5.5 3.3 - - 8.3 3.0 - -
 ≤6 or UD 32.5 17.7 - - 40.1 27.6 - - 35.8 33.5 - -
 ≥7 63.2 80.9 - - 54.5 69.2 - - 55.9 63.5 - -
 LBW None 16.5 24.6 3.1 (1.4;4.8)a <0.001 13.5 16.9 1.3 (−1.4;4.1) <0.001 12.9 17.4 2.4 (0.6;4.1)a <0.001
 LBW ≤6 or UD 9.7 15.3 3.2 (2.4;4.0)a <0.001 8.2 12.3 2.6 (2.1;3.1)a <0.001 9.3 11.5 1.3 (0.2;2.4)a <0.001
 LBW ≥7 5.5 5.9 0.4 (−0.1;0.8) 0.011 5.9 5.7 0.3 (−0.2;0.8) 0.004 5.8 5.6 −0.1 (−0.3;0.0) 0.002
Gestational age (weeks)
 <37 5.5 8.2 - - 3.9 9.7 - - 5.2 9.6 - -
 ≥37 94.5 91.8 - - 96.1 90.3 - - 94.8 90.4 - -
LBW <37 63.1 57.4 −0.5 (−0.8;−0.2) <0.001 62.1 44.9 0 (−1.7;1.8) 0.019 56.1 46.1 −1 (−2.3;0.3) <0.001
 LBW ≥37 4.1 3.4 −1.4 (−1.8;−0.9)a <0.001 4.9 4.0 −0.7 (−2.7;1.3) <0.001 4.9 3.9 −1.6 (−2.1;−1.1)a <0.001
Mode of delivery
 Caesarean section 44.2 56.6 - - 49.2 59.5 - - 42.9 55.2 - -
 Vaginal delivery 55.8 43.4 - - 50.8 40.5 - - 57.1 44.8 - -
 Caesarean section LBW 7.3 8.4 0.5 (0.0;1.1)a <0.001 6.3 8.0 1.6 (1.2;2.0)a <0.001 7.1 8.0 1 (0.6;1.4)a <0.001
 Vaginal delivery LBW 7.5 7.1 −0.2 (−0.6;0.2) 0.078 8.1 8.0 0 (−0.4;0.5) 0.929 8.6 8.0 −0.5 (−1.1;0.2) <0.001
  1. aAAPC average annual percentage of change