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Table 2 Contribution of temporal trends in pre-existing and gestational comorbidities on perinatal outcomes

From: Age-period-cohort effects in pre-existing and pregnancy-associated diseases amongst primiparous women

Perinatal outcomeRate per 100 birthsRelative change (2004 vs. 2014)
2004 (n = 1,121,535)2014 (n = 1,244,642)Rate difference (95% CI)Rate ratio (95% CI)Percent change
Small for gestational age
 Crude
 Adjusted for demographic variablesa
 Adjusted for demographic variablesa and comorbiditiesb
 Incremental effect of comorbiditiesb
113.35
110.59
101.26
123.65
124.77
124.95
10.30 (9.48–11.13)
14.18 (13.36–15.01)
23.69 (22.88–24.50)
1.09 (1.08–1.10)
1.13 (1.12–1.14)
1.23 (1.22–1.25)
0.10 (0.10–0.11)
9.09
12.83
23.40
10.57
Large for gestational age
 Crude
 Adjusted for demographic variablesa
 Adjusted for demographic variablesa and comorbiditiesb
 Incremental effect of comorbiditiesb
71.47
72.68
78.74
72.02
71.46
71.82
0.54 (− 0.12, 1.20)
− 1.23 (−  1.89, −  0.57)
− 6.92 (− 7.60, −  6.25)
1.01 (1.00–1.02)
0.98 (0.97–0.99)
0.91 (0.90–0.93)
−  0.07 (−  0.07, −  0.06)
0.76
−  1.69
−  8.79
−  7.10
Preterm birth
 Crude
 Adjusted for demographic variablesa
 Adjusted for demographic variablesa and comorbiditiesb
 Incremental effect of comorbiditiesb
86.47
83.80
84.72
89.06
88.70
88.46
2.59 (1.87–3.31)
4.90 (4.18–5.62)
3.73 (3.02–4.45)
1.01 (1.02–1.04)
1.06 (1.05–1.07)
1.04 (1.03–1.06)
−  0.02 (−  0.02, −  0.01)
2.99
5.85
4.41
−  1.44
  1. aDemographic variables include maternal age, maternal race, maternal education, marital status, smoking status, and gestational weight gain
  2. bComorbidities include chronic hypertension, pregnancy associated hypertension, eclampsia, pre-existing diabetes, and gestational diabetes