Biodemographic Analysis of Factors Related to Perinatal Mortality in Portugal (1988–2011)
Table 3
(a) 1988–95 and 2010-11 forward (Wald) binary logistic regression parameters. Dependent variable: stillbirths (≥500 grams regardless of duration of gestation). (b) 1988–95 and 2010-11 forward (Wald) binary logistic regression parameters. Dependent variable: stillbirths (duration of gestations ≥22 weeks).
(a)
Covariable
df
With multiple
Only single
Wald
OR
Wald
OR
Multiple (S)
1
51
0.755
—
—
—
Sex (female)
1
43
1.126
41
1.127
BW (2500–4000)
3
58051
57026
>4000
1
206
1.933
189
1.897
1500–2499
1
15189
16.626
14839
16.857
<1500
1
56348
212.788
55134
217.684
Mat. age (<20)
3
2949
2804
20–29
1
92
1.482
86
1.472
30–39
1
993
3.711
966
3.734
40–49
1
8
1.155
12
1.206
Year (1988)
1
3223
0.922
2884
0.925
Nagelkerke
0.312
0.309
In parentheses the reference category (S: single; BW: birth weight; weeks: duration of gestation). df = degrees of freedom; = statistical significance < 0.01. OR = relative risk. Wald values taken to the nearest integer. Nagelkerke corrected for total and single deliveries.
(b)
Covariable
df
With multiple
Only single
Wald
OR
Wald
OR
Multiple (S)
1
4
0.891
—
—
—
Sex (female)
1
4
1.055
5
1.058
BW (2500–4000)
3
6715
6379
>4000
1
208
2.272
190
2.227
1500–2499
1
4091
9.493
3972
9.576
<1500
1
5880
45.880
5463
44.503
Mat. age (<20)
3
584
538
20–29
1
11
1.171
12
1.177
30–39
1
197
2.058
188
2.058
40–49
1
28
0.679
25
0.686
Weeks (37–41)
3
2102
2130
>41
1
157
2.745
162
2.807
32–36
1
1401
3.553
1412
3.673
22–31
1
1656
7.664
1669
8.250
Parity (>1)
1
3
ns
1.048
4
ns
1.056
Year (1988)
1
897
0.934
760
0.937
Nagelkerke
0.326
0.323
In parentheses the reference category (S: single; BW: birth weight; weeks: duration of gestation). df = degrees of freedom; = statistical significance < 0.05, < 0.01, ns nonsignificant. OR = relative risk. Wald values taken to the nearest integer. Nagelkerke corrected for total and single deliveries.
