Table 4.

Associations between linkage accuracy (using the bespoke algorithm) and characteristics of the cohort

	True matches N = 123 n (%)	Missed-matches N = 68 n (%)	OR (95% CI)	p-value	False-matches N = 8 n (%)	OR (95% CI)	p-value
Age of the mother in years
< 20	25 (20.3)	19 (27.9)	1	p = 0.047	-		p = 0.095
20–35	67 (54.5)	30 (44.1)	1.7 (0.8–3.5)		8 (100)
> 35	22 (17.9)	7 (10.3)	2.3 (0.8–6.7)		-
Missing	9 (7.3)	12 (17.5)			-
Maternal literacy
Illiterate	7 (5.7)	5 (7.3)	1	p = 0.113	-	1	p = 0.617
1–3 years	8 (6.5)	4 (5.9)	1.4 (0.3–7.5)		1 (12.5)	0.9 (0.4–1.9)a
4–7 years	32 (26.0)	14 (20.6)	1.6 (0.4–6.0)		2 (25.0)
> 8 years	34 (27.6)	20 (29.4)	1.2 (0.3–4.3)		4 (50.0)
> 11 years	19 (15.4)	3 (4.4)	4.5 (0.8–24.1)		-
Missing	23 (18.7)	22 (32.3)			1 (12.5)
Previous fetal death or abortion
No	36 (29.3)	17 (25.0)	1	p = 0.574	2 (25.0)	1	p = 0.966
Yes	59 (48.0)	31 (45.6)	0.9 (0.4–1.8)		4 (50.0)	1.2 (0.2–7)a
Missing	28 (22.7)	20 (29.4)			2 (25.0)
Gestational age
< 22 weeks	9 (7.3)	2 (2.9)	1	p = 0.248	-		p = 0.492
22–27 weeks	29 (23.6)	18 (26.5)	0.3 (0.1–1.8)		3 (37.5)	1
28–31 weeks	21 (17.8)	11 (16.2)	0.4 (0.1–2.3)		3 (37.5)	0.7 (0.4–1.3)a
32–36 weeks	26 (21.1)	19 (27.9)	0.3 (0.1–1.5)		2 (25.0)
37–41 weeks	28 (22.8)	9 (13.2)	0.7 (0.1–3.8)		-
≥ 42 weeks	2 (1.6)	-			-
Missing	8 (6.5)	9 (13.2)			-
Birth or death weight
≥ 2500	23 (18.7)	16 (23.5)	1	p = 0.798	-		p = 0.165
1500–2500	26 (21.2)	16 (23.5)	1.1 (0.4–2.7)		-
< 1500	64 (52.0)	31 (45.6)	1.4 (0.6–3.0)		7 (87.5)
Missing	10 (8.1)	7 (7.3)			1 (12.5)

^aDue to the small number of observations, we used only two categories, the first category without missing value as the reference one