. Author manuscript; available in PMC: 2012 Sep 10.

Published in final edited form as: Paediatr Perinat Epidemiol. 2010 Jan;24(1):102–112. doi: 10.1111/j.1365-3016.2009.01087.x

Table 3.

Comparisons of birth record variables and the Pregnancy, Infection, and Nutrition (PIN) cohort study variables stratified by race, 2001–05

	White, non-Hispanic					Black, non-Hispanic
Maternal demographics and health behaviours – categorical
	Prevalence n (%)		n	% Agreement	Kappa [95% CI]	Prevalence n (%)		n	% Agreement	Kappa [95% CI]
	Birth records	PIN	n	% Agreement	Kappa [95% CI]	Birth records	PIN	n	% Agreement	Kappa [95% CI]
Marital status			1176	96.00%	0.83 [0.78, 0.88]			355	94.65%	0.88 [0.83, 0.93]
Married	1037 (88.0)	993 (84.4)				136 (38.2)	119 (33.5)
Not married	142 (12.0)	183 (15.6)				220 (61.8)	236 (66.5)
Alcohol			1059	99.62%				268	99.25%
Drink <5/week	1179 (100.0)	1055 (99.6)				356 (100.0)	266 (99.3)
Drink ≥5/week	0 (0.0)	4 (0.4)				0 (0.0)	2 (0.8)

Maternal demographics, health behaviours and previous pregnancies – continuous
	Mean (SD)		n	Spearman [95% CI]	CCC [95% CI]	Mean (SD)		n	Spearman [95% CI]	CCC [95% CI]
	Birth records	PIN	n	Spearman [95% CI]	CCC [95% CI]	Birth records	PIN	n	Spearman [95% CI]	CCC [95% CI]

Years of education	15.4 (2.1)	16.1 (2.9)	1176	0.92 [0.91, 0.94]	0.83 [0.82, 0.85]	13.2 (2.1)	13.3 (2.3)	352	0.90 [0.86, 0.94]	0.89 [0.87, 0.91]
Maternal age	30.7 (5.3)	30.0 (5.3)	1179	0.996 [0.99, 1.00]	0.99 [0.99, 0.99]	26.5 (5.6)	25.8 (5.6)	356	0.99 [0.98, 1.00]	0.98 [0.98, 0.99]
Maternal weight gain	33.3 (11.8)	34.8 (12.3)	1102	0.86 [0.83, 0.88]	0.85 [0.84, 0.87]	31.4 (15.3)	30.1 (15.3)	315	0.72 [0.65, 0.80]	0.72 [0.66, 0.77]
Number of cigarettes smoked	1.0 (3.8)	0.8 (3.0)	1057	0.80 [0.75, 0.86]	0.81 [0.79, 0.83]	1.1 (3.2)	0.6 (1.9)	267	0.81 [0.70, 0.91]	0.68 [0.61, 0.74]
Number of previous pregnancies	0.7 (0.9)	0.7 (0.9)	1146	0.98 [0.97, 0.99]	0.62 (0.60, 0.66]	0.9 (1.0)	1.0 (1.1)	344	0.96 [0.93, 0.98]	0.59 [0.53, 0.64]

Major pregnancy events – categorical
	Prevalence n (%)		n	% Agreement	Kappa [95% CI]	Prevalence n (%)		n	% Agreement	Kappa [95% CI]
	Birth records	PIN	n	% Agreement	Kappa [95% CI]	Birth records	PIN	n	% Agreement	Kappa [95% CI]

Birthweight (g)			1179	98.90%	0.92 [0.86, 0.96]			356	99.44%	0.98 [0.95, 1.00]
<1500	12 (1.0)	13 (1.1)				16 (4.5)	16 (4.5)
1500–2499	74 (6.3)	66 (5.6)				42 (11.8)	42 (11.8)
≥2500	1093 (92.7)	1100 (93.3)				298 (83.7)	298 (83.7)
Preterm			1179	98.30%	0.92 [0.88, 0.95]			356	96.63%	0.89 [0.83, 0.95]
Yes	131 (11.1)	135 (11.5)				72 (20.2)	70 (19.7)
No	1048 (88.9)	1044 (88.6)				284 (79.8)	286 (80.3)
Anaemia			1149	73.37%	0.17 [0.11, 0.22]			343	60.06%	0.19 [0.11, 0.26]
Any time	88 (7.5)	331 (28.8)				49 (13.8)	167 (48.7)
No anaemia	1091 (92.5)	818 (71.2)				307 (86.2)	176 (51.3)
GDM			1151	94.35%	0.06 [0.00, 0.16]			344	92.44%	0.15 [0.00, 0.34]
Yes	30 (2.5)	42 (3.7)				17 (4.8)	16 (4.7)
No	1149 (97.5)	1109 (96.4)				339 (95.2)	328 (95.4)
PIH/eclampsia			1123	95.01%	0.72 [0.66, 0.79]			334	93.71%	0.68 [0.55, 0.80]
Yes	105 (9.1)	122 (10.6)				35 (10.1)	40 (11.6)
No	1044 (90.9)	1029 (89.4)				311 (89.9)	304 (88.4)

Major pregnancy events – continuous
	Mean (SD)		n	Spearman [95% CI]	CCC [95% CI]	Mean (SD)		n	Spearman [95% CI]	CCC [95% CI]
	Birth records	PIN	n	Spearman [95% CI]	CCC [95% CI]	Birth records	PIN	n	Spearman [95% CI]	CCC [95% CI]

Gestation	38.55 (2.1)	38.9 (2.1)	1179	0.90 [0.89, 0.92]	0.95 [0.95, 0.96]	37.6 (3.2)	37.6 (3.1)	356	0.90 [0.87, 0.93]	0.97 [0.97, 0.98]
Birthweight	3349.0 (585.1)	3359.4 (582.8)	1175	0.99 [0.98, 0.99]	0.99 [0.99, 0.99]	3043.6 (724.9)	3047.9 (721.0)	354	0.98 [0.97, 1.00]	0.99 [0.99, 0.99]

CCC, concordance correlation coefficients; CI, confidence interval; GDM, gestational diabetes mellitus; PIH, pregnancy-induced hypertension.