Table 3. Univariate GLMM analysis of potential risk factors for stillbirth of 568 piglets born from 45 Landrace × Yorkshire sows on a farm in Vietnam.

Covariates	Stillbirth rate	CI; 95% CI; P
P = 2−4	9.0 (25/279)	1
P = 1	13.8 (23/167)	1.96; 0.61−6.29; 0.256
P = 5−8	27.0 (33/122)	4.38; 1.27−15.10; 0.019
GL = 114−116 days	9.4 (38/404)	1
GL = 117−118 days	12.3 (7/57)	1.41; 0.28−7.12; 0.677
GL = 112−113 days	33.6 (36/107)	5.98; 1.92−18.62; 0.002
LS = 5−13	6.3 (12/189)	1
LS = 14−20	18.2 (69/379)	3.76; 1.23−11.44; 0.020
BO = 2−5	9.6 (17/178)	1
BO = 6−10	12.4 (26/210)	1.41; 0.68− 2.95; 0.356
BO >10	21.1 (38/180)	2.94; 1.42−6.09; 0.004
M	14.8 (42/283)	1
F	13.7 (39/285)	094; 0.54−1.63; 0.831
BI < 30 min	11.5 (56/489)	1
BI >30 min	31.6 (25/79)	3.05; 1.50−6.19; 0.002
CFD < 90 min	7.8 (22/282)	1
CFD = 90−240 min	15.9 (37/232)	2.53; 1.32−4.85; 0.005
CFD > 240 min	40.7 (22/54)	4.89; 1.92−12.45; < 0.001
CRL = 25−29 cm	9.5 (23/242)	1
CRL > 29 cm	18.7 (45/241)	1.53; 0.72−3.23; 0.267
CRL < 25 cm	15.3 (13/85)	2.34; 0.94−5.81;0.066
BW = 1.0−1.8 kg	9.2 (32/349)	1
BW >1.8 kg	22.3 (25/112)	1.71; 0.77−3.79; 0.184
BW < 1.0 kg	22.4 (24/107)	4.29; 2.06−8.96; < 0.001
BMI > 16	18.2 (36/198)	1
BMI < 16	12.2 (45/370)	0.35; 0.18−0.68; 0.002
PI < 50	30.3 (33/109)	1
PI > 50	14.3 (81/568)	0.22; 0.11−0.44; < 0.001

P: Parity, GL: Gestation length, LS: Litter size, BO: Birth order, CRL: Crown-rump length, BW: Birth weight, BMI: Body mass index, PI: Ponderal index, BI: Birth interval, CFD: Cumulative farrowing duration, M: Male, FM: Female. CI: Confidence interval.