Association between placental location and cord insertion site with pre-eclampsia: a retrospective cohort study

Figures & data

Figure 1. Flow diagram of the study.

Table 1. Baseline characteristics according to placental location.

	Anterior	Posterior	p Value
	n = 1133	n = 1086
Maternal age (years), mean ± SD	33.78 ± 4.00	33.66 ± 3.81	.873
Pre-pregnancy BMI (kg/m^2), mean ± SD	21.49 ± 3.28	21.12 ± 3.05	.012*
Smoking	8 (0.71%)	4 (0.37%)	.278
In vitro fertilization	142 (12.53%)	110 (10.13%)	.074
Overt diabetes mellitus	12 (1.06%)	9 (0.83%)	.575
Chronic hypertension	7 (0.62%)	6 (0.55%)	.84
Rheumatologic disease^a	10 (0.88%)	10 (0.92%)	.924
Kidney disease^b	4 (0.35%)	4 (0.37%)	1
Hematologic disease^c	4 (0.35%)	5 (0.46%)	.749
Cord insertion site			.568
Central	1072 (94.62%)	1038 (95.58%)
Marginal	54 (4.77%)	42 (3.87%)
Velamentous	7 (0.62%)	6 (0.55%)

BMI: body mass index; SD: standard deviation. *p < .05 was considered statistically significant.

^aRheumatologic disease, including systemic lupus erythematosus and antiphospholipid syndrome.

^bKidney disease, including chronic kidney disease, IgA nephropathy, and glomerulonephritis.

^cHematologic disease, including aplastic anemia, immune thrombocytopenia, and chronic myeloid leukemia.

Table 2. Pregnancy and neonatal outcomes according to placental location.

	Anterior	Posterior	p Value
	n = 1133	n = 1086
Gestational age (weeks), mean ± SD	38.0 ± 2.25	38.1 ± 2.40	.326
Mode of delivery
Vaginal	714 (63.0%)	697 (64.2%)	.57
Cesarean section	419 (37.0%)	389 (35.8%)
Fetal presentation			.67
Cephalic	1028 (90.7%)	996 (91.7%)
Breech	102 (9.00%)	88 (8.10%)
Transverse	3 (0.26%)	2 (0.18%)
Birth weight (g), mean ± SD	2973.3 ± 554.7	2982.5 ± 561.8	.842
Placenta weight (g), mean ± SD	649.6 ± 139.2	660.6 ± 142.3	.115
Pregnancy-induced hypertension	14 (1.24%)	6 (0.55%)	.089
Pre-eclampsia	93 (8.21%)	33 (3.04%)	<.0001*
Placenta abruption	8 (0.71%)	2 (0.18%)	.109
PPROM	52 (4.59%)	41 (3.78%)	.339
Spontaneous preterm delivery	24 (2.12%)	29 (2.67%)	.395
GDM	77 (6.80%)	71 (6.54%)	.807
Postpartum hemorrhage	53 (4.68%)	41 (3.78%)	.291
Apgar score <7 at 5 min	52 (4.59%)	64 (5.90%)	.168
NICU admission	215 (19.0%)	205 (18.9%)	.953
RDS	58 (5.12%)	67 (6.17%)	.283
Ventilator	66 (5.83%)	78 (7.18%)	.195
SGA	50 (4.41%)	48 (4.42%)	.994
Sex (female)	588 (51.9%)	556 (51.2%)	.742

SD: standard deviation; PPROM: preterm premature rupture of membrane; GDM: gestational diabetes mellitus; NICU: neonatal intensive care unit; RDS: respiratory distress syndrome; SGA: small for gestational age. *p < .05 was considered statistically significant.

Table 3. Univariate and multivariate logistic regression for prediction of pre-eclampsia.

	Univariate analysis			Multivariate analysis (Model I)			Multivariate analysis (Model II)
	OR	95% CI	p Value	OR	95% CI	p Value	OR	95% CI	p Value
Maternal age	1.08	(1.03–1.13)	.002*	1.05	(1.0–1.10)	.06	1.05	(1.00–1.10)	.07
Pre-pregnancy BMI	1.19	(1.13–1.24)	<.0001*	1.15	(1.10–1.21)	<.0001*	1.15	(1.09–1.21)	<.0001*
Smoking (yes vs. no)	1.53	(0.20–12.0)	.68
In vitro fertilization (yes vs. no)	2.13	(1.33–3.41)	.002*	1.86	(1.11–3.11)	.019*	1.76	(1.04–3.00)	.036*
Overt DM (yes vs. no)	5.44	(1.96–15.12)	.001*	2.26	(0.71–7.24)	.17	2.34	(0.71–7.74)	.16
Chronic hypertension (yes vs. no)	10.90	(3.52–34.0)	<.0001*	5.76	(1.63–20.36)	.007*	6.70	(1.77–25.32)	.005*
Rheumatologic disease (yes vs. no)	2.00	(0.46–8.74)	.36
Kidney disease (yes vs. no)	10.33	(0.02–0.41)	.002*	10.50	(2.25–49.09)	.003*	12.20	(2.28–65.4)	.004*
Hematologic disease (yes vs. no)	5.69	(1.14–28.48)	.035*	4.89	(0.89–26.77)	.07	4.74	(0.82–27.43)	.08
Cord insertion (marginal vs. central)	3.32	(1.80–6.19)	.0002*				3.64	(1.90–6.97)	<.0001*
Cord insertion (velamentous vs. central)	<0.001	<0.001, >999.999	.98				<0.001	<0.001, >999.999	.98
Placental location (anterior vs. posterior)	3.05	(1.99–4.68)	<.0001*				3.05	(1.95–4.77)	<.0001*

OR: odds ratio; CI: confidence interval; BMI: body mass index; DM: diabetes mellitus. *p < .05 was considered statistically significant.

Model I: adjusted for maternal age, pre-pregnancy BMI, history of smoking, in vitro fertilization, chronic hypertension, overt diabetes mellitus, kidney, rheumatologic, and hematologic disorders.

Model II: Model I + adjusted for cord insertion and placental location.

Figure 2. Receiver operating characteristic (ROC) curves for prediction of pre-eclampsia of the two models.

Comparison of area under ROC curves of two models showed that the addition of placental location and cord insertion site improved its predictive performance: 0.749 (95% CI 0.70–0.79) vs. 0.700 (95% CI 0.65–0.75), p = .02.