Despite its high prevalence and the possible link with perinatal complications, marginal
cord insertion (MCI) is surrounded by considerable controversy regarding management.
Our aim through this meta-analysis was to study its association with several perinatal
outcomes in a manner that provides trustworthy and exact effect measures, enabling
us eventually to evaluate its overall risk for pregnancy.
A systematic search was performed in Medline, Scopus, and the Cochrane Library as
of 30th July 2022 to identify eligible studies.
Study eligibility criteria
Observational studies including singleton pregnancies and comparing MCI to central/eccentric
cord insertion (CCI), either prenatally or postnatally identified, were considered
Study appraisal and synthesis methods
The Newcastle-Ottawa scale was used to assess study quality, and the QUIPS tool was
used to assess bias risk. The main outcome was small for gestational age (SGA) neonates.
Q test and an I2 score were used to assess study heterogeneity. The analyses were carried out using
random-effects model, and the results were expressed as relative risk or mean difference
with a 95% confidence interval.
In total, 15 studies (13 cohort studies and two case-control studies) contributed
data to the analysis. In seven of these, there was a prenatal and in eight a postnatal
diagnosis. The overall prevalence of MCI was 6.15% (1.13-11.3%). MCI pregnancies compared
to CCI ones were found to be at higher risk of SGA neonates (RR: 1.25; 95% CI:1.21-1.29),
preeclampsia (RR: 1.61; 95% CI:1.54-1.67), placental abruption (RR: 1.53; 95% CI:1.34-1.75),
stillbirth (RR: 1.97; 95% CI:1.02-3.78), preterm delivery (RR: 1.47; 95% CI:1.24-1.75),
lower mean gestational age at birth (MD: -0.20; 95% CI: -0.38 to -0.01), emergency
cesarean delivery (RR: 1.39; 95% CI:1.35-1.44), lower mean birthweight (MD: -139.19;
95% CI: -185.78 to -92.61), 5-minute Apgar score <7 (RR: 1.48; 95% CI:1.00-2.19) and
neonatal intensive care unit admission (RR: 1.57; 95% CI:1.20-2.06). When only prenatally
diagnosed MCI pregnancies were considered, the risk remained high regarding SGA (RR:
1.34; 95% CI:1.21-1.48), preeclampsia (RR: 1.42; 95% CI:1.01-1.99), stillbirth (RR:
2.99; 95% CI:1.03-8.70), preterm delivery (RR: 1.41; 95% CI:1.19-1.68), lower mean
gestational age at birth (MD: -0.22; 95% CI: -0.33 to -0.11) and lower mean birthweight
(MD: -122.41; 95% CI: -166.10 to -78.73).
Through this analysis the higher risk that MCI poses for pregnancy, regarding several
adverse outcomes, became evident. Many of these associations persisted among the prenatally
diagnosed pregnancies. The underlining pathophysiology should be investigated and
further research is needed on the effect of increased surveillance in improving perinatal