The impact of lateral placenta on preeclampsia and small for gestational age neonates: a systematic review and meta-analysis

Objectives We conducted a systematic review and meta-analysis to quantitatively summarize the present data on the association of prenatally identified lateral placenta in singleton pregnancies with small for gestational age (SGA) neonates, preeclampsia and other perinatal outcomes. Methods From inception to November 2021, we searched PubMed/Medline, Scopus and The Cochrane Library for papers comparing the risk of SGA and preeclampsia, as well as other perinatal outcomes in singleton pregnancies with a prenatally identified lateral placenta to those with non-lateral placentas. The revised Newcastle-Ottawa Scale was used to evaluate the quality of eligible papers. The I-2 test was employed to evaluate the heterogeneity of outcomes among the studies. To investigate the possibility of publication bias, funnel plots were constructed. Prospero RN: CRD42021251590. Results The search yielded 5,420 articles, of which 16 were chosen, comprising of 15 cohort studies and one case control study with a total of 4,947 cases of lateral and 96,035 of non-lateral placenta (controls) reported. SGA neonates were more likely to be delivered in cases with a lateral placenta (OR: 1.74; 95% CI: 1.54-1.96; p<0.00001; I-2=47%). Likewise, placental laterality was linked to a higher risk of fetal growth restriction (OR: 2.18; 95% CI: 1.54-3.06; p<0.00001; I2=0%), hypertensive disorders of pregnancy (OR: 2.39; 95% CI: 1.65-3.51; p=0.0001; I-2=80%), preeclampsia (OR: 2.92; 95% CI: 1.92-4.44; p<0.0001; I-2=82%) and preterm delivery (OR: 1.65; 95% CI: 1.46-1.87; p<0.00001; I-2=0%). Conclusions The prenatal diagnosis of a lateral placenta appears to be associated with a higher incidence of preeclampsia, fetal growth restriction, preterm delivery and SGA. This may prove useful in screening for these conditions at the second trimester anomaly scan.