Prevalence and association of placental lesions with obstetrical features and outcome: data from French prospective study

Since the Consensus Statement diffused by the Amsterdam Placental Workshop Group, knowledge of the meaning of placental vascular malperfusion has become essential in the unavoidable analysis of obstetrical history in a patient followed for autoimmune disease or any other maternal comorbidity. We aimed to analyse the prevalence of various placental lesions from a 6-months prospective observational study and to correlate the various placental profiles to obstetrical outcome, maternal diseases and pregnancy treatments. The frequency of foetal vascular malperfusion lesion could be estimated at 8.7%, in our population and to understand its neonatal associations. The study groups consisted of 208 consecutive women which ended the pregnancy and have placental analysis during the period of the study. From December 2015 to October 2017, from overall 4398 delivered pregnancies in university obstetrical department, 208 (4.7%) placental analysis have been done and included in the study. The placental analysis have been done for vascular obstetrical complications during the pregnancy (n = 106; 51%), unexplained abnormal foetal heart rate tracings (n = 59; 28,3%), suspicion of intra-amniotic infection (n = 12; 5,7%%), term new-borns Apgar score <7 or arterial cord blood pH ≤ 7 (n = 7; 3,5%), spontaneous preterm delivery (n = 19; 9,1%), intrahepatic cholestasis of pregnancy (n = 5; 2,4%). An adverse obstetrical event was noted in 87 cases (42%): preeclampsia or HELLP syndrome (n = 15; 7%), FGR (n = 59; 28%), gestational diabetes (n = 33; 16%) and gestational hypertension (n = 19; 9%). Placental histological analysis showed abnormal vascular features in 159 cases (76%), inflammatory features in 16 placentas (8%), vascular and inflammatory features in 10 cases (4%), chorioamnionitis in 38 cases (18%) and absence of any abnormality in 43 cases (21%). A cluster analysis of histological features allowed distinguishing three placental patterns: a normal pattern characterised by the absence of any placental lesions, an inflammatory pattern characterised by the presence of villitis and/or chronic intervillositis; a vascular pattern with the presence of thrombosis, maternal floor infarct with massive perivillous fibrin deposition, infarction and chronic villositis hypoxia. Women with inflammatory placental profile have significantly increased frequencies of tobacco use (50% vs. 9%; P = 0.03), pathological vascular Doppler (50% vs. 5%; P = 0.001), FGR (100% vs. 14%; P = 0.0001) and oligohydramnios (67% vs. 5%; P = 0.0001) than those with normal placentas. A higher rate of vascular or inflammatory lesion were observed in women with Hypertensive disorder of pregnancy, where as those with inflammatory pattern have significantly more frequent FGR (100% vs 34%; P = 0.02) and oligohydramnios (67% vs 5%; P = 0.0002). The placenta analysis is important to understand the origin of adverse obstetrical outcome and the risk for subsequent pregnancy.