Chronic Placental Inflammation in Twin Pregnancies

Abstract

Background: Chronic placental inflammation, such as villitis of unknown etiology (VUE) and chronic chorioamnionitis (CCA), is considered a placental manifestation of maternal anti-fetal rejection. The aim of this study is to investigate its frequency in twin pregnancies compared to singleton pregnancies.

Methods: Three hundred twin placentas and 1,270 singleton placentas were consecutively collected at a tertiary medical center in Seoul, Republic of Korea from 2009 to 2012. Hematoxylin and eosin sections of tissue samples (full-thickness placental disc and chorioamniotic membranes) were reviewed.

Results: Non-basal VUE was more frequent in twin placentas than in singleton placentas (6.0% vs 3.2%, p < .05). In preterm birth, CCA was found less frequently in twin placentas than in singleton placentas (9.6% vs 14.8%, p < .05), reaching its peak at an earlier gestational age in twin placentas (29-32 weeks) than in singleton placentas (33-36 weeks). CCA was more frequent in twin pregnancies with babies of a different sex than with those with the same sex (13.8% vs 6.9%, p=.052). Separate dichorionic diamniotic twin placentas were affected by chronic deciduitis more frequently than singleton placentas (16.9% vs 9.7%, p<.05).

Conclusions: The higher frequency of non-basal VUE in twin placentas and of CCA in twin placentas with different fetal sex supports the hypothesis that the underlying pathophysiological mechanism is maternal anti-fetal rejection related to increased fetal antigens in twin pregnancies. The peak of CCA at an earlier gestational age in twin placentas than in singleton placentas suggests that CCA is influenced by placental maturation.

Keywords: Inflammation; Placenta; Preterm birth; Twins.

Fig. 1.

The frequency of chronic placental inflammation in twin placentas. (A) The frequency of villitis of unknown etiology (VUE) is not statistically different between twin and singleton placentas. (B) Non-basal type of VUE is more frequent in twin placentas than in singleton placentas (^*p<.05), but basal type of VUE is not. (C, D) The frequencies of chronic chorioamnionitis (CCA) (C) and chronic deciduitis (CD) (D) are not statistically different between twin and singleton placentas.

Fig. 2.

The frequency of villitis of unknown etiology (VUE) in twin placentas according to the gestational age. (A) VUE in singleton and twin placentas is found more frequently as gestational age at birth increases. (B) Non-basal VUE is more frequent in twin placentas than in singleton placentas at term (^**p<.01). (C) There is no significant difference in the frequency of basal VUE between singleton and twin placentas. GAD, gestational age at delivery

Fig. 3.

The frequency of chronic chorioamnionitis (CCA) in twin placentas according to the gestational age. (A) CCA is less frequent in twin placentas than singleton placentas at preterm birth (^*p<.05). (B) CCA in twin placentas is decreased significantly compared with singleton placentas at 33–36 weeks of gestation (^*p<.05). Twin placentas are affected by CCA most frequently at 29–32 weeks, in contrast to singleton placentas at 33–36 weeks. GAD, gestational age at delivery

Fig. 4.

The frequency of chronic deciduitis (CD) in twin placentas at preterm and term birth. (A) CD is detected at similar frequencies between preterm and term placentas. (B) Separate dichorionic diamniotic (DiDiS) twin placentas are affected by CD more frequently than singleton placentas, especially at term (^**p<.01).

Fig. 5.

Association of villitis of unknown etiology (VUE) with intrauterine growth restriction (IUGR). (A) VUE is found more frequently in singleton placentas of IUGR cases than in those of non-IUGR cases (^***p<.001). (B) Non-basal VUE in singleton and twin placentas is more frequent in IUGR cases than in non-IUGR cases (singleton, ^***p<.001; twin, ^*p<.05). (C, D) The frequencies of chronic chorioamnionitis (C) and chronic deciduitis (D) are not associated with IUGR.

Fig. 6.

The frequency of chronic placental inflammation in spontaneous preterm birth and indicated preterm birth. (A) Villitis of unknown etiology (VUE) is more frequent in indicated preterm birth than in spontaneous birth of singleton placentas (^*p<.05). (B) Non-basal VUE is detected more frequently in indicated preterm birth than in spontaneous birth of singleton placentas as well as twin placentas (^*p<.05). (C, D) The frequencies of chronic chorioamnionitis (C) and chronic deciduitis (D) are not different between spontaneous and indicated preterm birth.