Increase in short telomeres during the third trimester in human placenta

Abstract

An increase in telomere shortening in gestational tissues has been proposed as a mechanism involved in the timing for the initiation of parturition. An increase in very short telomeres with increasing gestational age has been observed in mice; this study sought to explore this phenomenon in human pregnancies. Specifically, this study addressed the hypothesis that prior to labor, the quantity of very short telomeres (<3 kilobase (kb) lengths) increases in human placental tissue as term gestation approaches. The primary outcome was the quantity of very short telomeres present in placental tissue. Quantitative measurements of very short telomeres were performed using real-time polymerase chain reaction (qPCR) adaptation of the telomere restriction fragment technique. Placental tissue from 69 pregnant individuals were included. Mean gestational age was 39.1 weeks (term) and 36.2 weeks (preterm). For term versus preterm placentas, the observed increase in very short telomeres were as follows: 500 bp telomeres increased by 1.67-fold (p < 0.03); 1 kb telomeres increased 1.67-fold (p < 0.08); and 3 kb telomeres increased 5.20-fold (p < 0.001). This study confirms a significant increase in very short telomeres in human placental tissue at term; thereby supporting the hypothesis that telomere shortening at term contributes to the mechanism that determine the length of pregnancy thereby leading to onset of parturition.

Fig 1. Relative telomere quantity in preterm versus term human placental tissue by telomere lengths.

Relative quantity of very short telomeres (VST), stratified by telomere length, preterm group serves as reference for Pfaffl calculation. Data in mean ± S.D. (standard deviation), N = 11 for preterm and N = 58 for term samples. (·) indicates p < 0.05 comparing term to preterm.