Causes of Delivery and Outcomes of Very Preterm Twins Stratified to Zygosity

Abstract

The increasing rates of preterm birth among twins implicate that solid data on associated risks and outcomes are required. Assessment of zygosity is often based on clinical criteria (evaluation of placenta; same gender, birth weight discordance as surrogate criteria for monochorionic/monozygotic twins). The aim of this study was to compare clinical versus genetic assessment of zygosity and to compare causes of preterm delivery as well as outcome data of very-low-birth-weight (VLBW; birth weight <1,500 g) twins stratified to zygosity. In a multicenter study, we selected n = 176 sets of same gender twins and determined zygosity genetically. In a subgroup of 123 sets of twins, the attending physicians at the study centers were asked to document the parameter 'zygosity' (monozygotic/dizygotic) on the basis of their clinical judgment. Concordance between genetic and clinical assessment was 62.7% for monozygotic twins and 88.9% for dizygotic twins, respectively. Outcome parameters (death, BPD, ROP, NEC, IVH) were comparable in both groups. Genetically dizygotic twins were significantly more often born due to intrauterine infection (33% vs. 20% in monozygotic twins, p < .01) and antenatal antibiotics were more frequently given to mothers of dizygotic twins (62% vs. 47% in monozygotic twins, p < .01). Obstetric complications such as twintwin-transfusion-syndrome were only seen in monozygotic twins as expected. The unexpected increase of antenatal antibiotic treatment and birth due to intrauterine infection in dizygotic twins should be confirmed in additional VLBW twin-cohorts.

Cord blood hematopoietic cells from preterm infants display altered DNA methylation patterns

“…This raises the concern that multiplicity in the preterm subjects may have confounded our results. There is limited information on how the immune system differs with multiple births: it has been shown that intrauterine infection occurs more often in preterm births with dizygotic twins compared to monozygotic twins or singletons, but no differences in postnatal outcome have been associated with zygosity [52]. Additionally, CD4 + T cell activity has been observed to be significantly lower in preterm dizygotic twins than in preterm singletons [53].…”

Antenatal detection of chromosomal abnormalities combining QF-PCR and cytogenetic analysis

“…Furthermore, monozygotic twins are even more frequently associated with complications, mainly because of twin-twintransfusion-syndrome (TTTS) appearance, while a higher rate of intrauterine infections have been observed among dizygotic pregnancies. 33 The incidence of twining has been estimated to approximately 1 in 65 live births, with the proportion of dizygotic twins being settled to 70%, and monozygotic to 30%. 34 Assessment of zygosity is routinely based on sonographic identification of chorionicity and fetal gender determination, while in cases when the invasive procedure was conducted, a genetic determination using STR markers could be performed.…”

Altered Intracellular ATP Production by Activated CD4+ T-Cells in Very Preterm Infants

“…Our hypothesis is in accordance with previous studies that documented higher levels of Th2-cytokines in the blood of mothers carrying twins compared with singleton pregnancies [24] underlining the more profound Th1-Th2 shift that occurs in twin pregnancies. Moreover, a recent study demonstrated that both dizygotic twins and their mothers are more prone to infection than monozygotic twins, singletons, and their mothers [25]. …”