Early demise of twins in a cohort of stillbirths and second trimester miscarriages

Abstract

Twins, particularly monochorionic (MC) pairs, are at increased risk for fetal death. Whereas previous work has sought to understand the mechanisms for this increased mortality, most studies analyze viable twin pregnancies or liveborn twin cohorts. In the Wisconsin Stillbirth Service Program cohort of 3,137 stillbirths and second trimester miscarriages, we identified 175 twin pregnancies for a twinning rate of 56/1,000, which is approximately double the general population. The excess of twins among miscarriages and stillbirths was attributable to MC pairs as the incidence of dizygotic (DZ) twinning was not increased compared to livebirth data. The leading causes of fetal demise among twins were twin-twin transfusion, acardia, and twin-twin disruption. Maternal causes of death, primarily premature rupture of membranes, were moderately increased in both MC and DZ twins relative to singletons. Although deceased twins were smaller than expected for viable twins at comparable gestational ages, placenta weights of deceased MC pairs were large compared to combined fetal weight, which indicates placental inefficiency likely due to vascular shunting. Co-twin survival was much lower for MC than for DZ pairs. Therefore, earlier diagnosis and treatment of MC twinning complications may decrease prenatal mortality. K E Y W O R D S fetal demise, miscarriage, stillbirth, twin-twin transfusion

3137 fetuses in 33 years: What we have learned from the Wisconsin stillbirth service program

“…In the group with hydrops, placentas were at the extremes of weight with 57% below the 10th centile, 34% above the 90th centile, and only 9% between the 10th and 90th centiles (McPherson, 2019). Among twins, even though the combined weight of deceased twin fetuses was usually less than expected for liveborn twins at the same gestational age, the placentas were large compared with fetal weight suggesting placental inefficiency (Korlesky & McPherson, 2019).…”

“…Among specific etiologies for hydrops, the most frequent was chromosomal followed by other syndromes, most notably lethal multiple pterygium/akinesia, which accounted for 6% of all hydrops (McPherson, 2019). There were rate of 56/1000, which is about double the rate of twinning in the general population (Korlesky & McPherson, 2019). Although maternal causes of stillbirth such as preterm premature rupture of membranes were increased in both monozygotic (MZ) and dizygotic (DZ) pairs, the incidence of DZ twinning was similar to that in livebirths while the excess of twins in the WiSSP cohort was entirely attributable to monochorionic (MC) pairs.…”

Monochorionic twins after in‐vitro fertilization: do they have poorer outcomes?

“…As our study included patients with ongoing MCDA twins in the first trimester, the miscarriages reported in our series occurred in the second trimester. Also, the few other studies that compared outcomes from the first trimester onwards did not distinguish between spontaneous miscarriage and intrauterine death 16,28 , whereas most deaths prior to 24 weeks are related to TTTS 17,20,35 . In the only prospective cohort study that evaluated separately miscarriage and fetal demise, Sperling et al 15 .…”

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“…Monochorionicity places two-thirds of MZ twins at increased risk for fetal death. According to researchers at the University of Wisconsin, the most common causes of death among this subset of MZ twin pairs include twin-to-twin transfusion syndrome, acardia and twin-twin disruption (Korlesky & McPherson, 2019). Using the 3137 records from the Wisconsin Stillbirth Program, gathered between 1983 and 2017, 175 relevant twin pregnancies were identified.…”