Zygosity as a Risk Factor for Complications and Outcomes of Twin Pregnancy

Abstract

All of the recorded twin live births in Washington State birth certificates between 1984 and 1988 were used a retrospective cohort study to determine the risk of zygosity on pregnancy complications and birth outcomes (n = 3458). Relative risks comparing different sex (DS) twins to same sex (SS) twins were corrected to relative risks relating dizygotic (DZ) to monozygotic (MZ) twins, using the Weinberg rule. A higher proportion of DS twin pregnancies (3.5%) than SS pregnancies (1.6%) were complicated by gestational diabetes, resulting in an estimated risk for DZ twin pregnancies relative to MZ pregnancies of 8.6 (95% CI = 3.5-21.0). DZ twin pregnancies were at a lower risk for complications of polyhydraminios (RRDZ∣MZ = 0.2, 95% CI = 0.1-0.4) and of pyelonephritis, (RRDZ∣MZ = 0.3, 95% 0 = 0.1-0.8). MZ twins were more likely to have low birthweight and to have shorter gestations. The proportion of first-born babies of MZ twin pairs who died during their first year was similar to that of first twins of DZ pairs; however, the second-born of MZ twins were more likely to die in infancy than were second-born DZ pairs. First twins of DZ pairs were more likely to die of SIDS (sudden infant death syndrome) than the first of MZ twins (RRDZ∣MZ = 1.5, 95% CI = 0.4-5.1). In contrast, DZ second-born were less likely to die of SIDS than were MZ second-born twins (RRDZ∣MZ = 0.1, 95%CI = 0.1-0.7). DZ twins were less likely to have adverse newborn conditions or malformations. The high risk for gestational diabetes for DZ twin mothers is possibly due to the presence of two placentas which may support the development of greater insulin antagonism than the single placenta in the mother of MZ twins. The reduced risk of DZ relative to MZ twins for selected adverse birth outcomes may result from the increased tendency of MZ twins to be premature.

Outcomes of singleton and twin pregnancies complicated by pre‐existing diabetes and gestational diabetes: A population‐based study in Alberta, Canada, 2005–11

“…A study on triplet pregnancies showed that the incidence of GDM was significantly higher in the triplet group than in the group that had undergone elective fetal reduction to twins . In addition, another study showed that dizygotic twin pregnancies (two placentas) were more likely to be complicated by GDM than monozygotic twin pregnancies (single placenta) …”

“…12 In addition, another study showed that dizygotic twin pregnancies (two placentas) were more likely to be complicated by GDM than monozygotic twin pregnancies (single placenta). 30 Women with diabetes during pregnancy and their babies are at increased risk of adverse pregnancy outcomes; in particular, pregnancies complicated by pre-DM are at higher risk than those complicated by GDM. This may be related to the effect of prolonged fetal exposure to the hyperglycemic milieu in pre-DM than GDM.…”

Predictors of adverse perinatal outcome in twins delivered at < 37 weeks

“…Several studies have identified inter-twin weight discordance and chorionicity as the most important prognosticators of perinatal outcome in twins [1][2][3][4][5][6][7]10 . A recent study 14 also suggested that neonatal mortality rate is also higher among pairs of twins in which the smaller twin weighs 5 10th percentile.…”

“…Two factors have been consistently associated with fetal and neonatal complications in twins: birth weight discordance and monochorionicity. Prematurity and associated morbidity seems to mediate both the effect of birth weight discordance 1,2-4 and chorionicity 2,[5][6][7] .…”

Epidemiology of gestational diabetes mellitus and its association with Type 2 diabetes

“…In an interesting study of the prevalence of GDM in dizygotic (DZ) twin pregnancies with two placentas compared with monozygotic (MZ) twin pregnancies with one placenta, Hoskins et al . [36] found that a higher proportion of different‐sex rather than same‐sex twin pregnancies was complicated by GDM (3.5% vs. 1.6%).…”