Curves of Placental Weights of Live-Born Twins

First trimester maternal serum placental protein 13 levels in singleton vs. twin pregnancies with and without severe pre-eclampsia

“…Koster et al [20] reported a median of 1.53 MoM for mono-(n = 51) and 1.56 MoM for dichorionic (n = 241) twins using a dissociation-enhanced lanthanide fluorescent immunoassay (DELFIA) assay, thus, both platforms showed a large increase in PP13 among twins. Such a finding would be expected given the larger placental mass in twins [12], and the fact that PP13 is exclusively expressed in the placenta [3,31]. The 95% confidence interval for the twin median in our study, 1.42-2.12 MoM, is consistent with the approximately Table 2 Median placental protein 13 (PP13) levels in twins and singletons according to outcome.…”

“…The 95% confidence interval for the twin median in our study, 1.42-2.12 MoM, is consistent with the approximately Table 2 Median placental protein 13 (PP13) levels in twins and singletons according to outcome. doubling of feto-plancental markers [12], as found in twin studies of maternal serum pregnancy associated plasma protein A (PAPP-A), free beta subunit of human chorionic gonadotropin (fβ-hCG) and alpha feto protein (AFP) [22,23,30]. For un-conjungated estriol (uE 3 ), the median in twins has been estimated to be 1.68 MoM [10], but uE 3 is simultaneously produced by the placenta and in maternal adipose tissue, whereas PP13 is only expressed in the placenta [31].…”

The impact of chorionicity on maternal pregnancy outcomes

“…Gielen et al studied the placental weights of liveborn twins and created growth curves that showed that mean placental weights are very similar in twin pregnancies, particularly after 29 weeks. 25 Further supporting this hypothesis, two older studies concluded that chorionicity has no effect on placental weight. 26,27 There is also some question that immunologic factors may have a role in the pathogenesis of preeclampsia so that paternally derived genome may function differently based on zygosity; however, this remains controversial.…”

The potential impact of the fetal genotype on maternal blood pressure during pregnancy

“…In general, however, we hypothesized that one likely option would be via changes in placental function or secretion of vasoactive hormones and proteins [5] with the placenta largely being a fetal organ that expresses the fetal genotype [6], despite part of it being of maternal origin arising from the transformation of the uterine mucosa [7]. Relative to singleton pregnancies, twin pregnancies are associated with increased total placental weight, whether [8] or not [9] the twins share a placenta. In a large American study of 684 twin pregnancies and 2946 singleton pregnancies, the mean [95% confidence interval (95% CI)] relative risks for the development of both gestational hypertension [2.04 (1.60-2.59)] and preeclampsia [2.…”