Estimating the Risk of Monochorionic Twins in IVF Pregnancies From the Perspective of a Prenatal Diagnosis Unit

Abstract

The aim of the present work was to estimate the risk of monochorionic twin (MCT) pregnancies in in vitro fertilization (IVF) cycles using data from a prenatal diagnosis unit. This was a retrospective cross-sectional study reporting on the frequency of IVF pregnancies among women attending a prenatal diagnosis service specifically dedicated to the management of monochorionic pregnancies. The observed rate was compared with the local regional rate of IVF births (2.2%). A binomial distribution model was used to calculate the 95% CI of proportions. One hundred and forty-five monochorionic pregnancies were selected. Ten of these were achieved with IVF, corresponding to a rate of 6.9% (95% CI: 3.5-11.8), significantly higher than the background rate in the local population of 2.2%. When considering exclusively monochorionic pregnancies achieving delivery of two viable newborns (n = 132), the number of IVF pregnancies was nine (6.8%, 95% CI: 3.7-12.5). We did not detect major differences in pregnancy outcome between IVF and natural monochorionic pregnancies, with the exception of the proportion of newborns with a neonatal birth < 2,500 g (100% vs. 80%, p = .03). In conclusion, data obtained from the perspective of a prenatal diagnosis unit suggest that women undergoing IVF face a 3-to 4-fold increased risk of monochorionic pregnancies.

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

“…TTTS is the most common cause of excess mortality in monochorionic twin gestations 36 , however we did not observe a higher incidence of TTTS in the IVF/ICSI group. This in agreement with the results of earlier studies 13,14,16,28 . One study even reported a lower incidence of TTTS in MCDA pregnancies conceived after IVF 37 , but the authors excluded pregnancies that resulted in the loss of one or both twins, which is often the result of TTTS.…”

“…The rate of IVF/ICSI in our cohort was 12%, which may seem high compared with some series 14,16 , but it is comparable with, or even lower than, the rate in other studies 13,28 . This high proportion of IVF/ICSI pregnancies may be related to the reimbursement policy for IVF treatment in Belgium.…”

“…Pregnancies were classified according to the mode of conception as spontaneous vs IVF or ICSI (IVF/ICSI). Pregnancies resulting from ovulation induction were not included in the analysis in order to create a more homogeneous study group and facilitate comparison with earlier published series 13,14,16,28 . Women who conceived after insemination in a natural cycle, without ovulation induction, were included in the spontaneous-conception group, and women who conceived after egg donation were included in the IVF/ICSI group.…”

“…It is uncertain how IVF affects the outcome of monochorionic twin pregnancies, which are already at higher risk of adverse pregnancy outcome than dichorionic pregnancies because of the presence of vascular anastomoses and potential transfusion imbalances 12 . Given its increased use, it is essential to understand better whether IVF further affects the outcome of these twins; however, the findings of studies on this topic are inconsistent [13][14][15] . Some authors have suggested lower survival rates in monochorionic diamniotic (MCDA) twins after IVF, but their results failed to show statistical significance, most probably owing to small sample size 14,16,17 .…”

“…Given its increased use, it is essential to understand better whether IVF further affects the outcome of these twins; however, the findings of studies on this topic are inconsistent [13][14][15] . Some authors have suggested lower survival rates in monochorionic diamniotic (MCDA) twins after IVF, but their results failed to show statistical significance, most probably owing to small sample size 14,16,17 . Moreover, significant methodological differences between the studies makes their comparison difficult.…”