title: 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.
authors.affiliation: Fondazione Ca' Granda,Ospedale Maggiore Policlinico,Infertility Unit,Milan,Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Sarais
authors.affiliation: Fondazione Ca' Granda,Ospedale Maggiore Policlinico,Infertility Unit,Milan,Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Paffoni
authors.affiliation: Fondazione Ca' Granda,Ospedale Maggiore Policlinico,Infertility Unit,Milan,Italy.
authors.forename: Giulia Maria
authors.initials: GM
authors.lastname: Baffero
authors.affiliation: Department of Obstetrics and Gynecology,University of Milan,Milan,Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Parazzini
authors.affiliation: Fondazione Ca' Granda,Ospedale Maggiore Policlinico,Infertility Unit,Milan,Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Persico
authors.affiliation: Fondazione Ca' Granda,Ospedale Maggiore Policlinico,Infertility Unit,Milan,Italy.
authors.forename: Edgardo
authors.initials: E
authors.lastname: Somigliana
mesh_terms: D000328:Adult; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005006:Ethnicity; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D059285:Pregnancy, Twin; D011296:Prenatal Diagnosis / Q000379:methods*; D012189:Retrospective Studies; D012307:Risk Factors; D018401:Sample Size; D014427:Twins
keywords: IVF; in vitro fertilization; monochorionic; monozygotic; twin