Indicators for Cervical Length in Twin Pregnancies.
OBJECTIVE
Cervical length (CL) is associated with the risk of preterm birth (PTB) in multiple pregnancies. However, the position of CL within the pathophysiological pathway of PTB is unclear, and it is unknown which factors are predictive for CL. This study aims to investigate whether in twin pregnancies baseline maternal and obstetrical characteristics are potential indicators for CL, to improve insight in the pathophysiological pathway of PTB.


METHODS
Secondary analysis of data on twin pregnancies and CL measurement between 16 and 22 weeks. A set of 10 potential indicators, known to be associated with an increased risk of PTB and/or which have a plausible mechanism resulting in a change of CL were selected. We used multivariable linear regression with backward selection to identify independent indicators for CL.


RESULTS
A total of 1,447 women with twin pregnancies were included. Mean CL was 43.7 (±8.9) mm. In multivariable analysis, age (0.27 mm/y; 95% confidence interval [CI] 0.16 to 0.39), use of assisted reproductive technologies (ART) (-1.42 mm, 95% CI -2.6 to -0.25), and having delivered at term in a previous pregnancy (1.32 mm, 95% CI 0.25 to 2.39) were significantly associated with CL.


CONCLUSIONS
This study shows that in twin pregnancies, age, use of ART and having delivered term in a previous pregnancy has an association with CL.
Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands.
Frederik J R
FJ
Hermans
Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands.
Ewoud
E
Schuit
Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands.
Sophie M S
SM
Liem
Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands.
Arianne C
AC
Lim
Department of Obstetrics and Gynaecology, Erasmus Medical Centre, Rotterdam, The Netherlands.
Johannes
J
Duvekot
Department of Obstetrics and Gynaecology, Academic Hospital Maastricht, Maastricht, The Netherlands.
Liesbeth C J
LC
Scheepers
Department of Obstetrics and Gynaecology, Radboud University Medical Centre, Nijmegen, The Netherlands.
Mallory M
MM
Woiski
Department of Obstetrics and Gynaecology, University Medical Center Groningen, Groningen, The Netherlands.
Maureen M
MM
Franssen
Department of Obstetrics and Gynaecology, University Medical Centre Utrecht, Utrecht, The Netherlands.
Martijn A
MA
Oudijk
Department of Obstetrics and Gynaecology, Leiden University Medical Centre, Leiden, The Netherlands.
Kitty W M
KW
Bloemenkamp
Department of Obstetrics and Gynaecology, Isala Clinics, Zwolle, The Netherlands.
Bas Nij
BN
Bijvanck
Department of Obstetrics and Gynaecology, Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands.
Dick J
DJ
Bekedam
Clinical Research Unit, Academic Medical Center, Amsterdam, The Netherlands.
Brent C
BC
Opmeer
The Robinson Research Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Australia.
Ben Willem J
BW
Mol
D000328:Adult; D054791:Cervical Length Measurement; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D008403:Mass Screening; D015999:Multivariate Analysis; D009426:Netherlands; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D059285:Pregnancy, Twin / Q000706:statistics & numerical data*; D047928:Premature Birth / Q000453:epidemiology*; D027724:Reproductive Techniques, Assisted