Common determinants of breech presentation at birth in singletons: a population-based study Hendrik Cammu a, b, *, Noëlie Dony b , Guy Martens a , Roos Colman c a Study Centre of Perinatal Epidemiology, Brussels, Belgium b Department Obstetrics & Gynaecology, University Hospital, VU Brussels, Belgium c Biostatistics Unit, University Ghent, Belgium A R T I C L E I N F O Article history: Received 17 December 2013 Received in revised form 10 March 2014 Accepted 8 April 2014 Keywords: Determinants breech presentation Parturition A B S T R A C T Objective: To estimate common determinants of breech presentation at parturition. Study design: A population-based cohort study (between 1/1/2001 and 31/12/2010) was conducted among all women who delivered a singleton baby in breech presentation from 22 completed weeks of gestation. A binary logistic regression was used to determine independent feto–maternal characteristics of breech presentation at birth, adjusted odds ratios and 95% confidence intervals. Variables were: gestational age, birth weight, maternal age, parity and gender of the baby, presence or absence of a history of cesarean section, gestational diabetes, gestational hypertension, pregnancy after assisted reproduction technology and congenital malformations. Results: From a population of 611,021 women; 28,059 were delivered in breech presentation (4.59%). Independent determinants of breech presentation at delivery were: gestational age and birth weight (the lower, the higher the incidence of breech at birth), parity (the frequency of breech decreased with increasing parity) and maternal age (the older the mother, the higher the odds for breech presentation). Women who had a scarred uterus, due to a previous cesarean section, women who gave birth to a female offspring and women whose baby showed a congenital malformation, were more prone to be delivered in breech presentation. Conclusion: Low gestational age and birth weight, advanced maternal age, a scarred uterus, a female baby and a baby with a congenital malformation increased the odds for singleton breech presentation at parturition. The latter gradually decreased with increasing parity. ã 2014 Elsevier Ireland Ltd. All rights reserved. Introduction The overall incidence of breech presentation at birth is between 4 and 5%. The lower the gestational age, the more frequent the baby lies in the breech position. At 28 weeks, for instance, 22% present by breech, at term it is less than 4% [1]. The most common cause of breech presentation is therefore preterm delivery. Nearer term, a breech presentation must be the result of something preventing a spontaneous version to the vertex position. This may be due to mechanical factors such as uterine abnormalities or a contracted pelvis. Fetal growth retardation, oligo- or polyhydramnios and fetal malformations such as hydrocephalus are also recognized causes of breech presentation. However, all these factors are found in only a small amount of breech presentations and usually no single cause of the breech presentation can be identified [2]. This study aimed at making an inventory of common obstetrical characteristics that are inde- pendently associated with breech presentation at parturition. To that end we conducted a population-based cohort study. Materials and methods Flanders, the Dutch speaking northern part of the constitution- ally federal state of Belgium, has 6.2 million inhabitants and on average 62,000 births per year of which 99% take place in the hospital maternity units. All of the following data were derived from the computer files of the Study Centre for Perinatal Epidemiology (SPE). The SPE is an independent, regionally funded, centre that registers all births of >500 g and/or 22 weeks gestation. For each newborn, a standard perinatal form is completed (mostly by the midwife) and sent to the SPE where all data are checked by an error detection program and feedback is given. During the study period 1/1/2001–31/12/2010, 613,356 singleton births were registered of which 4.6% were born in breech presentation. We * Corresponding author at: Academic Hospital VU Brussels, Laarbeeklaan 101, 1090 Brussels, Belgium. Tel.:+ +32 479 38 21 92. E-mail address: hendrik.cammu@uzbrussel.be (H. Cammu). http://dx.doi.org/10.1016/j.ejogrb.2014.04.008 0301-2115/ ã 2014 Elsevier Ireland Ltd. All rights reserved. European Journal of Obstetrics & Gynecology and Reproductive Biology 177 (2014) 106–109 Contents lists available at ScienceDirect European Journal of Obstetrics & Gynecology and Reproductive Biology journal homepage: www.else vie r.com/locat e/e jogrb