Contribution of changing risk factors to the trend in breech presentation at term

Abstract

Background: Recent population-wide changes in perinatal risk factors may affect rates of breech presentation at birth, and have implications for the provision of breech services and clinical training in breech management. Aims:To determine the trend in breech presentation at term and investigate whether changes in maternal and pregnancy characteristics explain the observed trend. Annual rates of breech presentation were determined. Logistic regression modelling was used to predict expected rates of breech presentation over time and these were compared with observed rates. A priori predictors included maternal age, country of birth, parity, smoking during pregnancy, diabetes, pregnancy hypertension, placenta praevia, previous singleton term breech, previous caesarean section, infant sex, gestational age, birthweight, and congenital anomalies. Hospital and Medicare data were used to assess trends in external cephalic version.Results: Among 914,147 singleton term births, 3.1% were breech at delivery. Rates declined from 3.6% in 2002 to 2.7% in 2012 (test for trend p<0.001). Breech presentation was predicted to increase from 3.6% in 2002 to 4.3% in 2012 because of increased maternal age, nulliparity, maternal diabetes, history of breech presentation and previous caesarean section. Use of external cephalic version appears to have increased over time.Conclusions: Breech presentation at delivery has decreased in New South Wales.Increased use of external cephalic version likely accounts for this decline, as changes in risk factors do not.

Preterm Birth, Low Gestational Age, Low Birth Weight, Parity, and Other Determinants of Breech Presentation: Results from a Large Retrospective Population-Based Study

“…Differently from our data and from the analysis by Cammu et al [1], no specific association between previous cesarean section and breech presentation was observed in the study by Frucalzo et al [3]. Moreover, additional risk factors for breech delivery, not included in our analysis, emerged in the above-mentioned studies, such as the presence of congenital malformations [1], decreased intra-amniotic fluid [9], or maternal smoking during pregnancy [2, 9].…”

“…In particular, low birth weight, low gestational age, advanced maternal age, primiparity and a female baby emerged as independent risk factors for breech delivery in several previous papers [1–3, 9, 10]; on the contrary, for some other conditions, inconsistent results were described. Differently from our data and from the analysis by Cammu et al [1], no specific association between previous cesarean section and breech presentation was observed in the study by Frucalzo et al [3].…”

A comparison of risk factors for breech presentation in preterm and term labor: a nationwide, population-based case–control study

“…We found that in term pregnancies, breech presentation was associated with advanced maternal age, nulliparity, maternal hypothyroidism, pre-gestational diabetes, placenta praevia, PROM, oligohydramnios, fetal congenital anomaly, female sex of the fetus, and birth weight below the tenth percentile. A previous cesarean section is known to be positively related to the odds of having a fetus in breech presentation at term [5,14], and in our study, this risk factor started to show already in moderate to late preterm pregnancies. Instead of the scar being the cause of breech presentation, it is more likely that the women with a history of breech cesarean section have, during subsequent pregnancies, a fetus in breech presentation again or have a cesarean section for another reason [3,5,37].…”

“…In the earlier gestation and excluding PPROM, breech deliveries did not differ in obstetric risk factors compared to cephalic. The risk factors in 32 weeks of gestational age are comparable to those in term pregnancy, and several of these factors, such as low birth weight, congenital anomalies and history of cesarean section, are associated with adverse fetal outcomes [1,4,5,8,14,17] and must be taken into account when treating breech pregnancies. Risk factors should be evaluated prior to offering a patient an external cephalic version, as the presence of some of these risks may increase the change of failed version or fetal intolerance of the procedure.…”

Singleton breech presentation at term: Review of the evidence and international guidelines for application to the New Zealand context

“…It is estimated that breech presentation occurs in 3-4% of all births, with the proportion of breech presentations decreasing as gestational age increases, so that 1-3% of all pregnancies will be breech at term (Thorogood & Donaldson, 2015). A recent review of term breech presentation in New South Wales, Australia, identified an overall rate of 3.1% in a population of 914,147 singleton term births over the period from 2002 to 2012 (Bin, Roberts, Nicholl, Nassar, & Ford, 2016). Over these years the annual rate decreased from 3.6% in 2002 to 2.7% in 2012 due to the increasing use of external cephalic version (ECV).…”