Author(s): Rosalie M Grivell 1 , Jodie M Dodd 2
cesarean section; gestational age; induction of labor; maternal complications; neonatal complications
How common is induction of labor for term pregnancy?
Induction of labor (IOL) is common, with approximately 25% of births in Australia each year occur following IOL  . Across Europe, rates of induced labor range from less than 9% in the Baltic countries and the Czech Republic to 30.7% in Northern Ireland and 37.9% in Malta  . Rates of IOL in Australia have increased over time, from 19.5% in 1991 to 24.8% in 2008, although over recent years the proportion has remained static  .
While IOL may be performed for a range of accepted or recognized maternal or fetal indications, a significant proportion occur in the absence of pregnancy complications. Across Australia, there is variability in data collection methods and reporting by individual jurisdictions, which, combined with indications for IOL not being included in the national perinatal dataset, makes comparisons of indications for IOL between states difficult  . In jurisdictions where indications for IOL are recorded, recognized indications include diabetes, prelabor rupture of the membranes, hypertensive disorders, intrauterine growth restriction, isoimmunization, fetal distress, fetal death, chorioamnionitis and prolonged pregnancy  .
Data from two jurisdictions in Australia indicates that approximately 50% of inductions beyond 37 weeks' gestation were performed in the absence of recognized maternal or fetal indications  . There is a little published information from the perspective of either obstetricians or pregnant women evaluating possible reasons for the increase in IOL and decision-making in this clinical situation.
The factors contributing to the observed increase in IOL for nonrecognized indications remain unclear, as does the impact of such a practice on maternal and infant health outcomes.
IOL & maternal risks
The practice of 'elective' IOL or IOL at term in the absence of medical or obstetric indications is controversial. While some authors have suggested that adopting a 'preventive IOL' policy at term is associated with improved maternal and infant birth outcomes [3,4] , others have raised concern regarding a 'cascade of intervention', increasing in particular the risk of cesarean section and maternal morbidity  . Establishing an accurate estimate of the possible risks associated with elective IOL is further hampered by the lack of available data specifically comparing maternal and infant health outcomes by onset of labor.
Evidence of an increased risk of adverse maternal outcomes is supported by a number of large retrospective studies that have attempted to examine maternal health outcomes comparing spontaneous onset with labor following induction.
Women who experience elective IOL are more likely to require a cesarean birth. This finding is consistent across a number of datasets reported from the USA, Canada and Australia [6-8] .
In a large retrospective review of 115,828 births in the USA, elective IOL was associated with an increased risk of caesarean section  when compared with spontaneous labor. Similar results were reported by Boulvain et al. , who evaluated almost 7500 women with an uncomplicated term pregnancy, again comparing outcomes with the onset of labor ...