For the purpose of this study gestational age was added to the confounders in the analyses of CS, preeclampsia and birth selleck inhibitor weight based on their clinically well-known associations.25 28 29 The OR for instrumental vaginal delivery was calculated

among women with vaginal births only in order to exclude women with an instrumental attempt to deliver followed by an emergency CS. The ORs of perineal lacerations were also estimated among women with vaginal births only. The information concerning use of epidural analgesia was also restricted to vaginal births only. Epidural is an analgesic method that has been widely used in the delivery wards for vaginal births during the entire time period. In contrast the use of epidural analgesia in CS has varied substantially over the time period and has almost exclusively been used in elective CS. Our purpose was to evaluate the OR for epidural use over the maternal age strata and consequently we selected the mode of delivery that exhibited the least variation in the use of the analgesic method over the time period, that is, vaginal births. Table 1 Descriptive data of primiparous women with singleton births in the period 1992–2010 The software STATISTICA 64 V.10 (StatSoft Inc 2300

East 14th St. Tulsa, Oklahoma 74104, USA) was used to carry out the statistical analyses. Results In the period 1992–2010, 798 732 women were registered in the MBR as giving birth to their first child. The annual number of primiparous

women giving birth varied between 34 060 and 49 417. Information on maternal age was missing in 58 cases leaving 798 674 women for the analyses. The average age of primiparous women increased substantially from 26.2 years in 1992 to 28.5 in 2004; thereafter it has stayed almost constant at that level. The demographic, obstetric and neonatal data subdivided into maternal age groups are presented in tables 1 and ​and22. Table 2 Obstetric and neonatal outcome characteristics of primiparous women with singleton births in the period 1992–2010 The crude odds rates and the results of the multivariate analyses models of obstetric and neonatal outcomes are shown in tables 3 and ​and4,4, respectively. Table 3 Obstetric outcome Entinostat data in singleton primiparous women in the period 1992–2010 in relation to maternal age group Table 4 Neonatal outcome data in singleton primiparous women in the period 1992–2010 in relation to maternal age group Mode of delivery, obstetric and neonatal outcome of adolescents Compared with the reference group the teenagers had a significantly higher likelihood of having spontaneous onset of labour and of having a normal vaginal delivery. Teenagers also demonstrated a significantly higher risk of giving birth prematurely.