Can obstetric complications explain the high levels of obstetric interventions and maternity service use among older women? A retrospective analysis of routinely collected data

Objective To determine whether the higher levels of obstetric intervention and maternity service use among older women can be explained by obstetric c omplications. Design A retrospective analysis of routinely collected data from the Aberde en Maternity and Neonatal Databank. Participants All residents of Aberdeen city district delivering singleton i nfants at the Maternity Hospital 1988-1997 (28,484 deliveries). Main outcome measures Odds ratios for each intervention in older maternal a ge groups compared with women aged 20-29. Interventions considered include obstetric interventions (induction of tabour, augmentation, epidural use, a ssisted delivery, caesarean section) and raised maternity service use (more than two prenatal scans, amniocentesis, antenatal admission to hospital, a dmission at delivery of more than five days, infant resuscitation, and admi ssion to the neonatal unit). Methods Logistic regression was used to investigate the association between maternal age and the incidence of interventions. The odds ratios for each intervention were then adjusted for relevant obstetric complications and ma ternal socio-demographic characteristics. Results Levels of amniocentesis, caesarean section, assisted delivery, indu ction, and augmentation (in primiparae) are all higher among older women. M aternity service use also increases significantly with age: older women are more likely to have an antenatal admission, more than two scans, a hospita l stay at delivery of more than five days, and have their baby admitted to a neonatal unit. Controlling for relevant obstetric complications reveals s everal examples of effect modification, but does not eliminate the age effe ct for most interventions in most groups of women. Conclusions Higher levels of intervention among older women are not explain ed by the obstetric complications we considered.