The question “will you be delivering my baby?” is one that pregnant women frequently ask their physicians. We sought to determine whether obstetric outcomes differed between women whose babies were delivered by their own obstetrician (regular-care obstetrician) and those attended by an on-call obstetrician who did not provide antenatal care.
We performed a cohort study of all live singleton term births between 1991 and 2001 at the Royal Victoria Hospital in Montréal. We excluded breech deliveries, elective cesarean sections and deliveries with placenta previa or prolapse of the umbilical cord. Logistic regression analysis was used to compare obstetric outcomes (e.g., cesarean delivery, instrumental vaginal delivery and episiotomy) between the regular-care and on-call obstetricians after adjustment for potential confounders.
A total of 28 332 eligible deliveries were attended by 26 obstetricians: 21 779 (76.9%) by the patient's own obstetrician and 6553 (23.1%) by the on-call obstetrician. Compared with women attended by their regular-care obstetrician, those attended by an on-call obstetrician had higher rates of cesarean delivery (11.9% v. 11.4%, adjusted odds ratio [OR] 1.13, 95% confidence interval [CI] 1.03–1.24, p < 0.01) and of third-or fourth-degree tears (7.9% v. 6.4%, adjusted OR 1.21, 95% CI 1.07–1.36, p < 0.01) but lower rates of episiotomy (38.5% v. 42.9%, OR 0.77, 95% CI 0.72–0.82, p < 0.001). No differences were observed between the groups in the rate of instrumental vaginal delivery. The increase in the overall rate of cesarean delivery among women attended by an on-call obstetrician was due mainly to an increase in cesarean deliveries during the first stage of labour because of nonreassuring fetal heart tracing (2.9% v. 1.7%, adjusted OR 1.79, 95% CI 1.49–2.15, p < 0.001). The time of day of delivery did not modify the observed effects.
The type of attending obstetrician (regular care v. on call) had a minor effect on obstetric outcomes.