The unpredictability and variations in obstetric patient load make staffing anesthesiologists on the labor floor very difficult. If we were more aware of the actual workload patterns, then we could improve obstetric anesthetic service. Some studies1–3suggest that patients’ circadian rhythms influence delivery times; others4–7suggest that institutional factors exert a greater influence.

To help us determine delivery patterns, we recently reviewed data we collected during a 3-month period from our labor and delivery unit at Lucile Packard Children’s Hospital, Stanford, California. Our institution, a tertiary referral center with dedicated day and night obstetric anesthesia coverage, performs more than 5,000 deliveries per year. Of these deliveries, 25–30% are cesarean, and the labor epidural rate is > 80%. Up to four cesarean deliveries are scheduled daily (Monday to Friday), but only one is scheduled per day on the weekends. We admit patients to the labor and delivery suite at 7 am for induction of labor.

Figure 1compares the scheduled number of cesarean deliveries with the actual number of cesarean deliveries (scheduled plus nonscheduled) that occur during a week. Although the majority of scheduled cesarean deliveries were performed on Tuesday, Wednesday, and Thursday, the actual cesarean deliveries peaked on Thursday and Friday. Figure 2shows a similar peak (Thursday and Friday) in the weekly pattern of total (vaginal and cesarean) number of deliveries. The mean ± SD number of total deliveries per day during the week was 14.2 ± 4.5 compared with the 12.7 ± 4.2 during the weekend (P = 0.13). The mean ± SD of actual cesarean deliveries per day during the week was 3.6 ± 1.9 compared with 3.0 ± 1.6 during the weekend (P = 0.15).

A number of studies have found that institutional factors are more influential than natural factors on the delivery workload.4–7Despite the fact that scheduled cesarean deliveries at our institution account for 53% of our total cesarean deliveries, the scheduled ones did not appear to impact the overall cesarean workload pattern. Our results show that despite a bias toward more scheduled cesarean deliveries earlier in the week, the peak workload occurs in the latter part of the week. We are not sure why this workload bias exists. Clinicians may increase cesarean deliveries on Thursday and Friday in anticipation of the weekend. Induction policies may influence overall cesarean delivery times more than do scheduled deliveries. We did not find that cesarean and total deliveries were significantly reduced over the weekend. Reduced weekend and night coverage may give clinicians the impression of an increased workload.

We recommend that institutions review their obstetric workload to help plan their anesthetic coverage and staffing requirements. Obstetricians’ practices and organizations vary greatly among institutions. Our findings suggest that increasing the number of scheduled cesarean deliveries earlier in the week may compensate for the increased deliveries in the latter part of the work week, evening out the workload throughout the week. Our obstetricians and nursing management are aware of these workload biases and plan to use this data to organize future staffing and scheduling changes. However, constraints related to physicians, nurses, patients, and families may make altering weekly patterns in cesarean delivery workload very difficult. In addition, the benefits derived from institutional and/or patient factors that have cause these observed biases may outweigh the increased costs related to this nonuniform, less-efficient workload pattern.

Lucile Packard Children’s Hospital, Stanford University School of Medicine, Stanford, California.

Anderka M, Declercq ER, Smith W: A time to be born. Am J Public Health 2000; 90:124–6
Moore TR, Iams JD, Creasy RK, Burau KD, Davidson AL: Diurnal and gestational patterns of uterine activity in normal human pregnancy. The Uterine Activity in Pregnancy Working Group. Obstet Gynecol 1994; 83:517–23
Germain AM, Valenzuela GJ, Ivankovic M, Ducsay CA, Gabella C, Seron-Ferre M: Relationship of circadian rhythms of uterine contraction with term and preterm delivery. Am J Obstet Gynecol 1993; 168:1271–7
Carvalho B, Coghill J: Obstetric anaesthesia workload and time of day. Int J Obstet Anesth 2004; 13:126–8
Matijevic R, Johnston TA, Maxwell R: Timing of initiation of induction of labour can affect out of hours work. BMJ 1998; 316:393–4
Jarvelin MR, Hartikainen-Sorri AL, Rantakallio P: Labour induction policy in hospitals of different levels of specialisation. Br J Obstet Gynaecol 1993; 100:310–5
Spetz J, Smith MW, Ennis SF: Physician incentives and the timing of cesarean sections: Evidence from California. Med Care 2001; 39:536–50