We would like to bring to your readers’ attention an issue with pregnancy management with history of shoulder dystocia (SD), as recommended by Overland et al in the Journal’s May issue. In a large sample of vaginal deliveries during a 38-year period in Norway, the absolute risk of SD recurrence was 7.3%. They find that the most important risk factor for SD recurrence is very high birthweight (BW) and recommend planned cesarean for women with previous SD and estimated fetal weight (EFW) >4500g. This is based on recurrence rates of 19.9% (BW, 4500–5000 g) and 29.2% (BW, >5000 g).

It should be noted, though, that per American College of Obstetricians and Gynecologists recommendations, cesarean should already be under consideration at these EFWs—4500 g for diabetics and 5000 g for nondiabetics, regardless of pregnancy history—therefore not accounting for additional risk associated with prior SD. In fact, in the Norwegian series, recalculated from the Table, risk with previous SD is increased 3× from 3000–3500 g, >5× from 3500–4500 g, 3× from 4500–5000 g, and <2× for >5000 g. Overall, starting at a pound less than the mean, risk of recurrent SD was increased approximately 3-fold.

We suggest that our published recommendation —cesarean should be considered for those with higher EFW than the previous SD BW—may be more clinically useful than recommendations based only on current pregnancy EFW. Our study was smaller (205 previous SDs) and from a single institution, but it assessed all other published series; overall SD recurrence risk was 10%, about 10× higher than risk without previous SD. Our suggestion was based on a discriminant analysis, linear model, which suggested that risk goes up linearly with increased BW in second pregnancies. Just what the decision cut point should be is likely a function of ethnicity of the population served, local cesarean rate, base rate of SD, and medicolegal climate. “Doctor, with fetal size being the most important determinant of shoulder dystocia, for this woman who’d already had shoulder dystocia, you decided to have her deliver this bigger baby vaginally? … Guilty!!”

Given a >30% background cesarean rate in the United States, judicious use of cesarean to avoid recurrence is reasonable. Our suggestion to compare current offspring EFW with previous BW, even given estimation difficulties, may well be a safer strategy for the patient, her offspring, and her obstetrician, failing the availability of clinical trial results.