Vaginal birth after cesarean for cephalopelvic disproportion: effect of birth weight difference on success.
OBJECTIVE
To estimate the effect of birth weight difference between the current and index pregnancy on vaginal birth after cesarean (VBAC) failure in patients whose prior cesarean was for cephalopelvic disproportion (CPD).


METHODS
This was a retrospective cohort study of women with one cesarean for CPD, comparing the rate of VBAC failure in women whose infant was smaller, the same, or larger in the VBAC attempt compared with cesarean. The primary outcome was VBAC attempt failure, defined as a patient who attempted VBAC but subsequently required a cesarean delivery for any indication. Univariable, stratified, and multivariable analyses were used.


RESULTS
Of 13,706 patients attempting VBAC, 1,511 had one prior cesarean delivery for CPD. Compared with patients with the same birth weight, a lower birth weight was associated with fewer failed VBAC attempts (29.6% compared with 37.8%, adjusted odds ratio [OR] 0.7, 95% confidence interval [CI] 0.5-1.0) and a higher birth weight was associated with more failed VBAC attempts (54.5% compared with 37.8%, adjusted OR 2.0, 95% CI 1.5-2.8).


CONCLUSIONS
Birth weight difference has a moderate effect on the rate of VBAC success in patients whose prior cesarean delivery was for CPD.


METHODS
II.
From the Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
Lorie M
LM
Harper
David M
DM
Stamilio
Anthony O
AO
Odibo
Jeffrey F
JF
Peipert
George A
GA
Macones
D000328:Adult; D001724:Birth Weight; D052178:Cephalopelvic Disproportion / Q000601:surgery; D005260:Female; D006801:Humans; D011247:Pregnancy; D012189:Retrospective Studies; D016064:Vaginal Birth after Cesarean / Q000706:statistics & numerical data*; D055815:Young Adult
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