The MFMU Cesarean Registry: uterine atony after primary cesarean delivery.
OBJECTIVE
The purpose of this study was to define independent risk factors for uterine atony after primary cesarean delivery, and to assess their overall association with atony in the study cohort.


METHODS
This was a 13-university center prospective observational study. All women who underwent primary cesarean from January 1, 1999 to December 31, 2000 were eligible. Trained and certified research nurses performed systematic data abstraction. The definition of atony required both the clinical diagnosis and the use of methergine or a prostaglandin preparation. Risk factors for uterine atony were assessed in univariable and multivariable logistic regression analyses, and these analyses then used to inform an assessment of the association of the various risk factors with the occurrence of uterine atony in the overall cohort.


RESULTS
Twenty-three thousand, three hundred and ninety pregnancies were analyzed. Uterine atony occurred in 1416 women (6%). Several variables were independently associated with atony in a multivariable model, including multiple gestation (odds ratio [OR] 2.40, 95% CI 1.95-2.93), maternal Hispanic race (2.21, 1.90-2.57), induced or augmented labor for >18 hours (2.23, 1.92-2.60), infant birth weight >4500 g (2.05, 1.53-2.69), and clinically diagnosed chorioamnionitis (1.80, 1.55-2.09). However, because the various risk factors were not very powerful, approximately half of the cases of atony were associated with the 2/3 of women lacking a given risk factor or combination of risk factors.


CONCLUSIONS
Although certain risk factors and uterine atony were clearly associated, the associations are of limited practical clinical use.
Rouse
Dwight J
DJ
Department of Obstetrics and Gynecology, Center for Research in Women's Health, University of Alabama at Birmingham, Birmingham, AL, USA.
Leindecker
Sharon
S
Landon
Mark
M
Bloom
Steven L
SL
Varner
Michael W
MW
Moawad
Atef H
AH
Spong
Catherine Y
CY
Caritis
Steve N
SN
Harper
Margaret
M
Wapner
Ronald J
RJ
Sorokin
Yoram
Y
Miodovnik
Menachem
M
O'Sullivan
Mary Jo
MJ
Sibai
Baha M
BM
Langer
Oded
O
D000328:Adult; D001724:Birth Weight; D002585:Cesarean Section; D005260:Female; D006801:Humans; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012042:Registries; D012044:Regression Analysis; D012307:Risk Factors; D014593:Uterine Inertia / Q000453:epidemiology*