Previous cesarean birth. A risk factor for placenta previa?
OBJECTIVE
To study the risk of placenta previa following a previous cesarean birth.


METHODS
We conducted a population-based, case-control study using 1990 North Carolina state birth certificate data. The study population included 342 women with a pregnancy complicated by placenta previa and 1,082 randomly selected controls. Analysis was restricted to women who reported one or more previous live births and delivered a singleton, live neonate. Adjusted odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated using logistic regression, controlling for maternal age, race, prior spontaneous or induced abortions and cigarette use.


RESULTS
When the data were adjusted for maternal age, race, prior spontaneous or induced abortions, and cigarette use, women who had a previous cesarean birth and had a parity of 3 were 1.7 times more likely (OR 1.7, 95% CI 0.7, 4.2) and women of parity > or = 4 were 5.5 times more likely (OR 5.5, 95% CI 1.0, 30.1) to have placenta previa than women of parity 1 who had a previous cesarean birth.


CONCLUSIONS
Women with a history of a previous cesarean birth and parity > or = 3 were at increased risk of having a pregnancy complicated by placenta previa.
McMahon
M J
MJ
Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill 27599-7570, USA.
Li
R
R
Schenck
A P
AP
Olshan
A F
AF
Royce
R A
RA
D000028:Abortion, Induced; D000022:Abortion, Spontaneous; D000328:Adult; D016022:Case-Control Studies; D002585:Cesarean Section / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008423:Maternal Age; D016017:Odds Ratio; D010298:Parity; D010923:Placenta Previa / Q000209:etiology*; D011247:Pregnancy; D044469:Racial Groups; D012307:Risk Factors; D012907:Smoking