Retained placenta is associated with pre-eclampsia, stillbirth, giving birth to a small-for-gestational-age infant, and spontaneous preterm birth: a national register-based study.
OBJECTIVE
To evaluate whether defective placentation disorders, i.e. pre-eclampsia, stillbirth, small for gestational age (SGA), and spontaneous preterm birth, are associated with risk of retained placenta.


METHODS
Population-based cohort study.


METHODS
Sweden.


METHODS
Primiparous women in Sweden with singleton vaginal deliveries between 1997 and 2009 at 32-41 weeks of gestation (n = 386,607), without placental abruption or infants with congenital malformations.


METHODS
Risks were calculated as odds ratios (ORs) by unconditional logistic regression with 95% confidence intervals (95% CIs) after adjustments for maternal, delivery, and infant characteristics.


METHODS
Retained placenta, defined by the presence of both a diagnostic code (of retained placenta) and a procedure code (for the manual removal of the placenta).


RESULTS
The overall rate of retained placenta was 2.17%. The risk of retained placenta was increased for women with pre-eclampsia (adjusted OR, aOR, 1.37, 95% CI 1.21-1.54), stillbirth (aOR 1.71, 95% CI 1.28-2.29), SGA birth (aOR 1.47, 95% CI 1.28-1.70), and spontaneous preterm birth (32-34 weeks of gestation, aOR 2.35, 95% CI 1.97-2.81; 35-36 weeks of gestation, aOR 1.55, 95% CI 1.37-1.75). The risk was further increased for women with preterm pre-eclampsia (aOR 1.69, 95% CI 1.25-2.28) and preterm SGA birth (aOR 2.19, 95% CI 1.42-3.38). There was no association between preterm stillbirth (aOR 1.10, 95% CI 0.63-1.92) and retained placenta, but the exposed group comprised only 15 cases.


CONCLUSIONS
Defective placentation disorders are associated with an increased risk of retained placenta. Whether these relationships indicate a common pathophysiology remains to be investigated.
Department of Clincal Science and Education, Division of Obstetrics and Gynaecology, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden.
M
M
Endler
S
S
Saltvedt
S
S
Cnattingius
O
O
Stephansson
A-K
AK
Wikström
D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D016015:Logistic Models; D016017:Odds Ratio; D018457:Placenta, Retained / Q000453:epidemiology / Q000209:etiology*; D011225:Pre-Eclampsia; D011247:Pregnancy; D047928:Premature Birth; D012042:Registries; D012307:Risk Factors; D050497:Stillbirth; D013548:Sweden
Postpartum haemorrhage; pre-eclampsia; preterm birth; retained placenta; small for gestational age; stillbirth