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Keywords:

  • Postpartum haemorrhage;
  • pre-eclampsia;
  • preterm birth;
  • retained placenta;
  • small for gestational age;
  • stillbirth

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.

Design

Population-based cohort study.

Setting

Sweden.

Population

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.

Main outcome measure

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.