UKOSS Update


Incidence and risk factors for placenta accreta/increta/percreta[1]

  • The presence of placenta accreta/increta/percreta is associated with major pregnancy complications, and is thought to be becoming more common, due to a number of factors including rising maternal age at delivery and an increasing proportion of deliveries by caesarean.
  • The aims of this study were to estimate the incidence of placenta accreta/increta/percreta in the UK and to investigate and quantify the associated risk factors.
  • 134 women were diagnosed with placenta accreta/increta/percreta between May 2010 and April 2011 and 256 control women; an estimated incidence of 1.7 per 10 000 maternities.
  • Women who had a previous caesarean delivery (adjusted odds ratio [aOR], 14.41; 95% confidence interval [CI], 5.63–36.85), other previous uterine surgery (aOR, 3.40; 95% CI, 1.30–8.91), an IVF pregnancy (aOR, 32.13; 95%CI, 2.03–509.23) and placenta praevia diagnosed antepartum (aOR, 65.02; 95% CI, 16.58–254.96) had raised odds of having placenta accreta/increta/percreta.
  • There were also raised odds of placenta accreta/increta/percreta associated with older maternal age in women without a previous caesarean delivery (aOR, 1.30; 95% CI, 1.13–1.50 for every one year increase in age).
  • The estimated incidence is 577 per 10 000 in women with both a previous caesarean delivery and placenta praevia; there is a need to maintain a high index of suspicion of abnormal placental invasion in such women and preparations for delivery should be made accordingly.

Pregnancy in renal transplant recipients[2]

  • Most studies reporting pregnancy outcomes in women with kidney transplants are either single-centre studies, small, or report historical cohorts identified over long periods.
  • The aim of this study was to collect information about pregnancy outcomes among a current cohort of all kidney transplant recipients in the UK.
  • There were 105 pregnancies identified in 101 recipients between January 1, 2007 and December 31, 2009.
  • Pre-eclampsia developed in 24% compared with 4% of a comparison cohort.
  • 52% of women with kidney transplants delivered preterm, significantly higher than the national rate of 8%.
  • Twenty-four infants (24%) were small for gestational age (<10th centile).
  • Potential predictive factors for poor pregnancy outcome included >1 previous kidney transplant (= 0.03), first trimester serum creatinine >125 mmol/L (= 0.001), and diastolic BP >90 mmHg in the second (= 0.002) and third trimesters (= 0.05).
  • This study shows that most pregnancies in the UK in women with kidney transplants are successful but rates of maternal and neonatal complications remain high.


Thank you to all members who contributed information to these studies.

Further information

Details of these and other UKOSS study results can be obtained from the UKOSS website If you would like a reprint of any UKOSS publications please contact