NDT Advance Access originally published online on July 3, 2009
Nephrology Dialysis Transplantation 2009 24(12):3744-3750; doi:10.1093/ndt/gfp320
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Kidney function and future risk for adverse pregnancy outcomes: a population-based study from HUNT II, Norway
1 Faculty of Medicine, Institute of Cancer Research and Molecular Medicine 2 Faculty of Medicine, Department of Public Health, Norwegian University of Science and Technology 3 Department of Nephrology, St Olav University Hospital, Trondheim 4 Renal Research Group, Institute of Medicine, University of Bergen 5 Department of Medicine, Haukeland University Hospital, Bergen, Norway
Correspondence and offprint requests to: John Munkhaugen; E-mail: john{at}munkhaugen.org
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Abstract |
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Background. Current knowledge on prepregnancy reduced kidney function and the risk of adverse pregnancy outcomes mainly relies on small studies in selected populations. We aim to investigate whether reduced kidney function is associated with the risk of adverse pregnancy-related outcomes in the general population.
Methods. A population-based study linking all women attending the Second Health Study in Nord-Trøndelag, Norway (1995–97) and subsequent pregnancies registered in the Medical Birth Registry. Multivariable random-effect logistic regression analysis was used to explore the association between renal function and study outcome.
Results. The mean eGFR among 3405 women was 107.6 ± 19.4 ml/min/1.73 m2 at baseline; 18.8% and 0.1% had eGFR of 60–89 and <60, respectively. Over the next 11 years, they gave birth to 5655 singletons of whom 885 (17.7%) were complicated with preeclampsia, small for gestational age (SGA) or preterm birth. Women with eGFR 60–89 were not at increased risk for this combined outcome compared to women with eGFR 
90, although women with eGFR 60–74 tended to have an increased risk. Neither was reduced kidney function a risk factor among women with microalbuminuria, but those with an eGFR of 60–89 plus hypertension had a significantly increased risk: odds ratios for preeclampsia, SGA or preterm birth were 2.58 (95% CI 1.40–4.75, P < 0.001) and 10.09 (95% CI 2.38–42.87, P < 0.001) in hypertensive women with eGFR 75–89 and 60–74, respectively. Relative excess risk due to interaction between reduced kidney function and hypertension was 2.23 (95% CI 1.35–3.10, P < 0.001). Women with a reduced kidney function were not at increased risk for other pregnancy complications like caesarean section, maternal bleeding, dystocia, pre-labour rupture of membranes, Apgar score 
7, stillbirth or congenital malformations.
Conclusions. Women with eGFR 60–89 ml/min/1.73 m2 were not at increased risk for preeclampsia, SGA or preterm birth unless they were also hypertensive.
Keywords: glomerular filtration rate; mild reduced kidney function; population-based cohort study; pregnancy outcome
Received for publication: 28. 1.09
Accepted in revised form: 8. 6.09