Maternal chronic kidney disease (CKD) and chronic hypertension (CH) have been linked with adverse pregnancy outcomes. We aimed to examine the association between these conditions and adverse pregnancy outcomes over the last three decades, and to examine if the risk was modified by parity, maternal age, and body mass index (BMI). We also investigated whether different subtypes of CKD had differing effects.
We used data from the Swedish Medical Birth Register (MBR), including 2,788,490 singleton births between 1982 and 2012. Women with CKD and/or CH were identified from the MBR and National Patient Register. Logistic regression models were performed to assess the associations between maternal chronic disease (CH, CKD, or both conditions) on pregnancy outcomes, including pre-eclampsia (PE), in labor and pre-labor Caesarean sections (CS), preterm birth (PTB), small for gestational age (SGA) and stillbirth.
During the 30-year study period, 22,397 (0.8%) babies were born to women with CKD, 13,279 (0.48%) to women with CH and 1,079 (0.04%) to women with both conditions. Associations with CH were strongest for PE, (adjusted odd ratio (aOR)=4.57 [95% confidence interval, [4.33-4.84]), stillbirth (aOR=1.65 [1.35-2.03]), and weakest for spontaneous PTB (aOR=1.07 [0.96-1.20]). The effect of CKD varied from (aOR=2.05 [1.92-2.19]) for indicated PTB to no effect for stillbirth (aOR=1.16 [0.95-1.43]) . Women with both conditions had the strongest associations for in labor CS (aOR=1.86 [1.49-2.32]), pre-labor CS (aOR=2.68 [2.18-3.28]), indicated PTB (aOR=9.09 [7.61-10.7]), and SGA (aOR=4.52 [3.68-5.57]). The results remained constant over the last three decades. Stratified analyses of the associations by parity, maternal age and BMI showed that adverse outcomes remained independently higher in women with these conditions, with worse outcomes in multiparous women. All CKD subtypes were associated with higher odds of PE, in labor CS and medically indicated PTB. Different subtypes of CKD had differing risks, strongest associations of PE (aOR=3.98 [2.98-5.31]) and stillbirth (aOR=2.73 [1.13-6.59]) were observed in women with congenital kidney disease. Whereas women with diabetic nephropathy had the most pronounced increase odds of in labor CS (aOR=3.54 [2.06-6.09]), pre-labor CS (aOR=7.50 [4.74-11.9]), and SGA (aOR= 4.50 [2.92-6.94]). Additionally, Women with renovascular disease had the highest increased risk of preterm birth both spontaneous PTB (aOR= 3.01 [1.57-5.76]) and indicated PTB (aOR=8.09 [5.73-11.4]).
Women with CH, CKD or with both conditions are at increased risk of adverse pregnancy outcomes which were independent of maternal age, BMI, and parity. Multidisciplinary management should be provided with intensive clinical follow-up to support these women during pregnancy, particularly multiparous women. Further research is needed to evaluate the effect of disease severity on adverse pregnancy outcomes.

Copyright © 2021. Published by Elsevier Inc.