Pregnancy outcomes in women with chronic kidney disease and chronic hypertension: a National cohort study

BACKGROUND: Maternal chronic kidney disease and chronic hypertension have been linked with adverse pregnancy outcomes. We aimed to examine the association between these conditions and adverse pregnancy outcomes over the last 3 decades. OBJECTIVE: We conducted this national cohort study to assess the association between maternal chronic disease (CH, CKD or both conditions) and adverse pregnancy outcomes with an emphasis on the effect of parity, maternal age, and BMI on these associations over the last three decades. We further investigated whether different subtypes of CKD had differing effects. STUDY DESIGN: We used data from the Swedish Medical Birth Register, including 2,788,490 singleton births between 1982 and 2012. Women with chronic kidney disease and chronic hypertension were identified from the Medical Birth Register and National Patient Register. Logistic regression models were performed to assess the associations between maternal chronic disease (chronic hypertension, chronic kidney disease, or both conditions) and pregnancy outcomes, including pre-eclampsia, in-labor and prelabor cesarean delivery, preterm birth, small for gestational age, and stillbirth. RESULTS: During the 30-year study period, 22,397 babies (0.8%) were born to women with chronic kidney disease, 13,279 (0.48%) to women with chronic hypertension and 1079 (0.04%) to women with both conditions. Associations with chronic hypertension were strongest for pre-eclampsia (adjusted odds ratio, 4.57; 95% confidence interval, 4.33-4.84) and stillbirth (adjusted odds ratio, 1.65; 95% confidence interval, 1.35-2.03) and weakest for spontaneous preterm birth (adjusted odds ratio, 1.07; 95% confidence interval, 0.96-1.20). The effect of chronic kidney disease varied from (adjusted odds ratio, 2.05; 95% confidence interval, 1.92-2.19) for indicated preterm birth to no effect for stillbirth (adjusted odds ratio, 1.16; 95% confidence interval, 0.95-1.43). Women with both conditions had the strongest associations for in-labor cesarean delivery (adjusted odds ratio, 1.86; 95% confidence interval, 1.49-2.32), prelabor cesarean delivery (adjusted odds ratio, 2.68; 95% confidence interval, 2.18-3.28), indicated preterm birth (adjusted odds ratio, 9.09; 95% confidence interval, 7.61-10.7), and small for gestational age (adjusted odds ratio, 4.52; 95% confidence interval, 3.68-5.57). The results remained constant over the last 3 decades. Stratified analyses of the associations by parity, maternal age, and body mass index showed that adverse outcomes remained independently higher in women with these conditions, with worse outcomes in multiparous women. All chronic kidney disease subtypes were associated with higher odds of preeclampsia, in-labor cesarean delivery, and medically indicated preterm birth. Different subtypes of chronic kidney disease had differing risks; strongest associations of preeclampsia (adjusted odds ratio, 3.98; 95% confidence interval, 2.98-5.31) and stillbirth (adjusted odds ratio, 2.73; 95% confidence interval, 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 cesarean delivery (adjusted odds ratio, 3.54; 95% confidence interval, 2.06-6.09), prelabor cesarean delivery (adjusted odds ratio, 7.50; 95% confidence interval, 4.74-11.9), and small for gestational age (adjusted odds ratio, 4.50; 95% confidence interval, 2.92-6.94). In addition, women with renovascular disease had the highest increased risk of preterm birth in both spontaneous preterm birth (adjusted odds ratio, 3.01; 95% confidence interval, 1.57-5.76) and indicated preterm birth (adjusted odds ratio, 8.09; 95% confidence interval, 5.73-11.4). CONCLUSION: Women with chronic hypertension, chronic kidney disease, or both conditions are at an increased risk of adverse pregnancy outcomes which were independent of maternal age, body mass index, 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.