Premature Birth Ups Risk of Kidney Disease Into Adulthood

Pam Harrison

May 08, 2019

Being born prematurely is associated with a significantly greater risk of developing chronic kidney disease (CKD) from childhood into mid-adulthood, a national cohort study in Sweden indicates.

Even infants born between 37 and 38 weeks' gestation ("early" rather than premature) have a higher risk of developing CKD into mid-adulthood, although the risk is somewhat attenuated as gestational age increases, the study shows.

"The third trimester of pregnancy is the most active period of fetal nephrogenesis, during which more than 60% of nephrons are formed," write Casey Crump, MD, PhD, Icahn School of Medicine at Mount Sinai, New York City, and colleagues, in their article published online May 1 in BMJ.

"Our findings underscore the importance of public health strategies to prevent preterm birth, including better access to preconception and prenatal care for high risk women, and reduction of nonmedically indicated deliveries before full term," they indicate.

They also give advice for physicians on how to monitor patients born prematurely to try to reduce/limit their risk of developing kidney disease.

Association Strongest in Childhood

The Swedish birth registry was used to identify 4,195,249 singleton live births that took place in Sweden between 1973 and 2014.

"Overall, 4305 (0.1%) participants had a diagnosis of CKD," the researchers observe.

"Preterm birth and extremely preterm birth (< 28 weeks) were associated with a nearly twofold and threefold risk of CKD, respectively, from birth into mid-adulthood [compared with full-term birth (P < .001)]," they add.

Infants born between 37 and 38 weeks' gestational age were also 30% more likely to develop CKD into mid-adulthood compared with full-term birth infants (hazard ratio [HR], 1.30; P < .001).

Indeed, across the entire age range from 0 to 43 years, gestational age at birth was inversely associated with risk of CDK at an adjusted HR of 0.92 for each additional week of gestation (P < .001), Crump and colleagues point out. 

"These associations were strongest in childhood," Crump notes. For example, the risk of developing CKD was highest for participants between the ages of 0 to 9 years, when it was over five times higher for preterm infants relative to their full-term counterparts.

This association weakened as people got older but it was still significant for those between the ages of 10 and 19, when CKD risk was almost twice as high for those born preterm compared with those born at full term (HR, 1.97; P < .001).

And for those between the ages of 20 and 43, risk of CKD was still about one third higher for those born preterm, compared with at-term, at an HR of 1.34, the investigators add.

And among the 4305 participants who developed CKD over the study interval, over one third (34.2%) progressed to end-stage renal disease (ESRD).

Again, across all age categories, the adjusted HR for ESRD was still twice as high for preterm infants compared with full-term infants (HR, 2.09; P < .001).

For infants born early, the risk was still high (adjusted HR, 1.44; P < .001).

The increased risk of CKD associated with preterm birth was evident in both males and females (P < .001 for both genders).

Effects Likely Because of In Utero Kidney Development

As the authors note, outcomes did not appear to be influenced by any shared genetic or environmental factors in families but rather were likely because of the direct effect prematurity has on in utero kidney development.

To preserve renal function in patients born extremely prematurely, prematurely, or early, Crump and colleagues recommend clinicians do the following:

  • Include birth history to trigger preventive actions in those identified as having been born prematurely.

  • Counsel patients on potential sources of nephrotoxicity including nonsteroidal anti-inflammatory drugs and recurrent urinary tract infections.

  • Maintain well-controlled blood pressure.

  • Reduce risk factors for CKD including obesity, diabetes, dyslipidemia, anemia, and smoking.

  • Monitor renal function periodically.

  • Because low nephron count might result in accelerated loss of kidney function, caution patients born prematurely not to donate a kidney.

The prevalence of preterm birth is approximately 10% in the United States and slightly less, at between 5% and 8%, in Europe.

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