Hemodialysis Prescription in Pregnant Women

Pregnancy in women receiving dialysis is an uncommon occurrence but a growing reality in recent years (1). With improved therapeutic advancements, the literature suggests a 3- to 6-fold increase in dialysis pregnancy rates from 1996–2000 to 2001–2013 (1–3). Despite significant improvements in live birth rates, these pregnancies remain high risk with significant adverse maternal fetal complications, including preeclampsia and preterm birth (3). Preterm babies of mothers receiving dialysis have twice the odds of serious adverse events, including higher resuscitation needs and neonatal intensive care admissions (3).

The management of hemodialysis in pregnancy is subject to variability internationally. Hemodialysis prescriptions often reflect influencing factors, including patient health status, lifestyle, and geography. Hemodialysis accessibility is also dependent on jurisdictional availability of infrastructure and resources. There are numerous challenges to consider when prescribing hemodialysis in pregnancy, including dialysis regimens, ultrafiltration (UF), and nutritional requirements. To date, there are no randomized controlled studies evaluating regimens in pregnancy, with optimal management left to consensus opinion supported by limited case series and cohort studies. Our recommendations for dialysis prescriptions are outlined in Table 1.

Table 1.

Dialysis prescription recommendations during pregnancy

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PlGF, placental growth factor; sFlt-1, soluble fms-like tyrosine kinase 1. Table created based on Hladunewich et al. (4), Cabiddu et al. (5), and Wiles et al. (6).

Both fertility and pregnancy outcomes are improved with intensive hemodialysis (>36 hours) compared with conventional hemodialysis (<20 hours), with a demonstrated dose response relationship (4). It is hypothesized that the increase of uremic clearance is the underlying driver of improved pregnancy outcomes, including live birth rates, advanced gestational age, and a trend toward larger newborns (4). Amplified dialysis from the first trimester works to maintain maternal circulating volume, blood pressure, and interdialytic weight gain and in turn, reduces use of antihypertensive agents (4). Given the burden of intensive regimens, it is important to adjust the regimen based on residual kidney function with a goal to maintain urea <35 mg/dL(5, 6).

The UF prescription in pregnancy is challenging and needs to be individualized (5). Maternal weight gain and blood volume expansion throughout pregnancy should be balanced against the severe hemodynamic changes and rapid volume depletion that can occur with hemodialysis and, in turn, cause detrimental placental flow disruptions affecting the fetus. For this reason, cautious UF is recommended with the goal of minimizing hemodynamic instability and hypotension (5).

Adequate nutrition is critical to maternal and fetal well-being. It is estimated that pregnant women receiving dialysis require increased caloric support (approximately 35 kcal/kg) in addition to standard pregnancy caloric increments for each trimester (6). Protein intake of 1.2–1.8 g/kg/day of pregestational weight is also required to support fetal development (6). Additionally, folic acid, zinc, and water-soluble vitamins are recommended from the first trimester. Electrolyte imbalances are common, and supplementation of potassium, calcium, and even phosphate may be required with intensive dialysis. Typically, a 3K potassium bath is prescribed.

Anemia is more common in pregnant women receiving hemodialysis, and iron deficiency is linked to worse perinatal outcomes. All women should receive oral or parenteral iron supplementation. Pregnancy is postulated to be a state of relative erythropoietin (Epo) resistance, requiring an average 50% increase in supplemental Epo to achieve the target hemoglobin 10–11 g/dL with no documented teratogenic or hypertensive risks (5).

Hemodialysis during pregnancy is complex. Preconception counseling and multidisciplinary team management are paramount. The trifactor of dialysis intensification, judicious UF, and maternal nutritional support remains the cornerstone of supporting these high-risk pregnancies.