Pregnancy induces profound alterations in the maternal urinary system driven by hormonal shifts and increased volume requirements. Most notably, renal plasma flow and glomerular filtration rate increase significantly by the end of the first trimester, sometimes rising by up to fifty percent. This hyperfiltration state means the kidneys process waste products much faster than in the non-pregnant state. Consequently, normal serum levels of creatinine and urea drop noticeably; a creatinine value of 90 µmol/L that seems normal in a non-pregnant woman might actually indicate underlying renal impairment in an expectant mother.
Anatomically, progesterone causes relaxation of the smooth muscle in the ureters and renal pelvis, leading to hydronephrosis of pregnancy, which is more pronounced on the right side due to dextrorotation of the uterus and the cushioning effect of the sigmoid colon on the left. This urinary stasis, combined with the normal physiological glucosuria of pregnancy, creates an environment where bacteria can multiply easily, raising the risk of ascending infections.
Urinary tract infections represent one of the most frequent bacterial complications encountered in antenatal clinics across Nigeria. Midwives must distinguish between asymptomatic bacteriuria and symptomatic infections like acute cystitis or pyelonephritis. Asymptomatic bacteriuria occurs when significant bacteria colonies are present in the urine without the patient showing typical complaints of frequency or dysuria. If left untreated, a large percentage of these women will develop full-blown acute pyelonephritis, which carries serious risks such as preterm labour and maternal sepsis.
Screening via midstream urine culture should be performed at the first antenatal visit. When treatment is required, safe antibiotics such as nitrofurantoin or amoxicillin are prescribed based on local sensitivity patterns, avoiding agents like tetracyclines or quinolones that harm the developing fetus.
Acute pyelonephritis is a serious upper urinary tract infection that demands immediate admission and parenteral therapy.
Chronic kidney disease in pregnancy presents unique challenges depending on the baseline stage of renal impairment and the presence of associated hypertension. Women with mild chronic kidney disease often carry pregnancies to term successfully, though they face a much higher chance of developing superimposed pre-eclampsia and fetal growth restriction. As baseline renal impairment worsens, the risk of permanent loss of maternal kidney function accelerates, and the likelihood of successful fetal survival decreases correspondingly.
Multidisciplinary care involving obstetricians, nephrologists, and midwives is mandatory. Blood pressure control must be strict, using safe antihypertensive agents like methyldopa or labetalol, while avoiding ACE inhibitors and angiotensin receptor blockers due to their well-documented teratogenic effects on fetal renal development.
Acute kidney injury in obstetrics represents a sudden decline in renal function, historically referred to as acute renal failure. In resource-constrained settings, severe haemorrhage leading to hypovolaemic shock and severe sepsis from septic abortion or chorioamnionitis remain leading causes. Another major obstetric contributor is severe pre-eclampsia complicated by hemolysis, elevated liver enzymes, and low platelet count syndrome, which can precipitate acute tubular necrosis or cortical necrosis.
Early recognition relies on strict fluid balance charts and monitoring urine output—falling below 0.5 mL/kg/hour is an immediate red flag. Management focuses on treating the underlying trigger, restoring adequate circulating volume, correcting electrolyte disturbances, and preparing for emergency transfer to a facility with dialysis capabilities if conservative measures fail.