The specific risks associated with renal colic during pregnancy are well characterized. Much of this literature, though, has been restricted to publications targeted primarily toward obstetricians, rather than urologists. Two small series were among the earliest descriptions of the effects of urolithiasis on pregnancy. Drago and associates reported on 9 pregnant women admitted for symptomatic kidney stones and 6 of them experienced preterm labor.[9] Hendricks and associates similarly reported on 15 pregnant women admitted for nephrolithiasis and 6 of them ultimately had preterm delivery.[10] Several analyses of large databases confirmed the findings reported in these small series. Specifically, Swartz and associates analyzed the state of Washington's hospital discharge data from 1987 through 2003.[11] They found that women admitted for nephrolithiasis had a significantly greater (adjusted odds ratio 1.8) risk of preterm delivery compared to women without stones. In 2003, Lewis and associates also reviewed over 21,000 deliveries in their database, and found that for the 86 patients diagnosed with a stone during pregnancy, there was an increased risk of preterm premature rupture of membranes (2.9% in non-stone patients vs. 7% in stone patients).[12] Preterm premature rupture of membranes is associated with an increased risk of morbidity and mortality to the newborn. In contradiction to the aforementioned reports, a group from Hungary studied a large population-based dataset from 1980 through 1996 and found no higher risk for adverse birth outcomes, specifically congenital anomalies, preterm birth, and low birth weight in newborns of pregnant women with nephrolithiasis.[13] Although this report is reassuring, it must be recognized that the source data for this study were obtained from patient questionnaires, and there were different compliance rates between the study and control groups. Taking these reports all together, though, nephrolithiasis during pregnancy remains a real concern. The subject of stone disease during pregnancy is particularly timely in the modern era, given the increasing incidence of kidney stone disease.
