Relaxin has a role in establishing a renal response in pregnancy.

Women with normal ovarian function (n = 9) and women who conceived with ovum donation (no circulating relaxin; n = 9) had serial measurements of renal function made during the first trimester of pregnancy by using 24-hour creatinine clearance (CrCl) and plasma osmolality (P(osm)). All pregnancies were associated with increasing CrCl and reduced P(osm), but the change from baseline was significantly greater in the women with normal ovarian function, indicating that in contrast to the rodent model, other factors in addition to circulating relaxin contribute to gestational renal adaptation to human pregnancy.