Study objective: To investigate the relative contributions of the corpus luteum (CL) and the placenta to the circulating levels of relaxin during pregnancy.
Patients: Forty-one patients in whom pregnancy had been achieved by ovum donation.
Results: Relaxin was not detected in the serum of 36 patients; in the remaining 5, although it was detectable, the levels were markedly reduced when compared with those in normal pregnancies.
Conclusion: These results demonstrate that the CL is essential for the maintenance of normal circulating levels of relaxin during pregnancy.