Subclinical pregnancy loss in clomiphene citrate-treated women

To ascertain the subclinical pregnancy loss rate in clomiphene citrate (CC)-treated infertile women compared with women of normal fertility.

Following a prospective format, serum samples were taken during the luteal phase of 92 menstrual cycles associated with CC treatment and 47 cycles in normal women. Human chorionic gonadotropin (hCG) assay sensitivity was 0.25 IU/L. Human chorionic gonadotropin assay was validated against 95 nonpregnant cycles. Criterion for pregnancy was a single serum sample greater than or equal to 0.5 IU/L.

All subjects were under clinical management at the University of Virginia Health Sciences Center.

Patients undergoing CC induction of ovulation with satisfactory ovulatory response were candidates for the study group (n = 34). Control subjects of proven normal fertility were recruited (n = 22). Nonpregnant control subjects were sexually abstinent or had been surgically sterilized (n = 89).

A serum sample was taken during the late luteal phase of all subjects.

Thirteen percent of CC-treated cycles and 4.3% of normal control cycles were subclinical losses (P = 0.09). Fifty percent of CC-induced pregnancies were subclinical losses compared with 16.6% of normal control pregnancies (P = 0.05). Of CC patients who had at least one subclinical loss 47.6% later conceived a term pregnancy compared with 15.3% who did not have a subclinical loss (P = 0.06).

Subclinical pregnancy loss is more common in CC-treated women than normal women and may be a predictor of subsequent normal conception.