Genetic variant of luteinizing hormone in women with a history of recurrent miscarriage.

Because the biological and clinical significance of a genetic variant of luteinizing hormone (LH) is unclear, we therefore evaluated the occurrence of variant LH in women with a history of recurrent spontaneous abortion (RSA) and related it to specific LH concentrations, luteal function and pregnancy outcome. Of the 85 RSA women, 30 (35.3%) had variant LH (28 heterozygous and two homozygous), and 55 women (64.7%) a normal wild-type LH ratio. These frequencies are similar to those reported from the general Finnish population. No significant differences were observed in specific LH concentrations based on LH status (7.2+/-1.4 IU/l, mean +/- SEM, variant LH, versus 8.5+/-1.6 IU/l, wild-type LH). Variant LH was twice as common in women with body mass index (BMI) > 25 kg/m2 (9/15, 60.0%) than in those with BMI < or =25 kg/m2 (21/70, 30.0%, P < 0.05). The presence of variant LH was not associated with any clear effect on endocrine variables such as endometrial maturation or mid-luteal phase oestradiol and progesterone concentrations. During follow-up, 23 women with variant LH (76.7 %) and 41 with wild-type LH (74.5%) became pregnant: 14 miscarried (21.9%, six with variant LH and eight with wild-type LH) and two had ectopic pregnancies, whereas 48 (75.0%) succeeded (17 with variant LH and 31 with wild-type LH). LH concentrations before pregnancy were similar in women with a successful outcome (8.0+/-1.3 IU/l) or with a miscarriage also in that pregnancy (7.4+/-1.4 IU/l). In conclusion, variant LH is common in RSA women who are relatively overweight (BMI > 25 kg/m2) but its presence is not reflected in endometrial maturation and miscarriage rates.