Serum inhibin A levels in pregnant women with systemic lupus erythematosus or antiphospholipid syndrome

Abstract

Maternal serum inhibin A levels are increased on average in pregnancies affected by Down syndrome (DS). However, some reports have found increased serum levels in women with pre-eclamptic toxaemia as well. In the current study, maternal serum inhibin A was retrospectively measured in a series of 32 serum samples from pregnant women previously diagnosed as having either systemic lupus erythematosus (SLE) or primary antiphospholipid syndrome (APS). For comparison, normal medians were calculated from 57 unaffected control pregnancies together with a total of 854 samples tested at 13-19 weeks of gestation as part of the routine antenatal DS screening. All results were expressed in multiples of the gestation specific normal medians (MoM). A cubic regression formula was fitted, weighting for the number of women tested at each gestation. The median MoM value in the 16 cases of SLE and the 16 cases of primary APS is 0.60 (95% confidence interval 0.40-0.91) and 0.88 (95% confidence interval 0.66-1.17), respectively. For primary APS this was not statistically significant, whereas the SLE patients had a highly statistically significant reduction of serum inhibin A (p<0.002, Wilcoxon Rank sum Test, 2 tailed). Six pregnancies in the SLE group had a complicated obstetric outcome, i.e. missed abortion, placental abruption, exacerbation of the underlying disease which necessitated delivery, and severe postpartum haemorrhage. In 85% of this subgroup, serum inhibin A levels were below the normal 10th centile. The current data suggest that serum inhibin A is decreased on average in SLE patients. Those preliminary results might have various obstetric implications such as antenatal DS screening of SLE patients, identification of pregnant women at risk of developing SLE, who have presented for routine DS screening and for monitoring SLE patients throughout their pregnancy.