Serum levels of CA 125 during the first trimester of normal outcome, ectopic and anembryonic pregnancies

Single serum samples were obtained during the first trimester of pregnancies with a retrospectively normal outcome ( n = 150), ectopic pregnancies ( n = 38) and anembryonic pregnancies ( n = 78). Serial samples during the first trimester were also obtained from 43 women achieving pregnancy following successful treatment for infertility and with a retrospectively defined normal outcome. Significant variation in serum CA 125 levels in relation to gestational age was observed in pregnancies with a normal outcome ( P > 0.0001). Peak serum CA 125 levels were observed at 6−7 weeks, the mean level at this gestation being 40.1 U/ml (range 31.7-50.7 U/ml) in the normal conception/normal outcome group and 36.5 U/ml (range 25.6-52.0 U/ml) in the assisted conception/normal outcome group. A rise and fall in serum CA 125 levels during the first trimester was observed in 42 of 43 assisted conceptions monitored serially, with peak levels ranging from 7 to 1398 U/ml (median 48.8 U/ml) occurring at 28−61 days (median 45 days) gestation. Mean serum CA 125 levels were higher in the anembryonic pregnancy group at 4−5 and 6−7 weeks gestation than in both normal pregnancy outcome groups ( P > 0.01).