• Anthropometric indices of progeny;
  • progression of pregnancy

PROBLEM: Phase II clinical trials with the heterospecies dimer of βhCG and α-subunit of ovine luteinizing hormone (HSD)-human chorionic gonadotropin (hCG) vaccine showed that pregnancy was prevented at and above 50 ng/ml titers, whereas conceptions occurred below 35 ng/ml of hCG bioneutralization capacity. The effect of below-protective threshold anti-hCG antibodies on the progression of pregnancy and the normality of progeny was studied.

METHOD OF STUDY: Four women enrolled by informed consent in the Phase II trials. The women studied were immunized with the HCG vaccine and did not receive booster injections in consideration of their desire to have another child. They were examined clinically at least once every month until delivery. The babies were followed up from 2 to 3.5 years, and their anthropometric indices were compared with elder siblings.

RESULTS: The pregnancies progressed to 35 to 38 weeks with the usual obstetric problems, and the children developed normally.

CONCLUSIONS: The anti-fertility effect of the HSD-hCG vaccine is reversible and low titers of antibodies below the protective threshold have no apparent side effects on the progression of pregnancy and on the early development of the progeny.