Objective: To examine whether there were any differences in the endocrinological profiles during conception cycle and early pregnancy between a control group and women with a history of recurrent miscarriage that was caused by antiphospholipid syndrome and that was treated with aspirin and low molecular weight heparin. Design: Prospective observational study. Setting: Recurrent Miscarriage Clinic, Department of Obstetrics and Gynaecology in a tertiary care centre. Patient( s): Five women with recurrent pregnancy loss were recruited as cases, whereas another five women having natural cycle donor insemination were used as control. Intervention(s): Serial measurement of serum β-hCG, activin A, and inhibin A was performed from postovulatory day 12 until 11 weeks of gestation. Main OutcomeMeasure(s): Comparison of levels of β-hCG, activin A, and inhibin A at the time of conception onwards till 11 weeks in the two groups. Result(s): There were no significant differences between the two groups. Conclusion(s): There does not appear to be any obvious endocrinological alteration in the conception cycle of women with antiphospholipid syndrome compared with a control group. Furthermore, the initiation of heparin does not produce a significant change in activin A and inhibin A levels. Objective: To examine whether there were any differences in the endocrinological profiles during conception cycle and early pregnancy between a control group and women with a history of recurrent miscarriage that was caused by antiphospholipid syndrome and that was treated with aspirin and low molecular weight heparin. Design : Prospective observational study. Setting: Recurrent Miscarriage Clinic, Department of Obstetrics and Gynecology in a tertiary care center. Patient (s): Five women with recurrent pregnancy loss were recruited as cases, while another five women having natural cycle donor insemination were used as Control. Intervention (s): Serial measurement of serum β-hCG, activin A, and inhibin A was performed from postovulatory day 12 until 11 weeks of gestation. Main Outcome Measurement (s): Comparison of levels of β-hCG, activin A, and inhibin A at the time of conception onwards till 11 weeks in the two groups. Result (s): There were no significant differences between the two gro ups. Conclusion (s): There does not appear to be any obvious endocrinological alterations in the conception cycle of women with antiphospholipid syndrome compared with a control group. Furthermore, the initiation of heparin does not produce a significant change in activin A and inhibin A levels.