Antiphospholipid syndrome (APS) represents a serious risk factor in pregnancy resulting in several complications, leading to fetal loss and hemostatic complications. In this dedicated report, we describe our experiences in the treatment of pregnancies in patients with APS. The retrospective data from 140 pregnant women were investigated, and the treatment results of 121 patients were recorded. We studied two groups of patients receiving different treatment. The first group (N = 78) received the standard therapy with low-weight-molecular heparin (dalteparin 5000 U or certoparin 3000 U daily) and aspirin (100 mg daily) and in the second group (N = 43) an additional 0.2 g/kg intravenous immunoglobulin (IVIG). Outcomes were 74.3% and 83.7% live births in the first group and in the second group, respectively. The abortion rate was similar in both groups (11.5% vs. 11.6%). The late complication rate was lower in the second group (5.8% vs. 14.1%, P < 0.05) than in the group with standard therapy. Interestingly, we found a trend to higher percentage (> 12%) of natural killer (NK) cells in patients with pregnancy complications (60% vs. 12%, P < 0.05). Our retrospective data shows an improvement of late pregnancy complications by additional use of IVIG. It is possible that IVIG influences higher NK cell activity in patients with previous pregnancy complications.