Plasminogen Activator Inhibitor-1 (PAI-1): Role in Adverse Pregnancy Outcome? - 6 - Treatment and Response Accompany Improved Outcomes

In the last several posts, we have presented support from the literature that links imbalances in the fibrinolytic system, as reflected in increased activity of PAI-1, or a genetic predisposition for the same, with adverse pregnancy outcome, both late and early in pregnancy. With regard to specific mechanisms contributing to recurrent pregnancy loss (RPL) in early pregnancy, we have reviewed evidence to support that aberrations of PAI-1 production could potentially have deleterious effects on ovulation, establishment and maintenance of the corpus luteum (which is essential for ‘progesterone support’ of early pregnancy), and early implantation/placentation of the embryo. In our final post (whew, finally!) on this subject, let’s look at data that would support the premise that down-regulation of PAI-1 production can be accomplished during pregnancy, or in anticipation of pregnancy, in ways that would be safe for both mother and baby, and might improve pregnancy success. At the outset, let me tell you that there is a plethora of information regarding ‘treatment’ of PAI-1 abnormalities under various clinical circumstances, but I would like to highlight only a few articles that pertain directly to pregnancy and RPL.

Bremer and colleagues in 1995 (Am J Obstet Gynecol 1995;172:986-91) performed a small study in which they “assessed the effects of a daily oral dose of 60 to 80 mg of aspirin from 12 weeks gestation until delivery on fibrinolytic variables before and after parturition…in 24 patients, eight receiving low-dose aspirin and 16 controls…The only maternal fibrinolytic variable affected…was plasminogen activator inhibitor activity, which showed a significant reduction before and after parturition of 40% and 70%, respectively, in low-dose aspirin users compared with controls.” None of these patients were reported to have significant pregnancy complications. Since aspirin is not known to have a direct effect on PAI-1 production or activity, it was concluded that the reduction in PAI activity is probably the result of inhibition of platelet reactivity.

In another study published the same year, Gris and colleagues (Thromb Haemost 1995;73:362-7) identified 30 women with a history of unexplained RPL and “an impaired fibrinolytic capacity.” Without identifying the specific reasons for their fibrinolytic imbalances, these women were randomized to begin prior to conception either low-molecular weight heparin (enoxaparin) 20 mg per day or a phenformin-like substance, moroxydine chloride, 1200 mg per day. After one month of treatment, if their fibrinolytic status normalized, therapy was continued for 6 months with the intention to continue treatment if they became pregnant; and, if their fibrinolytic status did not improve after one month, they were switched to the drug they did not receive the first time. The results were actually quite dramatic. With regard to normalization of fibrinolytic status, 20 out of 29 women responded to the first- or second-line enoxaparin treatment whereas did only 1 of 19 treated with moroxydine. Sixteen of 20 enoxaparin responders conceived compared to only 2 of 10 nonresponders (p = 0.002); and, 13 of 16 enoxaparin responder pregnancies resulted in live births compared to none of the 2 nonresponders (p = 0.02). This was compelling evidence that ‘anticoagulation therapy’ at subtherapeutic levels with a heparin compound might improve pregnancy outcome in women identified to have underlying hypofibrinolytic imbalances without even delving into the specific causes of these imbalances.

In 2000, Bick (Clin Appl Thromb Hemost 2000;6:115-25) reviewed the results of anticoagulation therapy in women with histories of RPL and no identifiable chromosomal, hormonal, or anatomical defects. Of the 160 women analyzed, 150 (94%) were found to have coagulation defects, and 38 were found to have more than one of the defects for which they were screened. Their mean age was 33 years and their mean number of miscarriages before referral was three. 149 women were treated preconceptionally with aspirin (81 mg/day) and, immediately following conception, were begun on unfractionated heparin 5000U every 12 hours, both of which were continued until delivery. The remarkable results of this study were that only 2 of the 149 women failed therapy and to have a live birth. This translates to a ‘success rate’ of 98%! In a subsequent report (Bick and Hoppensteadt, Clin Appl Thromb Hemost 2005;11:1-13), among 351 women with RPL who had no other identifiable cause, 322 (92%) were found to have coagulation abnormalities. Those with ‘thrombophilias’ were treated preconceptionally with aspirin (81 mg/day), to which was added following conception, unfractionated heparin (5000U/24 hr) in the first 120 patients, or the low molecular weight heparin, dalteparin (5000U/day), in the next 192 patients. (Patients with MTHFR polymorphisms were also treated with folic acid 5 mg /day and pyridoxine (vitamin B6) 50 mg/day). As the authors reported, “Only 2 of the thrombophilia patients suffered another miscarriage; all others had a normal term delivery” for an overall success rate of 94%.

Also in 2000, Glueck and colleagues (Fertil Steril 2000;74:396-7) presented a case report of a 32 year old woman with amenorrhea and infertility associated with polycystic ovary syndrome (PCOS) who had failure of 7 out of 10 IVF embryo transfers, 1 premature live birth, and two pregnancy losses at 8 and 17 weeks. She was obese, had high fasting serum insulin, androstenedione, and testosterone levels, and was also found to have a modest deficiency in protein S and the 4G4G polymorphism of PAI-1, accompanied by high PAI-1 activity. The combination of the protein S deficiency and the elevated PAI-1 characterized her as having “familial thrombophilia and hypofibrinolysis.” Although not overtly ‘diabetic’, she was begun on metformin (2.55 g/day) and a weight reduction program. Metformin is an oral drug used to treat type 2 diabetes. It improves blood sugar control by various mechanisms, decreasing glucose production by the liver, decreasing absorption of glucose in the gastrointestinal tract, and probably, most importantly, by increasing insulin sensitivity, accompanied by improved peripheral glucose uptake and utilization. Over the course of 4 months, her weight fell from 109 to 91.3 kg (16%), her insulin, androstenedione, and testosterone levels normalized, as did her PAI-1 activity levels.

As a follow-up to this case report, Glueck’s group (Fertil Steril 2001;75:46-52) reported preliminary results from an ongoing pilot study to determine whether metformin could reduce the rate of first trimester pregnancy loss in women with PCOS. They identified 19 women with PCOS who did not have overt diabetes and placed them on metformin (1.5-2.55 g/day) throughout pregnancy. Ten of the women had previously conceived but had miscarried 16 of their 22 pregnancies (73%). “While receiving metformin, these 10 women had 6 normal live births (60%), 1 spontaneous abortion (10%), and 3 normal ongoing pregnancies (30%)” all > 13 weeks. Up to the time of the report, among all 19 women receiving metformin, 9 (47%) had normal term live births, 2 (11%) had normal, but preterm births at 33 and 35 weeks, 6 (32%) had normal ongoing pregnancies beyond 1 weeks, 2 (10.5%) had first trimester miscarriages. No adverse maternal side-effects, nor birth defects were attributed to metformin in this small study. Most importantly, for purposes of our discussion here, “among women who received metformin before conception, reductions in insulin and plasminogen activator inhibitor activity were correlated (r = 0.65; P = .04).” Thus, metformin alone appeared to improve pregnancy outcome in a group of PCOS patients who had either had, or were at increased risk, for early pregnancy loss.

In a subsequent prospective study, Glueck and colleagues (Clin Appl Thromb Hemost 2004;10:323-34) evaluated the efficacy of combined therapy with metformin (1.5 to 2.55 g/day) and enoxaparin (60 mg/day) in women with PCOS and one or more previous early pregnancy losses, thrombophilia, and/or hypofibrinolysis. “Of the 24 women, 23 had 65 previous pregnancies…with 18 live births, 46 spontaneous abortions (71%), and one elective abortion.” Of these 23 women, seven had 3 or more consecutive losses, two had 2 consecutive losses, thirteen had 1 loss, and one woman had a live birth in a pregnancy complicated by HELLP syndrome. Compared to ‘controls’ with no history of adverse pregnancy outcome, the 24 women in this study had a higher frequency of the factor V Leiden mutation (17% vs.2%; P = 0.016), the PAI-1 4G4G polymorphism (46% vs 24%; P = 0.031), higher levels of the PAI-1 gene product and PAI-1 activity (33% vs 8%; P = 0.018), and a higher frequency of elevated factor VIII levels (22% vs 0%; P = 0.037). Of the 23 women who conceived on enoxaparin-metformin to date in the report, they had had 26 pregnancies (28 fetuses), with 20 live births, two ongoing pregnancies > 13 weeks, and 6 spontaneous early losses (21%), 3.4-fold lower than in their previous pregnancies. Again, no adverse maternal or fetal therapy effects were noted.

The articles cited above, have suggested that under various conditions associated with fibrinolytic imbalance and RPL, correction of the imbalance is at least a marker for, if not a direct contributor to, improved first trimester pregnancy success. None of these studies have really confirmed that improvement in pregnancy outcome could be directly correlated with reduction in PAI-1 activity. In the early 1980’s it became recognized that women with PCOS, who ovulated poorly or not at all, would sometimes benefit from partial removal (wedge resection) of their ovaries, or even complete removal of an ovary. This was frequently accompanied by spontaneous ovulation and a decrease in the male hormones (androgens) that can be produced in excess by the ovaries of women with PCOS. Various techniques were employed over the years to reduce the ovarian tissue mass that resulted in the hormonal imbalances accompanying PCOS, but in 1989, Daniell and Miller (Fertil Steril 1989;51:232) described a laparoscopic technique termed ‘ovarian drilling’ in which 4-20 hormone-producing follicles (cysts) on one or both ovaries were pierced and cauterized using laser or electrocautery techniques. This procedure resulted in a dramatic decrease in male hormone levels within days, spontaneous ovulation in 70-90% of women, and a 40-60% probability of pregnancy within a year. Palomba and colleagues (Fertil Steril 2005;84:761-5) performed a comparative study of women with PCOS and elevated PAI-1 levels who underwent ovarian drilling with or without treatment with metformin. Ovarian drilling alone did not reduce PAI-1 activity, whereas metformin administration did. Furthermore they found that a lack of decrease in PAI-1 activity was related to a high risk of miscarriage in those women who conceived following ovarian drilling. These findings suggest that fibrinolytic imbalance, characterized by elevated levels of PAI-1, is an independent risk factor for RPL.

In closing, let me return to one more study by Glueck and colleagues (Metabolism 2006:55:345-52) that we cited in an earlier post. We mentioned previously that results in this study of women with PCOS demonstrated that PAI-1 activity was independently and positively associated with risk for first trimester miscarriage and that “for each 5 IU/mL increment in PAI-1 activity, the risk of being in an adverse first-trimester miscarriage category increased.” What we did not mention before is that prospectively, women in this study were placed on metformin prior to conception and their subsequent pregnancy outcome was assessed and correlated with changes in PAI-1 activity. “From pretreatment to the last preconception visit on glucophage (metformin), in 30 women who subsequently had live births, PAI-1 activity fell 44%, but rose 19% in 23 (also metformin treated) women with first-trimester miscarriage (P = 0.03).” Furthermore, “in the 30 women with live birth pregnancies, median PAI-1 activity fell continuously through the first trimester…, whereas PAI-1 activity was either unchanged or rose in women with first-trimester miscarriage.” Therefore, not only is increased PAI-1 activity an independent risk factor for RPL, but failure of response to therapy, as reflected in lack of normalization of PAI-1 levels also appears to be as well.

At the outset of this series, I dedicated the work to one of our readers (IR) who has had recurrent miscarriages and asked me many months ago about my thoughts on the relationship of PAI-1 activity and RPL. During the course of reviewing the literature I have come to the conclusion that there certainly is a correlation between the two. Perhaps the most compelling evidence resides in the observations that ‘appropriate’ PAI-1 activity appears to be a part of normal ovulation and implantation/placentation in early pregnancy. It is easy to speculate how imbalances at these critical times could interfere with early pregnancy success, regardless of the underlying causes that led to these imbalances. It would appear that efforts to improve a ‘hypofibrinolytic’ state, reflected in women with RPL and increased PAI-1 activity, should be considered as part of any therapeutic regimen. Preconceptional weight reduction, if indicated, treatment with metformin, low-dose aspirin, supplemental folic acid and B-vitamins, ovulation induction with progesterone support, and prophylactic use of heparin or low-molecular weight heparin under these conditions are all options that can be employed and have a wide margin of safety for both mother and baby.

So, IR, I hope this helps. And, I really hope that sometime soon you conceive the baby you are destined to carry. I know you will be a great Mom!
Dr T

Labels: fibrinolysis, PAI-1, recurrent pregnancy loss

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