Fetal Complications In Women Research Articles

Anticoagulation of Pregnant Women With Mechanical Heart Valves

The management of women with prosthetic heart valves during pregnancy poses a particular challenge as there are no available controlled clinical trials to provide guidelines for effective antithrombotic therapy. Oral anticoagulants such as warfarin sodium cause fetal embryopathy; subcutaneous administration of heparin sodium has been reported to be ineffective in preventing thromboembolic complications. To identify the risks of maternal and fetal complications in women with mechanical heart valves treated with different anticoagulation regimens during pregnancy. We performed a systematic review of the literature to determine pooled estimates of maternal and fetal risks associated with the 3 commonly used approaches: (1) oral anticoagulants (OA) throughout pregnancy, (2) replacing OA with heparin in the first trimester (from 6-12 weeks' gestation), and (3) heparin use throughout pregnancy. Fetal outcomes included spontaneous abortions and fetopathic effects, and maternal outcomes were major bleeding, thromboembolic complications, and death. The use of OA throughout pregnancy is associated with warfarin embryopathy in 6.4% (95% confidence interval [CI], 4.6%-8.9%) of livebirths. The substitution of heparin at or prior to 6 weeks, and continued until 12 weeks, eliminated this risk. Overall risks for fetal wastage (spontaneous abortion, stillbirths, and neonatal deaths) were similar in women treated with OA throughout, compared with women treated with heparin in the first trimester. Maternal mortality was 2.9% (95% CI, 1.9%-4.2%). Maj or bleeding events occurred in 2.5% (95% CI, 1.7%-3.5%) of all pregnancies, most at the time of delivery. The regimen associated with the lowest risk of valve thrombosis (3.9%; 95% CI, 2.9-5.9%) was the use of OA throughout; using heparin only between 6 and 12 weeks' gestation was associated with an increased risk of valve thrombosis (9.2%; 95% CI, 5.9%-13.9%). Thromboembolic prophylaxis of women with mechanical heart valves during pregnancy is best achieved with OA; however, this increases the risk of fetal embryopathy. Substituting OA with heparin between 6 and 12 weeks reduces the risk of fetopathic effects, but with an increased risk of thromboembolic complications. The use of low-dose heparin is definitely inadequate; the use of adjusted-dose heparin warrants aggressive monitoring and appropriate dose adjustment. Large prospective trials to determine the best regimen for these women are needed.

Plasma active and inactive renin and fetal complications in women with high risk pregnancies

To examine whether the activation of the renin system, which occurs during pregnancy, may be relevant for the development and the outcome of the fetus, we measured active and inactive renin throughout gestation in 29 women having a pregnancy defined as "high risk" because of a clinical history of hypertension, nephropathy, and unexplained abortions. In 23 of these women who delivered full-term infants with normal weight and status, we found that active renin increased progressively from early pregnancy until the end of the second trimester and then declined slightly thereafter. In contrast, in the remaining six women who had fetal complications consisting of either signs of distress requiring cesarean section or growth retardation, the increase in active renin failed to occur. In all women the levels of inactive renin were more elevated throughout gestation than those observed in nonpregnant women, and were higher, although not significantly, in women without fetal complications than in those with fetal complications. Thus, a blunted activation of the renin system during pregnancy is associated with alteration in fetal development and may possibly contribute to it.