Oral contraceptives in the immediate postpartum period

Journal of Family Practice, April, 1991 by Anne L. Hume, Juman C. Hijab

The immediate puerperium, the time between delivery and hospital discharge, represents an important opportunity for the physician to review contraceptive options with the patient. The need for effective contraception in the postpartum period is well recognized, since women who choose not to breast-feed could resume having ovulatory cycles before the traditional 6 or 8 weeks postpartum visit. [1] Women who are given bromocriptine for the suppression of physiologic lactation could ovulate as soon as 2 to 3 weeks after deliver. [2]

Even though there is the potential for the postpartum woman to become pregnant again, the inherent risks of contraceptive methods must be evaluated critically during this period. Specifically, oral contraceptives can present an increased risk of thromboembolism in the immediate postpartum period. The following is a case presentation and review of the issues concerning thromboembolism associated with the use of oral contraceptives in the early postpartum period.

Case Report

The patient was a 21-year-old woman (gravida 2, para 2) who was 4 weeks postpartum when she first noted the onset of pain and swelling in her right lower calf and a mottled discoloration from the proximal thigh to her toes. The pain worsened with walking and radiated to her upper thigh. She denied any trauma to the area and did not have a history of phlebitis or pulmonary embolism. Her only medication was a triphasic oral contraceptive (Triphasil), which had been started 1 week after delivery. The patient reported that she had just finished her first pack of pills. Her social history was significant in that she smoked two to three cigarettes daily. Her height was 165 cm (5 ft 5 in.) and she weighed 74.25 kg (165 lb).

Her medicl history was significant only for her most recent pregnancy, which had been complicated by early vaginal bleeding, a relatively sedentary lifestyle, and a weight gain of 18 kg (40 lb). She had had a spontaneous vaginal delivery complicated by a hemorrhage in the third stage of labor. The hemorrhage was controlled with uterine message, intravenous oxytocin, and oral methylergonovine maleate.

The patient was admitted to the hospital with the diagnosis of a probable deep venous thrombosis (DVT) for which she received an intravenous bolus of 5000 U of heparin followed by 1000 U per hour intravenously. An impedance plethysmograph subsequently documented a DVT in her right leg. An electrocardiogram showed inverted T waves in leads [V.sub.1] through [V.sub.3], so a ventilation-perfusion (V/O) scan was ordered. On her way to the nuclear medicine department to have the test, the patient began to experience pleuritic chest pain on the left side and diaphoresis. A pulmonary embolism was subsequently documented on the V/Q scan (Figures 1 and 2). The patient received heparin and warfarin during the hospitalization. She was discharged 13 days after admission, given a prescription for warfarin, 7.5 mg daily, and advised to use thromboembolic disease stockings. The patient and her husband chose to use barrier contraceptives until a tubal ligation could be performed.

Discussion

During pregnancy, the elements of Virchow's triad, including stasis, vascular damage, and hyperoagulability, may all be present. [3] Hypercoagulability may result from changes in both the coagulation cascade and the fribrinolytic system. Circulating estrogens induce the hepatic production of procoagulant factors VII, VIII, IX, and X. Increases in the concentrations of prothrombin and fibrinogen may also occur. [4,5] The concentrations of protein C and protein S, inhibitors of the coagulation cascade, may also be reduced. [4]

In the postpartum period, a slow decline in the concentration of estrogen-induced clotting factors is accompanied by the return of normal activity within the fibrinolytic system in the first few days following delivery of the placenta. For some women, however, the changes in the procoagulant factors may persist for at least 7 to 10 days postpartum. [6] During pregnancy, the incidence of thromboembolic disease has been estimated to be as high as 0.15% for superficial thrombophlebitis and 0.36% for deep venous thrombophlebitis. In the postpartum period, because of the thromotic changes described as well as the stasis and the vascular damage following a delivery, the incidence may be substantially greater than that during pregnancy. [3]

Since the introduction of oral contraceptives almost 30 years ago, epidemiologic data on the association between their use and the development of venous thromboembolism have been well documented. [7] The use of oral contraceptives containing less than 100 [microgram] of either ethinyl estradiol or mestranol has approximately one third the risk of thromboembolism that using those products containing 100 [microgram] or more of the estrogen component has. [8] Whether oral contraceptives containing 35 [microgram] or less of the estrogen component definitely are safer, with respect to thromboembolism, than the 50 [microgram] and 80 [microgram] products is unknown because data are conflicting. [8,9] In addition to the dose of the estrogen, progestins such as norethindrone and ethynodiol diacetate have inherent estrogenic activity. It is unknown if triphasic oral contraceptives offer advantages in terms of reduced risk of venous thromboembolism.