Puerperal thromboembolism in relation to the inhibition of lactation by oestrogen therapy.

An analysis was made of 111 consecutive cases of puerperal thromboembolism by the age, parity, mode of delivery, and lactation habit of the women concerned, and the findings were compared with those from control groups.The statistics show that inhibition of lactation by means of ethinyloestradiol is associated with a threefold increase in thromboembolism, although the effect is seen mainly in women who have an operative delivery and who are aged more than 25 years. Among women aged more than 35 years who have an assisted delivery, inhibition of lactation is accompanied by a tenfold increase in the incidence of puerperal thromboembolism.Advancing age and operative intervention (especially caesarean section) are in themselves predisposing causes of deep venous thrombosis and embolism. They can also constitute indications for inhibiting lactation. This makes it difficult to assess whether the relation of thromboembolism to inhibition of lactation or to the administration of oestrogen is real or apparent. Doubts on the interpretation of the findings are raised by the fact that the number of fatal cases of puerperal thromboembolism in England and Wales, and of non-fatal cases in the hospitals under review, has not increased in recent years despite a progressive decrease in breast-feeding. Nevertheless, the evidence suggests that although the administration of ethinyloestradiol is not by itself enough to cause puerperal thromboembolism, it may be a factor which can tip the scales in women who are already predisposed to suffer this condition.Any thromboembolic hazard associated with administration of oestrogens for inhibiting lactation is probably acceptable except in women known to be at special risk by reason of age, operative delivery, obesity, and a past history of thromboembolic episodes.