The relationship between spontaneous and induced abortion and the occurrence of second-trimester abortion in subsequent pregnancies.

Abstract

Listen

Translate article

Abstract In part I of the present paper an analytic review is presented of the literature on the possible harmful influence of a spontaneous or induced abortion on the course of a subsequent pregnancy. Lack of unanimity proved the most striking result of the analysis. One part of the authors concluded to a relationship between second-trimester abortion and a preceding spontaneous or induced abortion, whereas the others reached a negative result. Since it was thought that the design of all the investigations reviewed showed minor or major deficiencies it was decided to formulate the conditions that must be fulfilled in order to be able to draw valid conclusions on the possible relationship between a second-trimester abortion and a preceding spontaneous or induced first-trimester abortion and to carry out a study that fulfilled the necessary criteria. (The authors should like to stress that the conditions formulated can serve as a model for all investigations that aim at studying the possible relationship between a gestational derangement and a specific disturbance occurring during a preceding pregnancy.) The conditions are that a distinct definition of the disturbances and derangements should be given and strictly adhered to; that the index cases and their controls should be consecutively collected from a clearly defined population; that the induced or spontaneous abortion should immediately precede the second-trimester abortion and that the index cases and their controls should be matched as far as possible (pregnancy order, age at parturition, period of parturition) with exclusion of possible other causes of immature delivery (severe congenital malformations, multiple births, intrauterine infection, uterine anomalies) from the index cases and the controls. After completion of the study a posteriori matching should be carried out to establish whether the frequency of other possible relevant factors differed between index pregnancies and controls. The second part of the present study consists of the investigation of all 87 cases of second-trimester abortion (deliveries at a duration of 112–197 days and/or a birth-weight of less than 1000g) that occurred during a 5-yr period (1973–1977) in the Amsterdam department. Of these 87 deliveries 59 belonged to the category in which the outcome of the delivery under investigation was considered to be related to disturbances observed in the pregnancy itself and not to the preceding pregnancy. In 6 cases the second-trimester abortion was preceded by an induced abortion and in 13 cases by a spontaneous abortion. In 19 cases out of the remaining 28 cases an anomaly in the preceding pregnancy was detected. A control group of 56 pregnancies was composed. Each index case was matched with 2 patients with a similar rank of gestation and with the same maternal age. One of these controls had delivered as near as possible prior to the date of immature delivery of the index case and the other as near as possible after that date. In the control group 3 patients had an induced abortion and 8 a spontaneous abortion in the preceding pregnancy. The difference between the index group and the control group is significant ( P Since the possibility had to be taken into account that the relationship between a spontaneous abortion and an induced abortion and the outcome of a subsequent pregnancy are not similar, both groups were separately investigated with the exclusion of the other index cases and their controls. Of 15 second-trimester abortions not preceded by a spontaneous abortion 6 underwent an induced abortion prior to the pregnancy as compared to 3 in the 30 controls ( P 0.04). Of the 22 pregnancies not preceded by an induced abortion, 13 had had a spontaneous abortion prior to the present pregnancy as compared to 8 in the 44 controls ( P 0.003). It is concluded that a relationship, presumably of a cause-effect nature, exists between an induced abortion and a second-trimester abortion in a subsequent pregnancy. The relationship between a spontaneous abortion and a second-trimester abortion in a subsequent pregnancy is far more significant. In the latter cases an inherent fetal, idiopathic wastage syndrome is thought to be present causing both the first- and the second-trimester abortion.