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Induced Abortions Linked to Preterm Delivery


 

From the Annual Meeting of the Society of Obstetricians and Gynaecologists of Canada

Major Finding: A history of one or more abortions was associated with a twofold increase in preterm delivery at less than 24 weeks' gestation.

Data Source: A study of 3,138 women who had one or more therapeutic abortions who underwent a subsequent delivery of a live singleton or multiples and 14,778 women who had no history of abortion and who gave birth at the hospital during the same period.

Disclosures: None was reported.

MONTREAL – Women with a history of one or more therapeutic abortions have double the risk of preterm delivery before 24 weeks' gestation in a subsequent pregnancy, compared with those with no abortion history, a study by researchers from McGill University in Montreal has shown.

“The implications are that abortions can lead to cervical insufficiency, and that public health efforts should aim at prevention through early counseling and provision of effective contraception for all women,” said the principal investigator, Dr. Haim Abenhaim, obstetrician/gynecologist at Montreal's SMBD Jewish General Hospital, which is part of McGill University.

The retrospective study, presented by Dr. Ghislain Hardy at the meeting, looked at all women who had undergone an induced abortion and subsequent delivery of a live singleton or multiples birth at a single, tertiary care institution between 2001 and 2006.

A total of 2,276 women had undergone one abortion, and 862 had undergone two or more. These women were compared with 14,778 women who had no history of abortion and who gave birth at the hospital during the same period.

Most of the therapeutic abortions [TABs] were first-trimester dilation and curettage, Dr. Abenhaim said in an interview. “For a therapeutic abortion (voluntary, for a normal pregnancy), the most common approach is a D&C [that is, surgical], while a medical approach is the more common for an arrested pregnancy.”

After adjustment for age, smoking, alcohol consumption, body mass index, marital status, and education, the investigators found that a history of one or more abortions was associated with a twofold increase in preterm delivery at less than 24 weeks. In addition, women with a history of abortion were more likely to require tocolysis – and this became statistically significant with two or more abortions (odds ratio, 1.42). Dr. Abenhaim did not present absolute numbers and did not respond to requests to acquire this information.

“The association between therapeutic abortions and prematurity has been seen before; however, our study was different in that it tried to examine the relationship between TABs and the timing of prematurity,” explained Dr. Abenhaim. “Prematurity caused by a cervical insufficiency is believed to occur earlier than prematurity which is considered idiopathic or infectious. Our results suggest that the effect of TABs is more consistent with early/cervical insufficiency–type preterm births.”

The findings are potentially important, said Dr. Anthony Armson, who chaired the session in which the study was presented. However, they should be interpreted with caution, especially since the study has not yet been published, said the professor and head of obstetrics and gynecology at Dalhousie University in Halifax, N.S.

“Certainly there has been evidence to support [the risk of] two or more therapeutic abortions in the first trimester, or any in the second-trimester – but that observation has not always been supported,” he said in an interview. “A number of investigators in the '80s and '90s, including myself, tried to come up with a risk-scoring algorithm to establish what factors were important in preterm birth. But in the vast majority, one therapeutic abortion did not come up as a risk factor.”

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