Missing abortion stratification adds to confusion

EDITOR—The objective of Nybo Andersen et al's study of fetal loss was to measure the age related risk of fetal loss “taking into account a woman's reproductive history.”1 To this end the authors stratified the women according to parity and previous spontaneous abortions but inexplicably omitted stratification by induced abortions. Their only reported use of their complete data on induced abortions was to deduct from the count of fetal loss any miscarriages that occurred before an intended abortion.

The effect of elective abortion on future reproductive health is contentious. Some investigators have found statistical associations between induced abortion and subsequent miscarriages and ectopic pregnancies.2 Others have reported that there is no significant association between abortion and either of these events.3 Colleagues of the authors at the Danish Epidemiology Science Centre, using many of the same data, have recently reported a strong association between induced abortion and subsequent preterm and post-term deliveries, a finding that adds to concerns that induced abortion may degrade reproductive health.4

Numerous studies have shown that abortion is closely associated with other confounding factors, such as smoking, alcohol, and drug use; promiscuity; and venereal disease (citations to several of these studies are included in my rapid response to Nybo Andersen et al's study on bmj.com5). These behaviours may help women to cope with unresolved anxiety and depression after abortion. Women with a history of abortion are especially likely to persist in using tobacco, alcohol, and illegal drugs …