Assessment of separate contributions to perinatal mortality of infertilityhistory and treatment: a case-control analysis

Background. Few studies have described the perinatal risks associated with infertility, other than for infertility treated by in-vitro fertilisation o r gamete intrafallopian transfer, The aim of this analysis was to estimate the risks of perinatal death associated with treated and untreated infertil ity. Methods. A population-based case-control study of perinatal deaths was carr ied out in Leicestershire Health District over the period 1990-94, during w hich 60922 babies were delivered. Of these, 567 perinatal deaths were assoc iated with 542 women. 972 mothers were randomly selected as controls. Medic al. obstetric, and social data were collected for cases and controls from t he medical notes and interviews with the women,The relative risks of perina tal death associated with treated and untreated infertility before the inde x pregnancy were estimated as odds ratios by means of unconditional logisti c regression analysis. Findings. 65 (10%) of cases and 34 (3.5%) of the controls had infertility b efore the index pregnancy. History of infertility in the index pregnancy, i rrespective of treatment, increased the risk of perinatal death (odds ratio 2.9 [95% Cl 1.8-4.5]). The population attributable risk fraction for perin atal death related to infertility was 62% (3.4-9.0). 45 (54%) of the deaths , even in the untreated group, were associated with immaturity. Compared wi th women without infertility, women with untreated infertility were at incr eased risk of perinatal death (3.3 [1.6-6.8]). The risk of perinatal death associated with multiple births did not explain this finding. Similarly, tr eated infertility also increased the risk of perinatal death (2.7 [1.5-4.7] ); the risks associated with multiple births explained some, but not all, o f this excess. In Leicestershire, the overall underlying risk of a mother e xperiencing at least one perinatal death over the study was 9.0 per 1000 wo men. For women who experience infertility, this risk increases by about 18 per 1000 (6-30). Interpretation. Counselling for women before any form of infertility treatm ent should include discussion of the risks of perinatal death. Our results would benefit from confirmation. However, we advocate that at antenatal boo king a history of infertility, irrespective of treatment, should be sought, because these women have a significantly increased risk of perinatal death , particularly associated with prematurity.