Background
Conception using assisted reproduction treatments (ART) has been associated with an increased risk of pregnancy complications. It is uncertain if this is caused by ART directly, or is an association of the underlying factors causing infertility.

Aims
We assessed the relationship between assisted conception (AC) and maternal or fetal complications in a large retrospective cohort study. In a nested cohort of women receiving infertility treatment, we determined if such risk rests predominantly with certain causes of infertility.

Materials and Methods
Retrospective database analysis of 50 381 women delivering a singleton pregnancy in four public hospital obstetric units in western Sydney, and a nested cohort of 508 women receiving ART at a single fertility centre, in whom the cause of infertility was known.

Results
A total of 1727 pregnancies followed AC; 48 654 were spontaneous conceptions. Adjusted for age, body mass index and smoking, AC was associated with increased risk of preterm delivery (OR 1.73, 95% CI 1.50–2.02), hypertension (OR 1.55, 95% CI 1.34–1.82) and diabetes (OR 1.51, 95% CI 1.30–1.75). In the nested cohort, ovulatory dysfunction was present in 145 women and 336 had infertility despite normal ovulatory function. Ovulatory dysfunction was associated with increased risk of diabetes (OR 2.94, 95% CI 1.72–5.02) and hypertension (OR 2.40, 95% CI 1.15–5.00) compared to women with normal ovulatory function.

Conclusions
Assisted conception is associated with increased risk of pregnancy complications. This risk appears greatest for women whose underlying infertility involves ovulatory dysfunction. Such disorders probably predispose towards diabetes and hypertension, which is then exacerbated by pregnancy.