The impact of assisted reproductive technology and ovulation induction on breech presentation: A whole of population-based cohort study.

AIMS: Multiple studies have suggested a likely association between breech presentation and assisted reproductive technology (ART) for conception. The aims were to determine whether conception via in vitro fertilisation (IVF) and ovulation induction (OI) is associated with fetal malpresentation at birth and to ascertain what mediating factors most significantly contribute to fetal malpresentation. METHODS: This whole-population-based cohort study included 355 990 singleton pregnancies born in Queensland, Australia, between July 2012 and July 2018. Multinomial logistic regression models estimated the adjusted odds of breech, transverse/shoulder and face/brow malpresentations in pregnancies conceived via spontaneous conception, OI (OI group) and IVF with or without intracytoplasmic sperm injection (ART group). RESULTS: After adjustment for potential confounding factors, breech presentation occurred approximately 20% more often in singleton pregnancies conceived via both ART (adjusted odds ratio: 1.20, 95% confidence interval: 1.10-1.30, P < 0.001) and OI (1.21, 95% confidence interval: 1.04-1.39, P < 0.05). No significant associations were observed between the three modes of conception and transverse/shoulder or face/brow presentations. Low birthweight was found to be the most significant mediating factor for breech presentation in pregnancies conceived via ART and OI. CONCLUSIONS: Similar levels of increased odds of breech presentation are present in pregnancies conceived via OI and ART, suggesting a shared underlying mechanism for the aetiology of breech presentation. For women who are considering or have conceived via these methods, counselling with respect to this increased risk is recommended.