Assisted reproductive technology and prolonged third stage of labour: a multicentre study in Japan

Abstract

Research QuestionWe investigated the risk factors for prolonged third stage of labour, which is closely related to postpartum haemorrhage, and evaluated the impact of assisted reproductive technology (ART) on the third stage of labour using multicentre clinical data. DesignThe clinical data of women who delivered vaginally at term at 12 primary maternity hospitals in Japan between 2012 and 2018 (n = 25,336) were obtained. Of these, 1,148 (4.5%) and 2,246 (8.9%) women conceived through ART and non-ART fertility treatments, respectively. Univariable and multivariable regression analyses were conducted to evaluate the risk of a prolonged third stage of labour (defined as ≥ 20 min). We then evaluated the adjusted odds ratios (aORs) of a prolonged third stage of labour stratified by the type of ART, with natural conception as a reference. ResultsMultivariable analysis showed that ART pregnancy (aOR 4.38 [95% confidence interval: 3.12–6.15]), a history of abortion (1.40 [1.06–1.84]), and a prolonged labour (1.52 [1.09–2.12]) were identified as independent risk factors. Among the types of ART procedures, frozen embryo transfer (FET), FET in a hormone replacement cycle (HRC-FET), and blastocyst-stage embryo transfer were significantly associated with a prolonged third stage of labour (aOR 4.07 [2.75–6.04], 4.11 [2.58–6.57], and 2.13 [1.15–3.95], respectively). No significant difference was observed in the duration of third stage of labour between natural conception and non-ART fertility treatment (p = 0.61). ConclusionART pregnancy, particularly FET, HRC-FET, and blastocyst-stage embryo transfer, was a significant risk factor for a prolonged third stage of labour.