Comparison of uterine artery Doppler measurements at 6 weeks of pregnancy after IVF between pregnancies that resulted in miscarriage and ongoing pregnancies

Objective To compare uterine artery pulsatility index (UTPI) at 6 weeks of pregnancy following in vitro fertilization (IVF) and embryo transfer (ET) between clinical pregnancies that resulted in a miscarriage and those that were ongoing beyond 12 weeks. Methods A prospective observational study was conducted in an IVF unit at Prince of Wales Hospital, Hong Kong, between December 1, 2017 and December 31, 2019. UTPI was measured at 6 weeks of pregnancy among women who conceived following IVF/ET. Results Among 153 participants, 22 (14.4%) had a miscarriage whereas 131 (85.6%) had an ongoing pregnancy beyond 12 weeks. Median UTPI in pregnancies that ended in a miscarriage was significantly lower than those that progressed beyond 12 weeks (2.1, IQR 1.9–2.4 vs 2.50, IQR 2.2–2.9, respectively; P <0.001). The likelihood of the pregnancy ending in a miscarriage when the UTPI was above the 75th percentile (>2.9), between the 25th–75th percentiles (2.2–2.9), and below the 25th percentile (<2.2) was 0%, 13.2%, and 27.7%, respectively ( P =0.001). Conclusions IVF pregnancies that resulted in a miscarriage were associated with reduced resistance to uterine artery blood flow at 6 weeks of pregnancy.