Risk factors for abnormal umbilical cord insertions among term singleton art pregnancies

Abstract

The placenta with velamentous umbilical cord insertion (VCI) is a rare pathologic condition that is supposed to increase the risk of perinatal complications. The reported adverse outcomes include fetal growth restriction, non-reassuring fetal status requiring emergency Cesarean section, fetal exsanguination due to the rupture of vasa previa, and cerebral palsy. We reported on a study, emphasizing a higher incidence of the placenta accompanied by VCI in ART pregnancies when compared with non-ART cases, at the 70th ASRM Annual Meeting. In this research, we examined the ART-conceived cases closely for the purpose of identifying the ART-associated risk factors that might affect the incidence of the placenta with VCI. Retrospective cohort study and comparative analysis. We reviewed the records of 427 consecutive singleton, term labor and delivery ART-conceived cases from January 2011 to April 2016. Information about maternal age, obstetric history, details of ART treatment, mode of delivery, and insertion site of the umbilical cord was all collected from their medical records. Our study population was divided into two categories as follows: cases with VCI (Group A: n=23), and cases without VCI (Group B: n=404). Odds ratios for VCI, 95% confidence intervals (CI), and significance of the odds ratio were calculated according to ART-related variables (i.e., fertilization method (conventional-IVF vs. ICSI), type of embryo (fresh vs. frozen-thawed), embryo transfer timing (day 2-3 early-cleavage stage embryo vs. day 5-6 blastocyst), and fetal sex), using multivariate logistic regression. Maternal basal characteristics and odds ratios were shown in the table below. The incidence of VCI in our study population was 5.4% (23/427). The rate of delivery necessitating emergency C-section or operative vaginal delivery in Group A (14/23, 61%) was much higher than in Group B (138/404, 34%). Blastocyst transfer and female fetus significantly increased the likelihood of developing the placenta with VCI. Fertilization method and type of embryo did not affect the incidence of the placenta with VCI.Tabled 1Baseline characteristics and adjusted odds ratio(aOR) for velamentous umbilical cord insertionGroup A (cases with VCI: n=23)Group B (cases without VCI: n=404)aOR for VCI (95% CI, P value)Maternal age35.9±3.835.5±3.61.03 (0.91 - 1.16, 0.66)Parity (primipara / multipara)20 / 3302 / 1021.00 (reference) / 0.40 (0.09 - 1.23, 0.15)c-IVF / ICSI5 / 18143 / 2611.00 / 1.96 (0.76 - 6.05, 0.19)Fresh / Frozen-thawed7 / 16136 / 2681.00 / 1.25 (0.52 - 3.34, 0.63)Early cleavage / Blastocyst1 / 22117 / 2871.00 / 10.23 (2.09 - 184.78, 0.02*)Male / Female5 / 18200 / 2041.00 / 3.48 (1.35 - 10.71, 0.02*)[Note of the table above: Data are mean±SD or number of subjects. Odds ratios were all adjusted for maternal age and parity. *: P<0.05 was considered statistically significant.] Open table in a new tab [Note of the table above: Data are mean±SD or number of subjects. Odds ratios were all adjusted for maternal age and parity. *: P<0.05 was considered statistically significant.] As VCI often brings about serious obstetric complications, ART pregnancies achieved by blastocyst transfer and/or of female fetus are optimal candidates for checking up on and identifying the umbilical cord insertion site more proactively during routine obstetric ultrasound examinations.