American Journal of Obstetrics & Gynecology Mfm最新文献

Background: Spontaneous labor and birth peak during the late evening and early morning hours, indicating a circadian influence on parturition. However, the effect of the time-of-day of labor induction (TOI) on labor duration and obstetric outcomes remains unexplored. We hypothesize that the time-of-day of labor induction will impact induction of labor (IOL) duration and the risk of cesarian section.

Objective: To determine whether TOI impacts IOL duration and delivery outcomes in term pregnancies, and whether maternal characteristics such as body mass index (BMI) and parity modulate this effect.

Study design: This retrospective cohort study analyzed 3,363 term pregnant subjects who underwent induction at a single U.S. hospital between 2019 and 2022. Time-of-induction was defined as the time of administration of the first cervical ripening agent or synthetic oxytocin (i.e., Pitocin). IOL duration was calculated as the time from induction to delivery. Multivariable analyses, survival models, and circadian rhythm analyses were performed to evaluate associations between TOI, IOL duration, cesarean delivery, and neonatal outcomes.

Results: IOL duration followed a significant circadian rhythm (p<0.05, Lomb-Scargle), with a gradual lengthening in IOL duration when induction was initiated later in the day, peaking at 23:00 hours (average IOL duration of 21.0 hours) as compared to induction at 05:00 hours (average IOL duration of 14.8 hours, p<0.01, Kruskal-Wallis test). Subjects induced during the early morning had up to 6 hours shorter labor compared to those induced in the late evening (p<0.01). The optimal time-of-day to initiate labor induction was influenced by BMI and parity with significant differences in probability of giving birth resulting from the time-of-day labor was induced for nulliparous obese (p<0.05, Two-way ANOVA), and parous obese subjects (p<0.05). Time-of-induction was associated with reduced cesarean delivery rates and did not impact rates of NICU admissions or adverse neonatal outcomes.

Conclusion: The time of day of initiation of labor induction influenced IOL duration, with the shortest duration when induced during early morning hours. No increase in adverse maternal and fetal outcomes was identified when controlling for time-of-day of labor induction. The optimal time-of-day to induce labor is influenced by BMI and parity and should be considered when performing this common obstetric intervention.

Background: Antenatal diagnosis of placenta accreta spectrum (PAS) is imperfect with cases undiagnosed prior to delivery resulting in suboptimal outcomes. Currently, there is no agreed upon standardized protocol for risk-stratification of PAS. Most patients are identified in the 2^nd or 3^rd trimester, although findings on first trimester ultrasound may be associated with development of PAS. At present, there is no recommended risk stratification algorithm that applies first trimester findings in a systematic manner with outcome data.

Objective: Development of a risk stratification algorithm for PAS in the first trimester of pregnancy in symptomatic patients STUDY DESIGN: A retrospective observational study of first trimester sonograms between January 2021 and February 2024 compared the performance of low implantation with prior cesarean delivery (CD) to a newly developed risk stratification algorithm. Low implantation was diagnosed when the distance of the inferior border of trophoblastic change or the border of the gestational sac was 5 centimeters (cm) or less from the external os on ultrasound imaging. Pregnancies were analyzed based on gestational sac location (<10 weeks) or decidual basalis (≥10 weeks) and smallest myometrial thickness (SMT) to assess PAS risk. Test parameters of low implantation and the new risk stratification algorithm were calculated. Inter-reader variability of the SMT measurement with kappa statistic and McNemar's test was performed.

Results: Of 6213 patients with first trimester sonography and known delivery outcome, 1252 had a prior CD and 257/1252 (20.5%) of these had low implantation. Of 12 patients with confirmed PAS, 10 had low implantation. The sensitivity, specificity, and positive predictive value (PPV) of low implantation for PAS were 83.3%, 80%, and 3.8% respectively. Of these 257, 245 had adequate images to test the new algorithm. Of 245, 10 (4.1%) screened positive. PAS was confirmed in 9 of 10 with positive screens, with sensitivity, specificity, and PPV for PAS of 90%, 99.6%, and 90% respectively. Weighted kappa statistic of 0.65 (95% CI: 0.46-0.83) and McNemar's test p-value of 0.24 indicated substantial agreement.

Conclusion: Our first trimester risk stratification algorithm was more sensitive and specific for PAS with higher PPV when compared to low implantation with prior CD. Inter-reader agreement was also high. Future prospective studies to validate this risk stratification algorithm are needed.

Background: A false-positive cell-free DNA prenatal screening result may arise from confined placental mosaicism, however, the frequency and obstetrical ramifications of such cases are poorly understood.

Objective: This study aimed to assess the prevalence of confined placental mosaicism among pregnancies with false-positive cell-free DNA results and the associated obstetrical outcomes.

Study design: This was a prospective, matched-cohort study with a 1:2 ratio of cases with false-positive cell-free DNA results and controls with low-risk cell-free DNA results that were matched by maternal age and body mass index. Participants were recruited between November 2022 and March 2025 at Monash Health and Monash Ultrasound for Women in Melbourne, Australia. Cytogenetic testing was conducted on 4 biopsies per placenta to investigate confined placental mosaicism. The cases and matched controls were compared using trio matching identifiers as random effect in conditional logistic regression and linear mixed-effects modelling.

Results: A total of 60 cases with false-positive cell-free DNA results were matched with 120 controls. Confined placental mosaicism was observed in 20 of the 60 cases (33.3%) and in none of the controls. The prevalence of confined placental mosaicism was highest among those with rare autosomal trisomy (57.9%; 11/19) and monosomy X (75.5%; 3/4) results. Confined placental mosaicism was also observed following common autosomal trisomy results (21.4%; 3/14) and subchromosomal copy number variants (15.8%; 3/19). The median birth weight percentile was significantly lower among instances of confirmed confined placental mosaicism (20.1; interquartile range, 9.9-48.5) than among matched controls (43.5; interquartile range, 17.1-66.1; P=.049); however, there were no statistically significant increases in small-for-gestational-age neonates or other adverse pregnancy outcomes.

Conclusion: Confined placental mosaicism is a frequent contributor to false-positive cell-free DNA results, most often for monosomy X and rare autosomal trisomy results. Although the birth weight median percentiles were lower, the outcomes of cell-free DNA-detected confined placental mosaicism in this average-risk cohort were predominantly favorable. VIDEO ABSTRACT.