Reduced live birth rates after embryo transfer in patients with prior cesarean delivery: A retrospective cohort study.

OBJECTIVE: To evaluate whether live birth rates following first embryo transfer (ET) among patients after cesarean delivery are lower compared to patients with only prior vaginal delivery. STUDY DESIGN: Retrospective cohort study including patients with prior delivery who underwent first subsequent embryo transfer (fresh or frozen) between January 2013 and September 2019. The primary outcome was live birth rate among patients with at least one prior cesarean delivery compared to vaginal delivery only. Secondary outcomes included positive serum hCG, clinical intrauterine pregnancy and miscarriage rates. We performed a subgroup analysis with the cesarean delivery group based on labour status at the time of delivery. We fit a multivariable log-binomial regression model. RESULTS: Total of 962 patients met inclusion criteria: 351 in the cesarean delivery group and 611 in the vaginal delivery group. Live birth rate was significantly lower in the cesarean delivery group compared to vaginal delivery group at 30.0% vs 36.9% [aRR 0.81, 95% CI 0.67-0.98]. We also found lower positive hCG [aRR 0.82, 95% CI 0.72-0.94] and clinical pregnancy [aRR 0.85, 95% CI 0.73-0.99]. There was no significant difference in miscarriage rate. A subgroup analysis within the cesarean delivery group in active labour demonstrated significantly lower live birth rates compared to the vaginal delivery group [aRR 0.67, 95% CI 0.49-0.92]. CONCLUSIONS: Live birth rates following first ET were significantly lower after cesarean delivery compared to vaginal delivery. These findings may be largely attributable to a subgroup of patients with prior cesarean delivery in active labour who may be at particular risk of reduced live birth rates after ET.

Flexible and extended dosing of nicotine replacement therapy or varenicline in comparison to fixed dose nicotine replacement therapy for smoking cessation: rationale, methods and participant characteristics of the FLEX trial.

Quitting smoking is the single most effective strategy to reduce morbidity and premature mortality in smokers. Research has demonstrated the effectiveness of pharmacotherapy in smoking cessation, but few studies have directly compared varenicline and monotherapy nicotine replacement therapy (NRT) and none have examined varenicline and combinations of NRT products. The majority of smoking cessation trials involve carefully circumscribed populations, making their results less generalizable to those with severe medical conditions or psychiatric comorbidities. This paper reports on the rationale, methodology and participant characteristics of a randomized controlled trial designed to: (1) determine which pharmacotherapy - NRT, long term combinations of NRT, or varenicline - is most effective in achieving abstinence; (2) investigate the incidence of neuropsychiatric symptoms among participants over the course of their quit attempt; and (3) assess whether there is a significant difference in the incidence of neuropsychiatric symptoms in those receiving differing pharmacotherapies, and between those with and without psychiatric illnesses. The primary outcome was carbon monoxide confirmed abstinence from weeks 5-52 following a target quit date. Secondary outcomes included neuropsychiatric (i.e., depression, suicidal ideation, anxiety, anger) and withdrawal symptoms. Smokers (N=737) were randomly assigned to one of three treatment conditions, and were scheduled to attend 8 follow-up appointments over 12 months. All participants received 6-15 minute practical counseling sessions with nurse counselors experienced in treating tobacco dependence. We expect that the results will lead to an enhanced understanding of the efficacy of these pharmacotherapies, including those with a history of psychiatric illness.