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BACKGROUND: Recommendations on preventing the primary cesarean delivery removed the previously defined time limits for latent labor (defined as ending at 6 cm) and urged clinicians to avoid cesarean delivery for labor abnormalities in the latent phase. However, relatively little is known about the implications of labor curve abnormalities from 4 cm to 6 cm and subsequent outcomes. OBJECTIVE: To examine the association between length of time for dilation from 4 cm to 6 cm, delivery outcomes, and maternal and neonatal morbidity. STUDY DESIGN: This is a secondary analysis of a prospective cohort study of patients at ≥37 weeks presenting in spontaneous or induced labor with a non-anomalous living singleton in vertex presentation. Patients with a history of cesarean delivery or who did not achieve 6 cm dilation were excluded. We used interval censored regression to determine the 90(th)percentile for dilation time from 4 cm to 6 cm and used logistic regression to estimate the odds ratios and 95% confidence intervals for adverse outcomes for patients above the these cutoffs percentile compared to those at or below. Analyses were adjusted for obesity, nulliparity, race, hypertension, diabetes, and type of labor (induced vs. spontaneous/augmented). Outcomes included cesarean delivery, maternal morbidity (composite of postpartum fever, wound infection, hemorrhage), and neonatal morbidity (composite of neonatal death, hypothermic therapy, mechanical ventilation, respiratory distress, meconium aspiration syndrome, seizure, or treatment of sepsis). Additionally, we created receiver operator characteristic curves to predict cesarean delivery, and maternal and neonatal morbidity based on time to dilate from 4 cm to 6 cm. The cutoff for time for each outcome was identified using the Youden index to maximize sensitivity and specificity, and test characteristics were computed. RESULTS: There were 7,355 patients eligible for analysis, 728 (10%) had dilation times from 4 cm to 6 cm >10.3 hours, which was the 90(th) percentile, and 6627 (90%) had dilation times ≤ 10.3 hours. Having dilation time from 4 cm to 6 cm above the 90(th) percentile (10.3 h) was associated with cesarean (adjusted odds ratio 2.05 (95% confidence interval 1.67, 2.52)), composite maternal morbidity (adjusted odds ratio 1.48 (95% confidence interval 1.10, 2.00)), and composite neonatal morbidity (adjusted odds ratio 1.92 (95% confidence interval 1.52, 2.4.)). The area under the receiver operator characteristic curve for predicting cesarean delivery was 0.73 (95% confidence interval 0.71, 0.75). The test characteristics for the cutoff of 9.75 h were: sensitivity 68.3% (95% confidence interval 64.8%, 71.7%), specificity 66.2% (95% confidence interval (55.0%, 67.3%), positive predictive value 18.5% (95% confidence interval 17.1%, 20.0%), and negative predictive value 94.9% (95% confidence interval 94.2%, 95.5%). For composite maternal morbidity the cutoff was 6.98 hours and the area under the curve was 0.62 (95% confidence interval 0.59, 0.65), while for composite neonatal morbidity it was 5.5 hours (area under the curve 0.69, 95% confidence interval 0.67, 0.71). CONCLUSIONS: Patients whose dilation time from 4 cm to 6cm exceeds the 90(th) percentile have increased odds of cesarean delivery and postpartum complications. Prolonged dilation time has moderate predictive ability for adverse outcomes. Future studies should investigate at what point, if any, intervention is warranted during this period to reduce these risks.

Background The subdermal contraceptive implant and the 52-mg levonorgestrel intrauterine device are currently Food and Drug Administration approved for 3 and 5 years of use, respectively. Limited available data suggested both of these methods are effective beyond that time. Demonstration of prolonged effectiveness will improve the cost-effectiveness of the device, and potentially patient continuation and satisfaction. Objective We sought to evaluate the effectiveness of the contraceptive implant and the 52-mg hormonal intrauterine device in women using the method for 2 years beyond the current Food and Drug Administration–approved duration. Study Design We initiated this ongoing prospective cohort study in January 2012. We are enrolling women using the contraceptive implant or 52-mg levonorgestrel intrauterine device for a minimum of 3 and 5 years, respectively (started intrauterine device in ≥2007 or implant in ≥2009). Demographic and reproductive health histories, as well as objective body mass index, were collected. Implant users were offered periodic venipuncture for analysis of serum etonogestrel levels. The primary outcome, unintended pregnancy rate, was calculated per 100 woman-years. We analyzed baseline demographic characteristics using χ 2 test and Fisher exact test, and compared serum etonogestrel levels stratified by body mass index using the Kruskal-Wallis test. Results Implant users (n = 291) have contributed 444.0 woman-years of follow-up. There have been no documented pregnancies in implant users during the 2 years of postexpiration follow-up. Calculated failure rates in the fourth and fifth years for the implant are calculated as 0 (1-sided 97.5% confidence interval, 0–1.48) per 100 woman-years at 4 years and 0 (1-sided 97.5% confidence interval, 0–2.65) per 100 woman-years at 5 years. Among 496 levonorgestrel intrauterine device users, 696.9 woman-years of follow-up have been completed. Two pregnancies have been reported. The failure rate in the sixth year of use of the levonorgestrel intrauterine device is calculated as 0.25 (95% confidence interval, 0.04–1.42) per 100 woman-years; failure rate during the seventh year is 0.43 (95% confidence interval, 0.08–2.39) per 100 woman-years. Among implant users with serum etonogestrel results, the median etonogestrel level was 207.7 pg/mL (range 63.8-802.6 pg/mL) at the time of method expiration, 166.1 pg/mL (range 67.9 25.0–470.5 pg/mL) at the end of the fourth year, and 153.0 pg/mL (range 72.1-538.8 pg/mL) at the end of the fifth year. Median etonogestrel levels were compared by body mass index at each time point and a statistical difference was noted at the end of 4 years of use with overweight women having the highest serum etonogestrel (195.9; range 25.0-450.5 pg/mL) when compared to normal (178.9; range 87.0-463.7 pg/mL) and obese (137.9; range 66.0-470.5 pg/mL) women ( P = .04). Conclusion This study indicates that the contraceptive implant and 52-mg hormonal intrauterine device continue to be highly effective for at least 2 additional years of use. Serum etonogestrel evaluation demonstrates median levels remain above the ovulation threshold of 90 pg/mL for women in all body mass index classes.