Reassessing the labor curve in nulliparous women.

OBJECTIVES: Our purpose was to examine the pattern of labor progression in nulliparous parturients in contemporary obstetric practice. STUDY DESIGN: We extracted detailed labor data from 1329 nulliparous parturients with a term, singleton, vertex fetus of normal birth weight after spontaneous onset of labor. Cesarean deliveries were excluded. We used a repeated-measures regression with a 10th-order polynomial function to discover the average labor curve under contemporary practice. With use of an interval-censored regression with a log normal distribution, we also computed the expected time interval of the cervix to reach the next centimeter, the expected rate of cervical dilation at each phase of labor, and the duration of labor for fetal descent at various stations. RESULTS: Our average labor curve differs markedly from the Friedman curve. The cervix dilated substantially slower in the active phase. It took approximately 5.5 hours from 4 cm to 10 cm, compared with 2.5 hours under the Friedman curve. We observed no deceleration phase. Before 7 cm, no perceivable change in cervical dilation for more than 2 hour was not uncommon. The 5th percentiles of rate of cervical dilation were all below 1 cm per hour. The 95th percentile of time interval for fetal descent from station +1/3 to +2/3 was 3 hours at the second stage. CONCLUSION: Our results suggest that the pattern of labor progression in contemporary practice differs significantly from the Friedman curve. The diagnostic criteria for protraction and arrest disorders of labor may be too stringent in nulliparous women.

U.S. national trends in labor induction, 1989-1998.

OBJECTIVE: To examine the epidemiology of labor induction in the United States. STUDY DESIGN: We used U.S. natality data from 1989 to 1998 and examined the rate of labor induction by year, geographic region, maternal characteristics and pregnancy complications. RESULTS: Between 1990 and 1998, the rate of labor induction increased from 9.5% to 19.4% of all births nationwide. However, the induction rate varied widely by state. White race, higher education and early initiation of prenatal care were associated with a higher rate of induction. For all gestational ages, a significantly increased induction rate occurred during the study period. The increase for clinically indicated induction was significantly slower than the overall increase, suggesting that elective induction has risen much more rapidly. CONCLUSION: The rate of induction of labor more than doubled in the U.S. nationwide in the decade from 1989 to 1998. The increased use of labor induction may be attributable to both clinically indicated and elective induction.

Risk factors for early cytologic abnormalities after loop electrosurgical excision procedure.

OBJECTIVE: To evaluate risk factors for early cytologic abnormalities and recurrent cervical dysplasia after loop electrosurgical excision procedure (LEEP). METHODS: A retrospective analysis was performed of all pathology records for LEEPs performed at our institution from January 1996 through July 1998. Follow-up cytology from 2 through 12 months after LEEP was reviewed. Patients with abnormal cytology were referred for further colposcopic evaluation. Statistical analysis using chi2 test for trend, proportional hazards model test, Fisher exact tests, and life table analysis were performed to identify risk factors for early cytologic abnormalities after LEEP and to determine relative risk of recurrent dysplasia. RESULTS: A total of 298 women underwent LEEP during the study period, and 29% of these had cytologic abnormalities after LEEP. Grade of dysplasia, ectocervical marginal status, endocervical marginal status, and glandular involvement with dysplasia were not found to be independent risk factors for early cytologic abnormalities. However, when risk factors were analyzed cumulatively, the abnormal cytology rate increased from 24% with no risk factors to 67% with three risk factors present (P =.037). Of patients with abnormal cytology after LEEP, 40% developed subsequent dysplasia, and the mean time to diagnosis was approximately 6 months. The relative risk of subsequent dysplasia ranged from a 20% increase to twice the risk if post-LEEP cytology was low-grade squamous intraepithelial lesion or high-grade squamous intraepithelial lesion, respectively. CONCLUSION: Based on these results, consideration should be given for early colposcopic examination of patients who have evidence of marginal involvement or endocervical glandular involvement with dysplasia. These patients are at increased risk for abnormal cytology and recurrent dysplasia. This initial visit should occur at 6 months, as the mean time to recurrence of dysplasia was 6.5 months.