Aaron B. Caughey, MD, MPP, MPH, PhD; Vandana Sundaram, MPH; Anjali J. Kaimal, MD; Allison Gienger, BA; Yvonne W. Cheng, MD, MPH; Kathryn M. McDonald, MM; Brian L. Shaffer, MD; Douglas K. Owens, MD, MS; Dena M. Bravata, MD, MS
The rates of induction of labor and elective induction of labor are increasing. Whether elective induction of labor improves outcomes or simply leads to greater complications and health care costs is commonly debated in the literature.
To compare the benefits and harms of elective induction of labor and expectant management of pregnancy.
MEDLINE (through February 2009), Web of Science, CINAHL, Cochrane Central Register of Controlled Trials (through March 2009), bibliographies of included studies, and previous systematic reviews.
Experimental and observational studies of elective induction of labor reported in English.
Two authors abstracted study design; patient characteristics; quality criteria; and outcomes, including cesarean delivery and maternal and neonatal morbidity.
Of 6117 potentially relevant articles, 36 met inclusion criteria: 11 randomized, controlled trials (RCTs) and 25 observational studies. Overall, expectant management of pregnancy was associated with a higher odds ratio (OR) of cesarean delivery than was elective induction of labor (OR, 1.22 [95% CI, 1.07 to 1.39]; absolute risk difference, 1.9 percentage points [CI, 0.2 to 3.7 percentage points]) in 9 RCTs. Women at or beyond 41 completed weeks of gestation who were managed expectantly had a higher risk for cesarean delivery (OR, 1.21 [CI, 1.01 to 1.46]), but this difference was not statistically significant in women at less than 41 completed weeks of gestation (OR, 1.73 [CI, 0.67 to 4.5]). Women who were expectantly managed were more likely to have meconium-stained amniotic fluid than those who were electively induced (OR, 2.04 [CI, 1.34 to 3.09]).
There were no recent RCTs of elective induction of labor at less than 41 weeks of gestation. The 2 studies conducted at less than 41 weeks of gestation were of poor quality and were not generalizable to current practice.
RCTs suggest that elective induction of labor at 41 weeks of gestation and beyond is associated with a decreased risk for cesarean delivery and meconium-stained amniotic fluid. There are concerns about the translation of these findings into actual practice; thus, future studies should examine elective induction of labor in settings where most obstetric care is provided.
Appendix Table 1.
Appendix Table 2.
Appendix Table 3.
Shown are the percentages of the included studies that did (black bars) and did not (gray bars) fulfill each of the a priori–determined quality criteria. RCT = randomized, controlled trial.
Appendix Table 4.
Appendix Table 5.
Appendix Table 6.
CS = cesarean section; Mgt = management; MSF = meconium-stained fluid; NICHHD = National Institute of Child Health and Human Development; RR = relative risk. Top. Odds ratios and 95% CIs for each of the 8 studies that reported CS rates and the summary (random-effects) odds ratio. Bottom. Odds ratios and 95% CIs for the 6 trials that presented data on meconium-stained fluid.
CS = cesarean section; Mgt = management; NICHHD = National Institute of Child Health and Human Development; RR = relative risk.
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Martin J Quinn
August 18, 2009
Obstetric interventions and gynecological consequences
Aaron B Caughey's comprehensive systematic review concludes that rates of Caesarean section rate are equivalent or lower, for induced labor when appropriate comparisons are engaged (1). He carefully notes that "no studies addressed the risk for hysterectomy, length of labor, evidence of injury to internal organs, or wound complications after elective induction of labor". It is these outcomes at five and ten years that are critical to maternal outcome and for which, no systematic information has existed.
There is an increasing awareness that obstetric events in a womans' first labor determine her subsequent gynaecological outcomes. The initial evidence arises from studies in the 1950's from St Louis, Missouri, which related chronic pelvic pain to difficulties in labor (2). More recent evidence offers the view that intrapartum injuries to autonomic nerves contributes to the development of endometriosis, adenomyosis and leiomyomas (3, 4). In a prospective study of 2240 nulliparous women over four years in the Avon Longitudinal Study of Pregnancy and Childbirth cohort, our group find worse gynaecologic outcomes at 47 months follow-up for almost all intrapartum interventions including induction of labor.
One proposed mechanism of injury to pelvic autonomic nerves is engaged by the injuries to uterosacral ligaments following excessive uterine activity that complicates 2-5% of induced labours. Uterosacral ligaments contain branches of the inferior hypogastric plexus that deliver autonomic nerves to the uterus and vagina. Excessive uterine activity results in attenuation, or even avulsion, of the uterosacral ligaments with widespread reinnervation at the site of the injury presenting with chronic pelvic pain 5-10 years later (3-5). Uterosacral "defects" are not recognised in the clinical literature though vaginal, levator and neurologic injuries have been recorded as adverse consequences of vaginal delivery.
Selective, though carefully qualified, evidence may be useful with respect to specific outcomes such as Caesarean section though such information is often reported in a less-qualified fashion. That gynaecologic outcomes are a consequence of intrapartum events is a nettle that the specialty needs to grasp before the medicolegal community takes too close an interest.
(1) Caughey AB, Sundaram V; Kaimal AJ, Gienger A, Cheng YWW, McDonald KM, Shaffer BL, Owens DK, Bavata DM. Systematic Review: Elective Induction of Labor Versus Expectant Management of Pregnancy. Ann Int Med 2009; 151(4): 252-263.
(2) Allen WM, Masters WH. Traumatic laceration of uterine support. Am J Obstet Gynecol 1955; 70:500-513.
(3) Quinn M Endometriosis; an elusive epiphenomenon ? J Obstet Gynaecol October, 2009 (in press)
(4) Quinn M, Kirk N. Uterosacral nerve fibre proliferation in parous endometriosis. J Obstet Gynaecol 2004; 24:189-90.
(5) Atwel GSS, Duplessis D, Armstrong GR, Slade RJ, Quinn MJ. Uterine innervation after hysterectomy for chronic pelvic pain with, or without, endometriosis. Am J Obstet Gynecol 2005: 193:1658-1663.
Caughey AB, Sundaram V, Kaimal AJ, Gienger A, Cheng YW, McDonald KM, et al. Systematic Review: Elective Induction of Labor Versus Expectant Management of Pregnancy. Ann Intern Med. ;151:252–263. doi: 10.7326/0003-4819-151-4-200908180-00007
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Published: Ann Intern Med. 2009;151(4):252-263.
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