Risk of Expectant Management and Optimal Timing of Delivery in Low-Risk Term Pregnancies: A Population-Based Study

Abstract

Objective The benefits of the 39-week rule have been questioned and concerns of increased stillbirth after adoption of this rule have been raised. Whether expectant management risks outweigh the benefits of awaiting 39 weeks has not been studied. We analyze the risks of expectant management at term and the optimal timing for delivery.

Study Design All U.S. nonanomalous singleton term deliveries in 2013 were selected, excluding diabetes/hypertension, and low birth weight. Maternal/neonatal complications and stillbirth/infant death were compared among expectant management versus deliveries at each term gestational age. Logistic regression was used to calculate adjust odds ratios of complications according to delivery plan at each gestational age.

Results From approximately 3 million deliveries, maternal complications during expectant management were lower at early term, and became higher at 39 weeks, relative risk [RR] (95% confidence interval [CI]) = 1.18 (1.16–1.19). Neonatal complications during expectant management were lower during early term, and became higher at ≥39 weeks, RR (95% CI) = 1.09 (1.08–1.09). The risk of perinatal mortality in the expectant management group was lower during early term, and became higher at ≥39 weeks, 18.93 (17.83–20.10) versus 17.37 (16.61–18.16), p = 0.010.

Conclusion Complications during expectant management occurring while awaiting full term do not outweigh the benefits of better outcomes from reaching 39 weeks. However, extending beyond 39 weeks may put these pregnancies at an increased risk.

Keywords

obstetric - delivery - pregnancy - complications - newborn - stillbirth - infant mortality

• References

• 1 Spong CY. Defining “term” pregnancy: recommendations from the Defining “Term” Pregnancy Workgroup. JAMA 2013; 309 (23) 2445-2446
• 2 ACOG Committee Opinion No 579: definition of term pregnancy. Obstet Gynecol 2013; 122 (05) 1139-1140
• 3 American College of Obstetricians and Gynecologists Committee on Obstetric Practice Society for Maternal-Fetal Medicine. Committee Opinion No. 573: magnesium sulfate use in obstetrics. Obstet Gynecol 2013; 122 (03) 727-728
• 4 Main EK. New perinatal quality measures from the National Quality Forum, the Joint Commission and the Leapfrog Group. Curr Opin Obstet Gynecol 2009; 21 (06) 532-540
• 5 Vilchez G, Hoyos LR, Maldonado MC, Lagos M, Kruger M, Bahado-Singh R. Risk of neonatal mortality according to gestational age after elective repeat cesarean delivery. Arch Gynecol Obstet 2016; 294 (01) 77-81
• 6 Vilchez GA, Dai J, Hoyos LR, Chelliah A, Bahado-Singh R, Sokol RJ. Optimal timing for term delivery of twin pregnancies: a population-based study. Am J Perinatol 2015; 32 (05) 487-496
• 7 Ehrenthal DB, Hoffman MK, Jiang X, Ostrum G. Neonatal outcomes after implementation of guidelines limiting elective delivery before 39 weeks of gestation. Obstet Gynecol 2011; 118 (05) 1047-1055
• 8 Joseph KS, D'Alton M. Theoretical and empirical justification for current rates of iatrogenic delivery at late preterm gestation. Paediatr Perinat Epidemiol 2013; 27 (01) 2-6
• 9 Mandujano A, Waters TP, Myers SA. The risk of fetal death: current concepts of best gestational age for delivery. Am J Obstet Gynecol 2013; 208 (03) 207.e1-207.e8
• 10 Nicholson J, Kellar L, Ahmad S. , et al. A multi-state analysis of early-term delivery trends and the association with term stillbirth trends in stillbirth by gestational age in the United States, 2006-2012 stillbirth and the 39-week rule: can we be reassured?. Obstet Gynecol 2016; 127 (04) 802-803
• 11 Benedetti TJ, Cawthon L, Thompson J. Neonatal outcomes after implementation of guidelines limiting elective delivery before 39 weeks of gestation. Obstet Gynecol 2012; 119 (03) 656-657 , author reply 657
• 12 Oshiro B, Branch W, Main E. Neonatal outcomes after implementation of guidelines limiting elective delivery before 39 weeks of gestation. Obstet Gynecol 2012; 119 (03) 656 , author reply 657
• 13 Tzur T, Weintraub AY, Sheiner E, Wiznitzer A, Mazor M, Holcberg G. Timing of elective repeat caesarean section: maternal and neonatal morbidity and mortality. J Matern Fetal Neonatal Med 2011; 24 (01) 58-64
• 14 Glantz JC. Term labor induction compared with expectant management. Obstet Gynecol 2010; 115 (01) 70-76
• 15 Cheng YW, Kaimal AJ, Snowden JM, Nicholson JM, Caughey AB. Induction of labor compared to expectant management in low-risk women and associated perinatal outcomes. Am J Obstet Gynecol 2012; 207 (06) 502.e1-502.e8
• 16 Darney BG, Snowden JM, Cheng YW. , et al. Elective induction of labor at term compared with expectant management: maternal and neonatal outcomes. Obstet Gynecol 2013; 122 (04) 761-769
• 17 Palatnik A, Grobman WA. Induction of labor versus expectant management for women with a prior cesarean delivery. Am J Obstet Gynecol 2015; 212 (03) 358.e1-358.e6
• 18 Salemi JL, Pathak EB, Salihu HM. Infant outcomes after elective early-term delivery compared with expectant management. Obstet Gynecol 2016; 127 (04) 657-666
• 19 Nicholson JM. The 39-week rule and term stillbirth: beneficence, autonomy, and the ethics of the current restrictions on early-term labor induction in the US. BMC Pregnancy Childbirth 2015; 15 (Suppl. 01) A9
• 20 Myers SA, Waters TP, Dawson NV. Fetal, neonatal and infant death and their relationship to best gestational age for delivery at term: is 39 weeks best for everyone?. J Perinatol 2014; 34 (07) 503-507
• 21 Rosenstein MG, Cheng YW, Snowden JM, Nicholson JM, Caughey AB. Risk of stillbirth and infant death stratified by gestational age. Obstet Gynecol 2012; 120 (01) 76-82
• 22 Greene MF. Making small risks even smaller. N Engl J Med 2009; 360 (02) 183-184
• 23 Vilchez GA, Dai J, Hoyos LR, Gill N, Bahado-Singh R, Sokol RJ. Labor and neonatal outcomes after term induction of labor in gestational diabetes. J Perinatol 2015; 35 (11) 924-929
• 24 Reddy UM, Ko CW, Willinger M. Maternal age and the risk of stillbirth throughout pregnancy in the United States. Am J Obstet Gynecol 2006; 195 (03) 764-770
• 25 Vilchez G, Chelliah A, Bratley E, Bahado-Singh R, Sokol R. Decreased risk of prematurity after elective repeat cesarean delivery in Hispanics. J Matern Fetal Neonatal Med 2015; 28 (02) 141-145
• 26 Vilchez G, Chelliah A, Argoti P, Jeelani R, Bahado-Singh R. Maternal race and neonatal outcomes after elective repeat cesarean delivery. J Matern Fetal Neonatal Med 2014; 27 (04) 368-371
• 27 Vilchez G, Dai J, Gill N, Lagos M, Bahado-Singh R, Sokol RJ. Racial disparities in the optimal for induction of labor in low-risk term pregnancies: a national population-based study. J Matern Fetal Neonatal Med 2016; 29 (08) 1279-1282
• 28 Vilchez G, Dai J, Lagos M, Sokol RJ. Maternal side effects & fetal neuroprotection according to body mass index after magnesium sulfate in a multicenter randomized controlled trial. J Matern Fetal Neonatal Med 2018; 31 (02) 178-183
• 29 American College of Obstetricians and Gynecologists. Practice bulletin no. 146: Management of late-term and postterm pregnancies. Obstet Gynecol 2014; 124 (2 Pt 1): 390-396
• 30 Clark SL, Miller DD, Belfort MA, Dildy GA, Frye DK, Meyers JA. Neonatal and maternal outcomes associated with elective term delivery. Am J Obstet Gynecol 2009; 200 (02) 156.e1-156.e4
• 31 Tita AT, Lai Y, Landon MB. , et al; Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Maternal-Fetal Medicine Units Network (MFMU). Timing of elective repeat cesarean delivery at term and maternal perioperative outcomes. Obstet Gynecol 2011; 117 (2 Pt 1): 280-286
• 32 Tita AT, Landon MB, Spong CY. , et al; Eunice Kennedy Shriver NICHD Maternal-Fetal Medicine Units Network. Timing of elective repeat cesarean delivery at term and neonatal outcomes. N Engl J Med 2009; 360 (02) 111-120
• 33 MacDorman MF, Reddy UM, Silver RM. Trends in stillbirth by gestational age in the United States, 2006-2012. Obstet Gynecol 2015; 126 (06) 1146-1150
• 34 Zhang X, Kramer MS. Variations in mortality and morbidity by gestational age among infants born at term. J Pediatr 2009; 154 (03) 358-362
• 35 Reddy UM, Bettegowda VR, Dias T, Yamada-Kushnir T, Ko CW, Willinger M. Term pregnancy: a period of heterogeneous risk for infant mortality. Obstet Gynecol 2011; 117 (06) 1279-1287
• 36 Schwenker GL. Why not induce everyone at 39 weeks?. Contemp Ob Gyn 2016 . Available at: http://contemporaryobgyn.modernmedicine.com/contemporary-obgyn/news/why-not-induce-everyone-39-weeks . Accessed January 19, 2018