US term stillbirth rates and the 39-week rule: A cause for concern?

James M. Nicholson, Lisa C. Kellar, Shahla Ahmad, Ayesha Abid, Jason Woloski, Nadine Hewamudalige, George F. Henning, Julianne R. Lauring, Serdar H. Ural, Jerome L. Yaklic

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Background More than a decade ago an obstetric directive called "the 39-week rule" sought to limit "elective" delivery, via labor induction or cesarean delivery, before 39 weeks 0 days of gestation. In 2010 the 39-week rule became a formal quality measure in the United States. The progressive adherence to the 39-week rule throughout the United States has caused a well-documented, progressive reduction in the proportion of term deliveries occurring during the early-term period. Because of the known association between increasing gestational age during the term period and increasing cumulative risk of stillbirth, however, there have been published concerns that the 39-week rule - by increasing the gestational age of delivery for a substantial number of pregnancies - might increase the rate of term stillbirth within the United States. Although adherence to the 39-week rule is assumed to be beneficial, its actual impact on the US rate of term stillbirth in the years since 2010 is unknown. Objective To determine whether the adoption of the 39-week rule was associated with an increased rate of term stillbirth in the United States. Study Design Sequential ecological study, based on state data, of US term deliveries that occurred during a 7-year period bounded by 2007 and 2013. The patterns of the timing of both term childbirth and term stillbirth were determined for each state and for the United States as a whole. Results A total of 46 usable datasets were obtained (45 states and the District of Columbia). During the 7-year period, there was a continuous reduction in all geographic entities in the proportion of term deliveries that occurred before 39 weeks of gestation. The overall rate of term stillbirth, when we compared 2007-2009 with 2011-2013, increased significantly (1.103/1000 vs 1.177/1000, RR 1.067, 95% confidence interval 1.038-1.096). Furthermore, during the 7-year period, the increase in the rate of US term stillbirth appeared to be continuous (estimated slope: 0.0186/1000/year, 95% confidence interval 0.002-0.035). Assuming 3.5 million term US births per year, and given 6 yearly "intervals" with this rate increase, it is possible that more than 335 additional term stillbirths occurred in the United States in 2013 as compared with 2007. In addition, during the 7-year period, there was a progressive shift in the timing of delivery from the 40th week to the 39th week. Absent this confounding factor, the magnitude of association between the adoption of the 39-week rule and the increase in rate of term stillbirth might have been greater. Conclusions Between 2007 and 2013 in the United States, the adoption of the 39-week rule caused a progressive reduction in the proportion of term births occurring before the 39th week of gestation. During the same interval the United States experienced a significant increase in its rate of term stillbirth. This study raises the possibility that the 39-week rule may be causing unintended harm. Additional studies of the actual impact of the adoption of the 39-week rule on major childbirth outcomes are urgently needed. Pressures to enforce the 39-week rule should be reconsidered pending the findings of such studies.

Original languageEnglish (US)
Pages (from-to)621.e1-621.e9
JournalAmerican journal of obstetrics and gynecology
Volume214
Issue number5
DOIs
StatePublished - May 1 2016

Fingerprint

Stillbirth
Term Birth
Pregnancy
Gestational Age
Parturition
Confidence Intervals
Induced Labor
Obstetrics
Pressure

All Science Journal Classification (ASJC) codes

  • Obstetrics and Gynecology

Cite this

Nicholson, J. M., Kellar, L. C., Ahmad, S., Abid, A., Woloski, J., Hewamudalige, N., ... Yaklic, J. L. (2016). US term stillbirth rates and the 39-week rule: A cause for concern? American journal of obstetrics and gynecology, 214(5), 621.e1-621.e9. https://doi.org/10.1016/j.ajog.2016.02.019
Nicholson, James M. ; Kellar, Lisa C. ; Ahmad, Shahla ; Abid, Ayesha ; Woloski, Jason ; Hewamudalige, Nadine ; Henning, George F. ; Lauring, Julianne R. ; Ural, Serdar H. ; Yaklic, Jerome L. / US term stillbirth rates and the 39-week rule : A cause for concern?. In: American journal of obstetrics and gynecology. 2016 ; Vol. 214, No. 5. pp. 621.e1-621.e9.
@article{431820bb8189479ea1fbd1ca316c6b0a,
title = "US term stillbirth rates and the 39-week rule: A cause for concern?",
abstract = "Background More than a decade ago an obstetric directive called {"}the 39-week rule{"} sought to limit {"}elective{"} delivery, via labor induction or cesarean delivery, before 39 weeks 0 days of gestation. In 2010 the 39-week rule became a formal quality measure in the United States. The progressive adherence to the 39-week rule throughout the United States has caused a well-documented, progressive reduction in the proportion of term deliveries occurring during the early-term period. Because of the known association between increasing gestational age during the term period and increasing cumulative risk of stillbirth, however, there have been published concerns that the 39-week rule - by increasing the gestational age of delivery for a substantial number of pregnancies - might increase the rate of term stillbirth within the United States. Although adherence to the 39-week rule is assumed to be beneficial, its actual impact on the US rate of term stillbirth in the years since 2010 is unknown. Objective To determine whether the adoption of the 39-week rule was associated with an increased rate of term stillbirth in the United States. Study Design Sequential ecological study, based on state data, of US term deliveries that occurred during a 7-year period bounded by 2007 and 2013. The patterns of the timing of both term childbirth and term stillbirth were determined for each state and for the United States as a whole. Results A total of 46 usable datasets were obtained (45 states and the District of Columbia). During the 7-year period, there was a continuous reduction in all geographic entities in the proportion of term deliveries that occurred before 39 weeks of gestation. The overall rate of term stillbirth, when we compared 2007-2009 with 2011-2013, increased significantly (1.103/1000 vs 1.177/1000, RR 1.067, 95{\%} confidence interval 1.038-1.096). Furthermore, during the 7-year period, the increase in the rate of US term stillbirth appeared to be continuous (estimated slope: 0.0186/1000/year, 95{\%} confidence interval 0.002-0.035). Assuming 3.5 million term US births per year, and given 6 yearly {"}intervals{"} with this rate increase, it is possible that more than 335 additional term stillbirths occurred in the United States in 2013 as compared with 2007. In addition, during the 7-year period, there was a progressive shift in the timing of delivery from the 40th week to the 39th week. Absent this confounding factor, the magnitude of association between the adoption of the 39-week rule and the increase in rate of term stillbirth might have been greater. Conclusions Between 2007 and 2013 in the United States, the adoption of the 39-week rule caused a progressive reduction in the proportion of term births occurring before the 39th week of gestation. During the same interval the United States experienced a significant increase in its rate of term stillbirth. This study raises the possibility that the 39-week rule may be causing unintended harm. Additional studies of the actual impact of the adoption of the 39-week rule on major childbirth outcomes are urgently needed. Pressures to enforce the 39-week rule should be reconsidered pending the findings of such studies.",
author = "Nicholson, {James M.} and Kellar, {Lisa C.} and Shahla Ahmad and Ayesha Abid and Jason Woloski and Nadine Hewamudalige and Henning, {George F.} and Lauring, {Julianne R.} and Ural, {Serdar H.} and Yaklic, {Jerome L.}",
year = "2016",
month = "5",
day = "1",
doi = "10.1016/j.ajog.2016.02.019",
language = "English (US)",
volume = "214",
pages = "621.e1--621.e9",
journal = "American Journal of Obstetrics and Gynecology",
issn = "0002-9378",
publisher = "Mosby Inc.",
number = "5",

}

Nicholson, JM, Kellar, LC, Ahmad, S, Abid, A, Woloski, J, Hewamudalige, N, Henning, GF, Lauring, JR, Ural, SH & Yaklic, JL 2016, 'US term stillbirth rates and the 39-week rule: A cause for concern?', American journal of obstetrics and gynecology, vol. 214, no. 5, pp. 621.e1-621.e9. https://doi.org/10.1016/j.ajog.2016.02.019

US term stillbirth rates and the 39-week rule : A cause for concern? / Nicholson, James M.; Kellar, Lisa C.; Ahmad, Shahla; Abid, Ayesha; Woloski, Jason; Hewamudalige, Nadine; Henning, George F.; Lauring, Julianne R.; Ural, Serdar H.; Yaklic, Jerome L.

In: American journal of obstetrics and gynecology, Vol. 214, No. 5, 01.05.2016, p. 621.e1-621.e9.

Research output: Contribution to journalArticle

TY - JOUR

T1 - US term stillbirth rates and the 39-week rule

T2 - A cause for concern?

AU - Nicholson, James M.

AU - Kellar, Lisa C.

AU - Ahmad, Shahla

AU - Abid, Ayesha

AU - Woloski, Jason

AU - Hewamudalige, Nadine

AU - Henning, George F.

AU - Lauring, Julianne R.

AU - Ural, Serdar H.

AU - Yaklic, Jerome L.

PY - 2016/5/1

Y1 - 2016/5/1

N2 - Background More than a decade ago an obstetric directive called "the 39-week rule" sought to limit "elective" delivery, via labor induction or cesarean delivery, before 39 weeks 0 days of gestation. In 2010 the 39-week rule became a formal quality measure in the United States. The progressive adherence to the 39-week rule throughout the United States has caused a well-documented, progressive reduction in the proportion of term deliveries occurring during the early-term period. Because of the known association between increasing gestational age during the term period and increasing cumulative risk of stillbirth, however, there have been published concerns that the 39-week rule - by increasing the gestational age of delivery for a substantial number of pregnancies - might increase the rate of term stillbirth within the United States. Although adherence to the 39-week rule is assumed to be beneficial, its actual impact on the US rate of term stillbirth in the years since 2010 is unknown. Objective To determine whether the adoption of the 39-week rule was associated with an increased rate of term stillbirth in the United States. Study Design Sequential ecological study, based on state data, of US term deliveries that occurred during a 7-year period bounded by 2007 and 2013. The patterns of the timing of both term childbirth and term stillbirth were determined for each state and for the United States as a whole. Results A total of 46 usable datasets were obtained (45 states and the District of Columbia). During the 7-year period, there was a continuous reduction in all geographic entities in the proportion of term deliveries that occurred before 39 weeks of gestation. The overall rate of term stillbirth, when we compared 2007-2009 with 2011-2013, increased significantly (1.103/1000 vs 1.177/1000, RR 1.067, 95% confidence interval 1.038-1.096). Furthermore, during the 7-year period, the increase in the rate of US term stillbirth appeared to be continuous (estimated slope: 0.0186/1000/year, 95% confidence interval 0.002-0.035). Assuming 3.5 million term US births per year, and given 6 yearly "intervals" with this rate increase, it is possible that more than 335 additional term stillbirths occurred in the United States in 2013 as compared with 2007. In addition, during the 7-year period, there was a progressive shift in the timing of delivery from the 40th week to the 39th week. Absent this confounding factor, the magnitude of association between the adoption of the 39-week rule and the increase in rate of term stillbirth might have been greater. Conclusions Between 2007 and 2013 in the United States, the adoption of the 39-week rule caused a progressive reduction in the proportion of term births occurring before the 39th week of gestation. During the same interval the United States experienced a significant increase in its rate of term stillbirth. This study raises the possibility that the 39-week rule may be causing unintended harm. Additional studies of the actual impact of the adoption of the 39-week rule on major childbirth outcomes are urgently needed. Pressures to enforce the 39-week rule should be reconsidered pending the findings of such studies.

AB - Background More than a decade ago an obstetric directive called "the 39-week rule" sought to limit "elective" delivery, via labor induction or cesarean delivery, before 39 weeks 0 days of gestation. In 2010 the 39-week rule became a formal quality measure in the United States. The progressive adherence to the 39-week rule throughout the United States has caused a well-documented, progressive reduction in the proportion of term deliveries occurring during the early-term period. Because of the known association between increasing gestational age during the term period and increasing cumulative risk of stillbirth, however, there have been published concerns that the 39-week rule - by increasing the gestational age of delivery for a substantial number of pregnancies - might increase the rate of term stillbirth within the United States. Although adherence to the 39-week rule is assumed to be beneficial, its actual impact on the US rate of term stillbirth in the years since 2010 is unknown. Objective To determine whether the adoption of the 39-week rule was associated with an increased rate of term stillbirth in the United States. Study Design Sequential ecological study, based on state data, of US term deliveries that occurred during a 7-year period bounded by 2007 and 2013. The patterns of the timing of both term childbirth and term stillbirth were determined for each state and for the United States as a whole. Results A total of 46 usable datasets were obtained (45 states and the District of Columbia). During the 7-year period, there was a continuous reduction in all geographic entities in the proportion of term deliveries that occurred before 39 weeks of gestation. The overall rate of term stillbirth, when we compared 2007-2009 with 2011-2013, increased significantly (1.103/1000 vs 1.177/1000, RR 1.067, 95% confidence interval 1.038-1.096). Furthermore, during the 7-year period, the increase in the rate of US term stillbirth appeared to be continuous (estimated slope: 0.0186/1000/year, 95% confidence interval 0.002-0.035). Assuming 3.5 million term US births per year, and given 6 yearly "intervals" with this rate increase, it is possible that more than 335 additional term stillbirths occurred in the United States in 2013 as compared with 2007. In addition, during the 7-year period, there was a progressive shift in the timing of delivery from the 40th week to the 39th week. Absent this confounding factor, the magnitude of association between the adoption of the 39-week rule and the increase in rate of term stillbirth might have been greater. Conclusions Between 2007 and 2013 in the United States, the adoption of the 39-week rule caused a progressive reduction in the proportion of term births occurring before the 39th week of gestation. During the same interval the United States experienced a significant increase in its rate of term stillbirth. This study raises the possibility that the 39-week rule may be causing unintended harm. Additional studies of the actual impact of the adoption of the 39-week rule on major childbirth outcomes are urgently needed. Pressures to enforce the 39-week rule should be reconsidered pending the findings of such studies.

UR - http://www.scopus.com/inward/record.url?scp=84962603274&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84962603274&partnerID=8YFLogxK

U2 - 10.1016/j.ajog.2016.02.019

DO - 10.1016/j.ajog.2016.02.019

M3 - Article

C2 - 26880736

AN - SCOPUS:84962603274

VL - 214

SP - 621.e1-621.e9

JO - American Journal of Obstetrics and Gynecology

JF - American Journal of Obstetrics and Gynecology

SN - 0002-9378

IS - 5

ER -

Nicholson JM, Kellar LC, Ahmad S, Abid A, Woloski J, Hewamudalige N et al. US term stillbirth rates and the 39-week rule: A cause for concern? American journal of obstetrics and gynecology. 2016 May 1;214(5):621.e1-621.e9. https://doi.org/10.1016/j.ajog.2016.02.019