Perinatal outcomes in low-risk term pregnancies: do they differ by week of gestation?

Yvonne W. Cheng, James Nicholson, Sanae Nakagawa, Tim A. Bruckner, A. Eugene Washington, Aaron B. Caughey

Research output: Contribution to journalArticle

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Abstract

Objective: The objective of the study was to examine whether the risk of perinatal complications increases with increasing gestational age among term pregnancies. Study Design: This is a retrospective cohort study of low-risk women with term, singleton births in 2003 in the United States. Gestational age was subgrouped into 37, 38, 39, 40, and 41 completed weeks. Statistical comparison was performed using χ2 test and multivariable logistic regression models, with 39 weeks' gestation as the referent. Results: There were 2,527,766 women meeting study criteria. Compared with 39 weeks, delivery at 37 or 38 weeks had lower risk of febrile morbidity but slightly higher risk of cesarean delivery. Delivery at 40 or 41 weeks was also associated with higher overall maternal morbidity. For neonates, delivery at 40 or 41 weeks had higher risk of birthweight greater than 4500 g, neonatal injury (40 weeks: adjusted odds ratio [aOR] 1.11 [95% confidence interval (CI), 1.05-1.18]; 41 weeks: aOR 1.27 [95% CI, 1.17-1.37]) and meconium aspiration (40 weeks: aOR 1.55 [95% CI, 1.43-1.69]; 41 weeks: aOR 2.12 [95% CI, 1.91-2.35]). Delivery at 37 or 38 weeks had higher risk of hyaline membrane disease (37 weeks: aOR 3.12 [95% CI, 2.90-3.38]); 38 weeks: aOR 1.30 [95% CI, 1.19-1.43]) but lower risk of meconium aspiration. Conclusion: The risk of cesarean delivery and neonatal morbidity in low-risk women increases at 40 weeks and beyond, whereas the odds of serious neonatal pulmonary disease were highest at 37 weeks. Recognition of such variation in term outcomes should lead providers to avoid iatrogenic morbidity and consider interventions to prevent complications of late-term pregnancy.

Original languageEnglish (US)
Pages (from-to)370.e1-370.e7
JournalAmerican journal of obstetrics and gynecology
Volume199
Issue number4
DOIs
StatePublished - Jan 1 2008

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Pregnancy
Odds Ratio
Confidence Intervals
Meconium Aspiration Syndrome
Morbidity
Gestational Age
Infant, Newborn, Diseases
Logistic Models
Term Birth
Hyaline Membrane Disease
Lung Diseases
Cohort Studies
Fever
Retrospective Studies
Mothers
Newborn Infant
Wounds and Injuries

All Science Journal Classification (ASJC) codes

  • Obstetrics and Gynecology

Cite this

Cheng, Y. W., Nicholson, J., Nakagawa, S., Bruckner, T. A., Washington, A. E., & Caughey, A. B. (2008). Perinatal outcomes in low-risk term pregnancies: do they differ by week of gestation? American journal of obstetrics and gynecology, 199(4), 370.e1-370.e7. https://doi.org/10.1016/j.ajog.2008.08.008
Cheng, Yvonne W. ; Nicholson, James ; Nakagawa, Sanae ; Bruckner, Tim A. ; Washington, A. Eugene ; Caughey, Aaron B. / Perinatal outcomes in low-risk term pregnancies : do they differ by week of gestation?. In: American journal of obstetrics and gynecology. 2008 ; Vol. 199, No. 4. pp. 370.e1-370.e7.
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abstract = "Objective: The objective of the study was to examine whether the risk of perinatal complications increases with increasing gestational age among term pregnancies. Study Design: This is a retrospective cohort study of low-risk women with term, singleton births in 2003 in the United States. Gestational age was subgrouped into 37, 38, 39, 40, and 41 completed weeks. Statistical comparison was performed using χ2 test and multivariable logistic regression models, with 39 weeks' gestation as the referent. Results: There were 2,527,766 women meeting study criteria. Compared with 39 weeks, delivery at 37 or 38 weeks had lower risk of febrile morbidity but slightly higher risk of cesarean delivery. Delivery at 40 or 41 weeks was also associated with higher overall maternal morbidity. For neonates, delivery at 40 or 41 weeks had higher risk of birthweight greater than 4500 g, neonatal injury (40 weeks: adjusted odds ratio [aOR] 1.11 [95{\%} confidence interval (CI), 1.05-1.18]; 41 weeks: aOR 1.27 [95{\%} CI, 1.17-1.37]) and meconium aspiration (40 weeks: aOR 1.55 [95{\%} CI, 1.43-1.69]; 41 weeks: aOR 2.12 [95{\%} CI, 1.91-2.35]). Delivery at 37 or 38 weeks had higher risk of hyaline membrane disease (37 weeks: aOR 3.12 [95{\%} CI, 2.90-3.38]); 38 weeks: aOR 1.30 [95{\%} CI, 1.19-1.43]) but lower risk of meconium aspiration. Conclusion: The risk of cesarean delivery and neonatal morbidity in low-risk women increases at 40 weeks and beyond, whereas the odds of serious neonatal pulmonary disease were highest at 37 weeks. Recognition of such variation in term outcomes should lead providers to avoid iatrogenic morbidity and consider interventions to prevent complications of late-term pregnancy.",
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Cheng, YW, Nicholson, J, Nakagawa, S, Bruckner, TA, Washington, AE & Caughey, AB 2008, 'Perinatal outcomes in low-risk term pregnancies: do they differ by week of gestation?', American journal of obstetrics and gynecology, vol. 199, no. 4, pp. 370.e1-370.e7. https://doi.org/10.1016/j.ajog.2008.08.008

Perinatal outcomes in low-risk term pregnancies : do they differ by week of gestation? / Cheng, Yvonne W.; Nicholson, James; Nakagawa, Sanae; Bruckner, Tim A.; Washington, A. Eugene; Caughey, Aaron B.

In: American journal of obstetrics and gynecology, Vol. 199, No. 4, 01.01.2008, p. 370.e1-370.e7.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Perinatal outcomes in low-risk term pregnancies

T2 - do they differ by week of gestation?

AU - Cheng, Yvonne W.

AU - Nicholson, James

AU - Nakagawa, Sanae

AU - Bruckner, Tim A.

AU - Washington, A. Eugene

AU - Caughey, Aaron B.

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N2 - Objective: The objective of the study was to examine whether the risk of perinatal complications increases with increasing gestational age among term pregnancies. Study Design: This is a retrospective cohort study of low-risk women with term, singleton births in 2003 in the United States. Gestational age was subgrouped into 37, 38, 39, 40, and 41 completed weeks. Statistical comparison was performed using χ2 test and multivariable logistic regression models, with 39 weeks' gestation as the referent. Results: There were 2,527,766 women meeting study criteria. Compared with 39 weeks, delivery at 37 or 38 weeks had lower risk of febrile morbidity but slightly higher risk of cesarean delivery. Delivery at 40 or 41 weeks was also associated with higher overall maternal morbidity. For neonates, delivery at 40 or 41 weeks had higher risk of birthweight greater than 4500 g, neonatal injury (40 weeks: adjusted odds ratio [aOR] 1.11 [95% confidence interval (CI), 1.05-1.18]; 41 weeks: aOR 1.27 [95% CI, 1.17-1.37]) and meconium aspiration (40 weeks: aOR 1.55 [95% CI, 1.43-1.69]; 41 weeks: aOR 2.12 [95% CI, 1.91-2.35]). Delivery at 37 or 38 weeks had higher risk of hyaline membrane disease (37 weeks: aOR 3.12 [95% CI, 2.90-3.38]); 38 weeks: aOR 1.30 [95% CI, 1.19-1.43]) but lower risk of meconium aspiration. Conclusion: The risk of cesarean delivery and neonatal morbidity in low-risk women increases at 40 weeks and beyond, whereas the odds of serious neonatal pulmonary disease were highest at 37 weeks. Recognition of such variation in term outcomes should lead providers to avoid iatrogenic morbidity and consider interventions to prevent complications of late-term pregnancy.

AB - Objective: The objective of the study was to examine whether the risk of perinatal complications increases with increasing gestational age among term pregnancies. Study Design: This is a retrospective cohort study of low-risk women with term, singleton births in 2003 in the United States. Gestational age was subgrouped into 37, 38, 39, 40, and 41 completed weeks. Statistical comparison was performed using χ2 test and multivariable logistic regression models, with 39 weeks' gestation as the referent. Results: There were 2,527,766 women meeting study criteria. Compared with 39 weeks, delivery at 37 or 38 weeks had lower risk of febrile morbidity but slightly higher risk of cesarean delivery. Delivery at 40 or 41 weeks was also associated with higher overall maternal morbidity. For neonates, delivery at 40 or 41 weeks had higher risk of birthweight greater than 4500 g, neonatal injury (40 weeks: adjusted odds ratio [aOR] 1.11 [95% confidence interval (CI), 1.05-1.18]; 41 weeks: aOR 1.27 [95% CI, 1.17-1.37]) and meconium aspiration (40 weeks: aOR 1.55 [95% CI, 1.43-1.69]; 41 weeks: aOR 2.12 [95% CI, 1.91-2.35]). Delivery at 37 or 38 weeks had higher risk of hyaline membrane disease (37 weeks: aOR 3.12 [95% CI, 2.90-3.38]); 38 weeks: aOR 1.30 [95% CI, 1.19-1.43]) but lower risk of meconium aspiration. Conclusion: The risk of cesarean delivery and neonatal morbidity in low-risk women increases at 40 weeks and beyond, whereas the odds of serious neonatal pulmonary disease were highest at 37 weeks. Recognition of such variation in term outcomes should lead providers to avoid iatrogenic morbidity and consider interventions to prevent complications of late-term pregnancy.

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