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The 39 week rule: How did we get here and what have we

accomplished

James M Alexander MD

Objectives

• To understand the issues leading to the need for the 39 week rule.

• To identify strategies that help with implementation of the rule.

• To identify the impact of the rule on maternal and neonatal outcomes.

The natural length of gestation is 280 days from the first day of the Last Menstrual Period. Three things have occurred in obstetrics that have impacted and artificially decreased the average length of gestation to 273 days in our country.

- Accurate determination of gestational age

- Widespread use of ultrasound in routine practice

- Safe induction methods

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Determination of Gestational Age

• Historically based on LMP or known date of conception and

• Signs of pregnancy:– Positive

• Identification of fetal heart rate

• Perception of movement

• X-ray

– Probable• Anatomic changes

– Presumptive• Cessation of menses

• Changes in breasts

• Symptoms: N/V, urinary frequency, fatigue

Determination of Gestational Age

• Naegle’s rule

– Count back 3 months, then add 7 days

– Fairly accurate in determining the 280th day after the first day of the LMP

Advent of Ultrasound

• New precision in dating the pregnancy

• Universal implementation versus selective debate– RADIUS trial encouraged selective use

– ACOG has always stated that physicians are not obligated to perform sonography in low risk women

• Despite evidence that routine ultrasound in low risk women is unnecessary, it became standard of care.

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NICHD ultrasound workshop

• Recommends an ultrasound for fetal anatomy at 18 to 20 weeks for all women.

• If the dates are unsure, recommends a first trimester ultrasound.

• All women should be offered first trimester screening for aneuploidy.

• Otherwise ultrasound in pregnancy should have a specific indication.

Induction techniques

Over the years improvement in existing techniques and development of new ones have made inductions easier.

• Oxytocin Initially administered as a bolus given intranasally.

Intravenous and especially intravenous pumps came later.

Prostaglandin E1/ Misoprostol

Prostaglandin E2/ Prepidil, Cervidil

Cervical ripening techniques Laminaria

Foley bulb

Improved Nursery Outcomes

• Viability year gestational age

1900 30 – 32 weeks

1970 27 – 28 weeks

1990 25 – 26 weeks

2014 23 – 24 weeks

• Huge focus of research at the extremes of prematurity, not as much in the late preterm or near term gestation.

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Increase in prematurity is driven by late preterm births

Gestational age distribution of singleton preterm births, United States 2002.

Davidoff et. al, Semin in Perinatology, 2006

Shifting distribution of gestationalage among spontaneous singleton live births,

United States 1992, 1997, and 2002

Davidoff et. al, Semin in Perinatology, 2006

Preterm delivery rate

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Definitions and Terminologies

• Preterm: Birth prior to the end of the 36th week (259th day)

• Late Preterm: Birth between 34 0/7 weeks and 36 6/7 weeks (239th and 259th day)

• Early Term: Birth between 37 0/7th weeks and 38 6/7 weeks (260th to 273rd day)

Gestational age should be rounded down

Evidence for adverse outcomes in the Late preterm/Early term gestation

Respiratory Morbidity of the Late Preterm Infant

Hibbard et al. JAMA, 2010

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Respiratory Morbidity of the Late Preterm Infant

Hibbard et al. JAMA, 2010

Incidence of Adverse Neonatal Outcomes According to Completed Week of Gestation at Delivery.

Tita AT et al. N Engl J Med 2009;360:111-120.

Odds Ratios for Adverse Neonatal Outcomes According to Completed Week of Gestation at

Delivery.

Tita AT et al. N Engl J Med 2009;360:111-120.

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Cerebral Palsy among Term and Postterm Births

CP is 2.3x higher at 37wks and 1.5x higher at 38 wks than at 39-41 wks

Norwegian birth cohort of 1,682,441 singleton term births without congenital anomalies followed for a minimum of 4 years (maximum of 20 years) with identified CP in the National Health Insurance Registry.

Moster et al. JAMA 2010;304:976-982

Delivery indications at late preterm gestations and infant mortality rates

Reddy et. al, Pediatrics, 2014

Delivery indications at late preterm gestations and infant mortality rates

Reddy et. al, Pediatrics, 2014

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Delivery indications at late preterm gestations and infant mortality rates

Reddy et. al, Pediatrics, 2014

Based on the increased morbidity and mortality seen in the early term gestation new guidelines have been issued.

ACOG committee opinion 5612013

• Nonmedical indicated early term delivery is not appropriate.

• Acknowledges that certain medical conditions justify delivery in the late preterm or early term period.

• Recognizes that state Medicaid agencies will begin to decrease or stop reimbursement for non-indicated deliveries.

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Examples of Medical Indications for Late Preterm or Early Term Deliveries

• Hypertension• Oligohydramnios• Prior classical/myomectomy• Placenta previa/accreta• Twins• IUGR• Diabetes• Abruption• Chorioamnionitis• PROM• Cholestasis• Alloimmunization• Fetal anomalies

Non-Medical Reasons for Inductions <39 weeks

• Maternal intolerance to late pregnancy

– Excess edema, backache, indigestion, insomnia

• Prior labor complication

• Prior shoulder dystocia

• Suspected fetal macrosomia

• History of rapid labor/ lives far away

• Possible lower risk for mom or baby

– Lower stillbirth rate, less macrosomia, less preeclampsia

JCAHO performance measure

• Measures elective delivery rate.

• Improvement noted as a decrease in the rate.

• Includes:– ICD-9 codes for medical induction of labor as well as elective cesarean

deliveries between 37 and 38 completed weeks.

– Excludes patients in a defined list.

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Montana Public HealthPrevention Opportunities under the big sky

Feb 2014

• 12,000 births in the state each year.

• 27% or 3240 deliver between 36 to 38 weeks and 47% were delivered by induction or cesarean delivery.

• Although a bit of an estimate, 6 to 12 % of deliveries should be medically indicated.

• 2000 deliveries in the state may be due to non-medically indicated interventions.

Montana Public HealthPrevention Opportunities under the big sky

Feb 2014

How do we accomplish a decrease in the elective delivery rate and have we been successful?

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Pomona Valley Medical Centercase study

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Tallahassee Memorial Hospitalcase study

Recent Declines in Induction of Labor by Gestational Age

Osterman and Martin, NCHS, 2014

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Recent Declines in Induction of Labor by Gestational Age

Osterman and Martin, NCHS, 2014

Has there been any pushback?

Is the 39 week rule the best for everybody?

Myers et al., J of Perinatology, 2014

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Is the 39 week rule the best for everybody?

Myers et al., J of Perinatology, 2014

Optimal timing for scheduled repeat cesarean in women with multiple priors

• Abstract presented at 2014 SMFM annual meeting suggests it may be in the 38th week

– Maternal and perinatal complications improved

• Women with 3 prior cesareans may be best served with delivery between 37 and 38 weeks.

Preterm delivery rate