preterm prediction and prevention--hernandez
TRANSCRIPT
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
1/39
Preterm Labor
Prediction, Prevention,and Management
Jennifer Hernandez, M.D.
Maternal-Fetal Medicine
Obstetrix Medical Group of Texas
Fort Worth, Texas
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
2/39
Objectives
To review the background and epidemiology ofpreterm birth
To discuss risk factors and screening methods
available for predicting women at risk and toreview preventative options for those women atrisk
To review how to diagnose preterm labor andtreatment options available for those women
To discuss preterm labor in multi-fetal gestationsand how these differ from singleton pregnancies
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
3/39
Overview
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
4/39
Preterm Birth: Background
Preterm birth is defined as delivery prior to 37completed weeks gestation
Early preterm birth is defined as delivery priorto 34 weeks gestation
Late preterm birth is defined as deliverybetween 34 0/7- 36 6/7 weeks gestation
Preterm birth can be due to PTL (40-45%),PPROM (20-255%), or medically indicateddeliveries (30-35%)
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
5/39
Preterm Birth: Epidemiology
The incidence ofpreterm birthincreased more than
20% from 1990 to2006
This was largely due
to a rise in multiplegestations andmedically indicatedlate preterm deliveries
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
6/39
Preterm Birth: Epidemiology
Fortunately, the overall rate of preterm birth in theUnited States is decreasing, down to 11.7 percent in2011
This rate of preterm birth still remains higher thanother industrialized countries
The U.S. ranks 131st out 184 countries with reportedrates of preterm birth
Its not just a disparity between countries Vermont, New Hampshire, Oregon, and Maine all
have preterm birth rates < 9.6%
Louisiana, Mississippi, and Alabama all have rates
>14.6%
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
7/39
Preterm Birth: Significance
Why does it matter?
Preterm birth is the leading cause of neonatal
morbidity and mortality Long-term sequelae include neurodevelopmental
deficits and increased risk of chronic disease inadulthood
Preterm birth costs the health care system$26 billion annually
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
8/39
Preterm Birth: Significance
The risk of morbidityand mortalitydecrease as
gestational ageincreases, but therelationship is non-linear
The point with thelowest risk is between39 0/7 and 40 6/7weeks
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
9/39
Prediction
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
10/39
Preterm Birth: Risk Factors
Prior preterm birth The number one risk factor for preterm birth
The more preterm births, the stronger the risk of
recurrence:
One prior preterm birth: 14-22%
Two prior preterm births: 28-42%
More than 3 prior preterm births: 67% Most recurrent preterm births occur within 2
weeks of the gestational age of the prior pretermbirth
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
11/39
Preterm Birth: Risk Factors
Cervical and Uterine Factors
Short cervix There is an inverse relationship between cervical length by
ultrasound and gestational age at delivery More to come on this later.
Cervical surgery Ablative and excisional procedures for treatment of cervical
intraepithelial neoplasia have been associate with increasedrisk of preterm birth
Uterine malformations Congenital and acquired malformations are associated with
preterm birth
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
12/39
Preterm Birth: Risk Factors
Lifestyle factors
Smoking, Substance abuse
Body mass index
Physical activity, work, and stress
Demographic factors
Race
African Americans are at the highest risk for pretermbirth
Socioeconomic status
Educational status
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
13/39
Preterm Birth: Risk Factors
Infection Bacterial vaginosis and other vaginal infections
Asymptomatic bacteruria
Peridontal disease
Multiple gestation
Birth defects
Threatened abortion
Inter-pregnancy interval
Genetic factors
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
14/39
Preterm Birth: Screening
Transvaginal cervicalultrasonography An increased risk of PTB as
cervical length shortens has
been observed in allpopulations
Cervical length below the10th percentile (25 mm) isconsistently associated with
an increased risk of PTB 90th percentile: 45 mm
50th percentile: 35 mm
10th percentile: 25 mm
5th percentile: 20 mm
2nd percentile: 15 mm
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
15/39
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
16/39
Preterm Birth: Screening
Cervical length screening by history High risk population: Prior preterm birth < 34
weeks
Transvaginal ultrasound for cervical length every 2weeks from 16 to 24 weeks
Low risk population: No history of preterm birth One time transabdominal screening at anatomy
ultrasound (usually ~18 weeks) with transvaginalultrasound only if first measurement concerning
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
17/39
Preterm Birth: Screening
Fetal Fibronectin
A basement membrane protein produced by the fetalmembranes
Thought to act as an adhesion molecule that binds theplacenta and membranes to the uterine decidua
Rarely found in the vagina after 20 weeks gestation in anormal pregnancy
When found in the vagina after 20 weeks, it has been
associated with an increased risk of spontaneous PTB
Low sensitivity, high specificity
ACOG no longer recommends its use as a screening tool
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
18/39
Preterm Birth: Screening
Home uterine activity monitoring
Not recommended
Bacterial vaginosis screening
Not recommended
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
19/39
Prevention
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
20/39
Preterm Birth: Prevention
History
17-hydroxyprogesterone caproate injections
Any woman with a singleton gestation and prior
spontaneous preterm delivery should receive weeklyprogesterone injections from 16 to 36 weeks
Use of progesterone in these high risk patients hasbeen shown to significantly reduce the risk of recurrent
preterm birth This is thought to reduce inflammation, maintain
cervical integrity, and antagonize oxytocin
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
21/39
Preterm Birth: Prevention
Cervical length
High risk patients
Cerclage
If cervical length < 25 mm prior to 24 weeks Associated with a 30% reduction in preterm birth along with
decreased perinatal morbidity and mortality
Low risk patients
Vaginal progesterone If cervical length is < 20 mm prior to 24 weeks
Associated with ~ 45% reduction in preterm birth
Cerclage Has not been shown to significantly reduce preterm birth
rate, even at cervical lengths < 15 mm
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
22/39
Management
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
23/39
Preterm Birth: Symptoms
Cramping
Contractions
Low back pain Lower abdominal pressure
Vaginal discharge
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
24/39
Preterm Birth: Diagnosis
Its not preterm labor without cervical change
Contractions alone without cervical changecarry a 40-70% false-positive rate
Fetal fibronectin
The value is in its negative predictive value
>99% for delivery within 14 days
Positive predictive value Only 13-33% (!) for delivery in 7-10 days
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
25/39
Preterm Birth: Intervention
Tocolytics The goal of tocolysis is for short-term prolongation of
pregnancy to allow administration of antenatal
steroids a well as maternal transport if needed No evidence exists that tocolytic therapy has any
direct favorable effect on neonatal outcomes
Long-term use of any of these agents carries a high
risk for side effects both maternal and fetal A few examples: Magnesium sulfate, Calcium channel
blockers (Nifedipine), NSAIDs (Indomethacin), Beta-adrenergic receptor antagonists (Terbutaline)
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
26/39
Preterm Birth: Intervention
Antenatal corticosteroids This is the single most beneficial intervention for
improved neonatal outcomes in patients who deliver
preterm Neonates whose mothers receive steroids have
significantly lower severity and frequency ofrespiratory distress syndrome, intracranialhemorrhage, necrotizing enterocolitis, and death(compared to those who do not receive steroids)
Betamethasone and Dexamethasone are the mostwidely studied corticosteroids and are equivalent inefficacy
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
27/39
Preterm Birth: Intervention
Antenatal corticosteroids A single course of steroids is recommended for any
woman at risk for preterm delivery between 24 and 34
weeks A single rescue course at least 2 weeks after the first
course has additional neonatal benefit
However, regularly scheduled repeat courses are not
recommended
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
28/39
Preterm Birth: Intervention
Antibiotics
It has been theorized that infection orinflammation are associated with contractions
However, it has never been shown that antibiotictreatment in women with preterm labor and intactmembranes have any benefit in prolonging thepregnancy
This is different than the important antibioticprophylaxis for GBS prophylaxis and in the settingof rupture of membranes
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
29/39
Preterm Birth: Intervention
Neuroprotection
Pre-delivery administration of magnesium sulfatereduces the occurrence of cerebral palsy
Magnesium sulfate should be given with the intentfor neuroprotection when birth is anticipated priorto 32 weeks
Same protocol essentially as magnesium fortocolysis and preeclampsia seizure prophylaxis
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
30/39
Multiples
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
31/39
Preterm Birth: Multiples
In 2006, 60% of twins and 93% of triplets wereborn preterm
Unfortunately, many of the strategies listed
previously are ineffective or actually detrimentalin a multi-fetal pregnancy
Progesterone treatment does not reduce theincidence of preterm birth
Cerclage may actually increase the risk of pretermbirth not recommended
Tocolytics carry a much higher risk of side effects inthis population
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
32/39
Preterm Birth: Multiples
There is not even adequate data todemonstrate benefit from the use of antenatalsteroids in multiple gestations
However, because of the clear benefitattributable to corticosteroids in singletongestations, steroids are readily utilized in
multiple gestations The same concept applies to magnesium
sulfate for neuroprotection
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
33/39
Conclusions
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
34/39
Preterm Birth: Conclusions
Preterm birth remains a commoncomplication for many women in the UnitedStates
It carries a huge financial burden for familiesaffected as well as the health care system asa whole
There are multiple risk factors for pretermbirth, but a prior history of this event is thestrongest predictor of recurrence
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
35/39
Preterm Birth: Conclusions
There are few reliable methods of predictionavailable maternal history and cervicallength
There are even fewer reliable methods ofprevention once an increased risk of pretermdelivery is identified progesterone and
cerclage Preterm labor can be elusive at times
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
36/39
Preterm Birth: Conclusions
Once preterm labor is diagnosed, severaltreatments are available to reduce theneonatal morbidity and mortality if preterm
birth occurs antenatal steroids andmagnesium sulfate
Multifetal gestations have a very high risk of
preterm birth, but unfortunately, effectiveprevention and management options arelimited in this setting
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
37/39
Questions?
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
38/39
Thank you!
-
7/30/2019 Preterm Prediction and Prevention--Hernandez
39/39
References
Prediction and prevention of preterm birth. ACOG Practice Bulletin Number 130, October2012.
Cunningham FG, Leveno KJ, Bloom SL, et al. Williams Obstetrics. 23rd edition. McGrawHill. 2010.
Goldenberg RL, Mercer BM, Meis PJ., et al. The preterm prevention study: fetal fibronectintesting and spontaneous preterm birth. Obstet Gynecol. 1996;87:643-48.
Goldenberg RL, Iams JD, Das A., et al. The preterm prevention study: sequential cervical
length and fetal fibronectin testing for the prediction of spontaneous preterm birth. Am JObstet Gynecol 2000;182:636-43. Iams JD, Geldenberg RL, Meis PJ, et al. The length of the cervix and the risk of
spontaneous premature delivery. NEJM 1996;334:567-72. Lockwood CJ, Senyei AE, Dische MR, et al. Fetal fibronectin in cervical and vaginal
secretions as a predictor of preterm delivery. NEJM 1991;325:669-74. To MS, Alfirevic Z, Heath VC, et al. Cervical cerclage for prevention of preterm delivery in
women with short cervix: a randomised controlled trial. Lancet 2004;363:1849-53.
Goya M, Pratcorona L, Merced c, et al. Cervical pessary in pregnant women with a shortcervix (PECEP): an open label randomised controlled trial. Lancet 2012;379:1800-6.
Rouse DJ, Caritis SN, Peaceman aM, et al. A trial of 17 alpha-hydroxyprogesteronecaproate to prevent prematurity in twins. NEJM 2007:357:454-61.