Topics in High Risk OB
Advanced maternal age, Twins, VBAC,
Preterm labor
Susan Wing Lipinski, M.D.
October 16, 2013
Learning Objectives
 To become familiar with non-invasive options for prenatal
testing and the appropriate indications for use
 To become familiar with different types of twin gestations and
the unique risks associated with each
 To understand the risk and benefits associated with a trial of
labor after Cesarean section
 To become familiar with preventative treatments for preterm
labor
Advanced Maternal Age
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Age 35 years or older at anticipated date of delivery
Increased risk of miscarriage
Increased risk of trisomies – 13, 18, 21 especially
Increased risk of gestational diabetes and preeclampsia
Increased risk of stillbirth
Number of women delaying childbirth is increasing
 1970 – 1 in 100 first pregnancies to mothers over age 35
yrs
 2006 – 1 in 12
Non-invasive prenatal
testing
Quad screen
Integrated screen
Cell-free DNA testing
Invasive Prenatal testing =
Amniocentesis
Quad screen
 Developed from AFP testing into triple marker screen and
now quadruple marker screening
 First option available to those under age 35 yrs – introduced
in 1984
 SCREENING test – not diagnostic
 Estimates risk of trisomy 13, 18,21; abdominal wall defects;
neural tube defects; indirect information about placenta and
risk of preeclampsia.
 Blood draw between 15-20 weeks
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Alpha-fetoprotein
hCG
Estriol
Inhibin -A
Integrated screen
 Takes the Quad screen (2nd trimester screening) and
combines with first trimester US of nuchal thickness and first
trimester biochemical markers
 Done at 11-13 weeks
 Detection rate for Down Syndrome 94-96%
 Biochemical markers tested
 Free B-hCG
 PAPP-A (pregnancy associated plasma protein A)
Cell-free DNA testing
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Newest option available
Only validated in high risk patient populations
Can be done as early as 10 weeks up until 32 weeks
Several tests available – Materniti21 most widely used in this
area
 Highly accurate at identifying the following:
 Trisomy 13, 18, 21
 Sex chromosome aneuploidies (XXY, X0, XYY, XXX)
 Identifying gender – important for families with X-lined diseases
Taken from Se
Taken from www.sequenom.com
Who gets Cell-free DNA test?
 Age over 35 years
 Personal or family history of
chromosomal abnormalities
 Fetal ultrasound suggestive of
aneuploidy
 Positive screening test
Prevention of stillbirth
 Unclear etiology
 Studies do not support placental insuffiency as
cause
 Studies do show benefits of NST testing
 OR of stillbirth compared to age 25-29 yrs
 35-39 yrs OR is 1.8 – 2.2
 40+ yrs OR is 1.8-3.3
 When to test?
 Start 36-38 weeks then test weekly till delivery
 Some benefit to twice weekly testing for those over age 40 yrs
 Some benefit to delivery at 39 weeks in those over 40 yrs.
Twins
Monozygotic vs. Dizygotic
 Dizygotic are always Dichorionic/Diamniotic
 Monozygotic can be any type of chorionicity/amnionicity
 Dichorionic/Diamniotic twins
 85% dizygotic
 15% monozygotic
Embryologic development
monozygotic twins
Morula
Days 1-3
Dichorionic/Diamniotic
Blastocyst
Days 4-8
Monochorionic/Diamniotic
Implanted
Blastocyst
Days 8-13
Formed
Embyonic disc
Days 13-15
Monochorionic/
Monoamniotic
Conjoined twins
US identification of twin
chorionicity
 Best determined in first trimester
 Absolutely necessary to know in order to determine
appropriate follow up!
 Twin peak sign -
“Heaping up” of villi into intermembrane space
Risks associated with all twin
gestations
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Preterm labor
Small birth weight and IUGR
Gestational diabetes
Preeclampsia, Acute fatty liver of pregnancy
DVT/PE
Cerebral palsy – 4 times that of a singleton pregnancy!
Increased risk of admission to NICU
Since 1980 there has been a 65% increase in twins and
500% increase in triplets and higher-order births!
Risks unique to Mono/Di Twins
 Twin-to-Twin transfusion syndrome (TTTS) – 10-15% of
Mono/di twins
 Twin anemia-polycythemia sequence (TAPS) – variant of
TTTS with normal amniotic fluid volumes
 Twin reversed arterial perfusion sequence (TRAP) –
acardiac twin uses co-twin for perfusion. 1% of mono/di
 Selective intrauterine growth restriction
 Early identification of all of these results in the best outcome
– this is the area where intrauterine surgery is taking off!
Twin-to-Twin Transfusion
Risks Unique to Mono/Mono twins
 1 in 10,000 pregnancies
 Twin-to-Twin transfusion is less common but
possible
 Cord entanglement
 Begins in first trimester
 Results in up to 23% mortality in utero
Monitoring of twin pregnancies
 All twin gestations need growth US every 4 weeks through
out pregnancy
 Monochorionic should have q2 week US from 16-28 to
screen for TTTS and its variants
 NST screening should be done in 3rd trimester on all twins
 Monochorionic/Monoamniotic twins should be referred to
tertiary care center for hospitalized monitoring in 3rd trimester
Trial of Labor after Cesarean
section – the VBAC controversy
Why all the fuss?
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30.8% of deliveries in Iowa were C/sections last year
<20% of women have a VBAC
Serious potential risks with BOTH Cesarean delivery and VBAC
ACOG practice bulletin in 2004 used the following wording
“immediate availability of Cesarean section.”
 This was interpreted to mean immediate surgical availability and
therefore, in-house surgeon and anesthesia
 As a result, many smaller hospitals discontinued VBAC’s and
required RLTCS
 Wording was revised in 2010 to try to promote more VBAC’s
What the evidence shows  Most maternal morbidity during a trial of labor occurs when
repeat LTCS becomes necessary
 Overall risks for maternal complications in repeat LTCS or
VBAC are very low
 For those with successful VBAC there are significant health
advantages
 Minimal difference in neonatal morbidity between elective
repeat LTCS and trial of labor
 Probability of successful VBAC is 60-80%
 Risks for VBAC after 2 Cesarean deliveries is only minimally
increased
What do we do with this info?
 Counsel patients about the true risks
 There are VERY few absolute contraindications
 Decisions should be on case-by-case basis
 Start the conversations about VBAC/RLTCS early in
pregnancy
 Support a patient’s right to choose her delivery route
 Respect for patient autonomy argues that even if a hospital
does not “offer VBAC” you cannot force a woman to have a
Cesarean delivery
Preterm labor
 Delivery between 20 0/7 weeks to 36 6/7 weeks
 In 2010 12% of infants were born before 37 completed
weeks
 Risks associated with preterm birth follow the child into early
childhood
 Greatest predictor is history of a prior preterm birth
Options for prevention
 Progesterone supplementation from 16-36 weeks
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Vaginal – Progesterone suppositories 100-200 mg nightly
IM injection – Makena and compounded 17 HP weekly
No proven benefit in twin gestation
Should be offered to EVERYONE with history of spontaneous
preterm birth
 Cerclage
 Controversial
 No proven benefit in twin gestation
Following up a history of Preterm
labor
 Start with counselling at first OB visit
 Look for preventable causes such as STD’s, UTI’s, smoking,
substance abuse, low body weight (BMI<19)
 Offer Progesterone therapy
 Ultrasound for cervical length q 2 weeks from 16-23 weeks
 If cervical length 25-29 mm then move to weekly US
 If cervical length <25 mm then refer for possible cerclage
placement
Bibliography
 ACOG Practice Bulletin #77 – Screening for Fetal Chromosomal
Abnormalities
 Reddy et. al. Maternal age and the risk of stillbirth throughout
pregnancy in the United States. Am J Obstet Gyn. 195: 764770. (2006)
 Bahtiyar et. al. Stillbirth at term in women of advanced
maternal age in the United States: when could the antenatal
testing be initiated? Am J. Perinatology. 25(5): 301-304. (2008)
 ACOG Practice Bulletin #56 – Multiple Gestation: Complicated
twin, triplet, and high-order multifetal pregnancy
 Uptodate – Monoamniotic twin pregnancy
 Uptodate – Twin pregnancy: Prenatal issues
 ACOG Practice Bulletin #115 – Vaginal birth after previous
Cesarean Delivery
 ACOG Practice Bulletin #130 – Prediction and Prevention of
Preterm birth