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  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 weeks  Alpha-fetoprotein  hCG  Estriol  Inhibin -A

Integrated screen  Takes the Quad screen (2 nd trimester screening) and combines with first trimester US of nuchal thickness and first trimester biochemical markers  Done at 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  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

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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 yrs  yrs OR is 1.8 – 2.2  40+ yrs OR is  When to test?  Start 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 Blastocyst Days 4-8 Implanted Blastocyst Days 8-13 Formed Embyonic disc Days Dichorionic/Diamniotic Monochorionic/Diamniotic 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  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 to screen for TTTS and its variants  NST screening should be done in 3 rd trimester on all twins  Monochorionic/Monoamniotic twins should be referred to tertiary care center for hospitalized monitoring in 3 rd trimester

Trial of Labor after Cesarean section – the VBAC controversy

Why all the fuss?  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 % 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 weeks  Vaginal – Progesterone suppositories 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 weeks  If cervical length 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: (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): (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