E. Rebecca Pschirrer, MD, MPH Dartmouth Medical School Maternal Fetal Medicine

OBESITY AND SCREENING FOR BIRTH DEFECTS

E. Rebecca Pschirrer, MD, MPH

Dartmouth Medical School

Maternal Fetal Medicine

Objectives

Review risks of obesity and congenital anomalies

Impact of BMI on screening

Review screening options

Best choices for obese patients

Background

2 – 3% live births affected by structural anomaly2.25% cardiac defect1 per 1500 neural tube defect

Majority of birth defects occur in euploid fetuses

Obesity Epidemic

2003-2004 National Health and Nutrition Examination Survey (NHANES)

Women 20 – 39 years old28.9 % BMI ≥ 30 kg/m2

8.0 % BMI ≥ 40 kg/m2

1999

Obesity Trends* Among U.S. AdultsBRFSS, 1990, 1999, 2008

(*BMI 30, or about 30 lbs. overweight for 5’4” person)

2008

1990

No Data <10% 10%–14% 15%–19% 20%–24% 25%–29% ≥30%

Data from CDC Behavior Risk Factor Surveillance System

Congenital Anomalies

Overweight & obesity associated with risk structural anomaliesNeural tube defects

Cardiovascular anomalies

Orofacial clefting

Other congenital anomalies

Watkins, Pediatrics, 2003 Population-based case-control study Pregestational diabetics excluded Spina bifida

OR 3.5, CI 1.2 – 10.3 Omphalocele

OR 3.3, CI 1.0 – 10.3 Cardiac defect

OR 2.0, CI 1.2 – 3.4 Multiple anomalies

OR 1.9, CI 1.1 – 3.4

Watkins, Pediatrics, 2003 Population-based case-control study Pregestational diabetics excluded Spina bifida

OR 3.5, CI 1.2 – 10.3 Omphalocele

OR 3.3, CI 1.0 – 10.3 Cardiac defect

OR 2.0, CI 1.2 – 3.4 Multiple anomalies

OR 1.9, CI 1.1 – 3.4

Stothard, JAMA, 2009

Systematic review & meta-analysis 1944 potential articles 39 review; 18 meta-analysis Pooled OR comparing risks among

overweight, obese, & recommended weight women

Anomalies ≥ 150 cases reported in literature

Stothard, JAMA, 2009 Spina bifida

OR 2.24, CI 1.86 – 2.69

CV anomalies OR 1.30, CI 1.12 – 1.51

Cleft palate OR 1.23, CI 1.03 – 1.47

Cleft lip and palate OR 1.20, CI 1.03 – 1.40

Anorectal atresia OR 1.48, CI 1.12 –

1.97

Hydrocephaly OR 1.68, CI 1.19 –

2.36

Limb reduction anomalies OR 1.34, CI 1.03 –

1.73


OR 2.24, CI 1.86 – 2.69





1.97


2.36


1.73


OR 2.24, CI 1.86 – 2.69





1.97


2.36


1.73

Stothard, JAMA, 2009

Congenital anomalies not analyzed in meta-analysis:Risk of omphalocele and risk of multiple

congenital anomalies significantly higher among obese women

Not included in meta-analysis due to low power / less than 150 cases reported

Malformation Etiology

Undiagnosed or unrecognized diabetes Altered metabolism ( insulin,

triglycerides, uric acid, estrogen)Increased insulin resistance Fuel mediated teratogenesis

Nutritional deficits Low folate levels

Supplementation not found to decrease risk

Challenges of Diagnosis

Poor sensitivity of ultrasound

“Ultrasound was limited by maternal habitus”

Spine & heart views particularly challenging in obese patients

Hendler, 2004, Intl Jnl Obesity


Dashe, J Ult Med, 2009


Retrospective cohort, singleton pregnancies, standard second trimester ultrasound exam (AIUM)

18 – 23+6 weeks EGA 10 components analyzed for adequacy

of visualizationCerebral ventricles, posterior fossa, midline

face, 4-chamber heart, spine, ventral wall, umbilical cord, stomach, kidneys, bladder



Exclusion criteria: indication for targeted ultrasoundPregestational DM, teratogen exposure, family

history, increased risk on screening 10,112 women 2676 (26%) obese Results: decrease in ability to adequately

visualize fetal anatomy with increasing maternal BMIClass 1 57%, class 2 41%, class 3 30%



Hendler, J Ult Med, 2005

SUV: Repeat the ultrasound?

Dashe, Obstet Gyn, 2009

Retrospective cohort, 5 year period 10,112 standard u/s 1,098 targeted u/s

79 fetuses with undiagnosed anomalies, 0.7%

Decreased detection of anomalies with increasing BMI with either standard or targeted ultrasound Detection even less in pregnancies complicated by

pregestational diabetes38% vs. 88%, p < 0.001

Challenges of Diagnosis:

Decreased Detection

Decreased detection of anomalies

Normal Overwt Class 1 Class 2 Class 3

66%

49% 48%42%

25%

97%91%

75%

88%

75%

Standard U/S Targeted U/S

Dashe, Ob Gyn, 2009

Dashe, Obstet Gyn, 2009

Broad range of anomalies not detectedStraight forward: endocardial cushion defectChallenging: micrognathiaNot detectable at 18 – 24 wks: GI atresiaNot detectable: absent ear canal

Residual risk after normal U/S:0.4% normal BMI1% BMI ≥ 30

Challenges of Diagnosis: Residual Risk

What to do?

Image enhancing modalitiesHarmonic imagingCompound imagingSpeckle reduction filters

Approach through least SQ adiposePeriumbilical, suprapubic, R / L iliac fossae

Endovaginal ultrasound

Techniques to Enhance Visualization

4-chamber heart Posterior fossa

First trimester anatomy?

11 – 13+6 weeks Endovaginal & abdominal u/s Structural malformation detection rates

range 16 – 84% Possible 2 stage process Not ready for prime time

Research re: feasibility, outcomesCost benefit analysis

Aneuploidy Screening Tests Maternal age Quad Screen First Trimester Screen Integrated Screen Sequential Screen Serum Integrated Screen

Weight Correction of Serum Analytes Adjust analyte concentration or MoMs

for maternal weight Placental- or fetal-derived markers more

diluted in heavier women due to larger blood volume

Conversely, more concentrated in lighter women because of smaller blood volume

Comparing Screening Methods for Down syndrome

Quad Marker Screen

First Trimester Screen

Serum Integrated

Screen

SequentialScreen

IntegratedScreen

Detection Rate 81% 84% 85% 89% 90%

Screen Positive 5% 5% 3% 3% 3%

Conclusions

Screening for birth defects & aneuploidy is a significant challenge in obese women

Reduction in detection rate of congenital anomalies

Discussion & documentation of limitations with patients

Document BMI in ultrasound reports

Thank you.

Documents

E. Rebecca Pschirrer, MD, MPH Dartmouth Medical School Maternal Fetal Medicine