Environmental Exposures and Low Birth Weight:

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Environmental Exposures and Low Birth Weight

• Association with Placental Arsenic Levels.

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B Duthie and Z-Q Lin, Southern Illinois
University, Edwardsville IL. S Richards, CD
Adair and L Mason, University of Tennessee,
Chattanooga TN. D Misra, University of Michigan,
Ann Arbor MI

• R.K. MILLER, PEDECS, University of Rochester,
  Rochester, NY

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Background

• Mothers who live in high As areas are at
  increased risk for giving birth to a low birth
  weight (LBW) infant. However, no biomarkers of
  exposure in mother or baby have been associated
  with LBW to date.

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Hypothesis

• High levels of As in pregnant women are
  associated with LBW.

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LBW in Hamilton County, TN
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Methods The patient sample

• Pregnant women were consecutively recruited at
  the time of delivery from the regional tertiary
  Obstetrics Center, Erlanger Hospital.
• Clinical charts were reviewed, the babies
  evaluated and their weights retrieved.
• Observed/expected (O/E) BW ratios were calculated
  from US mean BW adjusted for GA, race, parity and
  infant gender.

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Placental comparison sample

• UNC PIN3 sample of 1200 consecutive recruited
  mothers.
• Placentas weighed trimmed of cord and membranes.
• Fetoplacental weight ratio (FPR)
• Calculated as Birth weight
  Placental weight

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Methods The placentas

• Placentas were weighed trimmed of cord and
  membranes.
• Placental tissue As was determined by atomic
  absorption spectroscopy (detection limit 15
  ug/kg).
• The mean placental As was 39 mg/kg (lt15-824
  mg/kg).

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Descriptives
As
No As

• Birthweight lt2500 g 11.5 19 (65)
• Preterm birth (lt37 weeks) 18 24.2 (34)
• Caucasian race 60.6 66.6
• Tobacco use gt1/2 ppd 5 7.8
• Primiparas 36.1 27.1
• Week began prenatal care 11.6 wks 11.4 wks
• Height (in.) 64.2 in 63.6 in.
• Weight (lbs) 154 lbs 155 lbs
• Hematocrit 36.8 37.9
• Chronic hypertension 8.2 8.7
• Diabetes mellitus 3.3 4.7
• Asthma 23.0 7.5
• Preeclampsia 12.1 7.9
• Use of illicit substances 15.2 24.0
• Female gender 33.3 48.4
• Apgar lt7 at 5 minutes 3.0 3.2

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As distribution
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Results Placental As and BW
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Results Placental As and BW

• In As-exposed placentas, As and total placental
  As influence the O/E BW ratio.
• As (-).
• Total placental As ().

• We interpret this as placental growth
  compensating for negative effects of As on fetal
  growth.

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Results As and FPR

• North Carolina cohort (N632)
• 7.41.3,
• Our cohort
• 6.81.2, (plt0.0001).
• At a PW of 500 g, CHA babes are 300 g lighter
  than NC babes.

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More BW/PW

• The relationship between BW and PW is attenuated
  in CHA.

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BW and PW, why bother?

• Our population, despite its overall 17 rate of
  LBW, has statistically larger placentas.
• This observation could reflect effects of other
  toxicants.
• It is consistent with As-mediated relative
  placental dysfunction.

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As and chorionic plate growth
Total disk area
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As and chorionic plate growth
Chorionic vascular area
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As and chorionic plate growth
Area ratio Proportion of plate Covered by vessels
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As and chorionic plate growth
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As As h area ratioe1
Area ratio Proportion of plate Covered by vessels
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Area and perimeter

• Area pr2
• Perimeter2pr
• Area/Perimeter ratio

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As As h the area and perimeter radii converge
Area perimeter ratio compares radii
As placentas tend to be rounder.
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Limitation

• Weve only measured As.

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Conclusions

• We find an inverse association between placental
  As and O/E BW ratio.
• As-associated LBW may be mediated or marked by
  effects on placental growth.
• (NIMH K23 MH 067857-01)