Limitations of BMI in Pregnancy

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Limitations of BMI in Pregnancy

• Using BMI, in pregnancy in not accurate.
• It should be done pre and post pregnancy.
• BMI does not really convey differences in shape
  that are relevant to obstetric anaesthetists and
  for the surgery during normal pregnancy and
  instrumental delivery or C/S.

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The Scale of the Problem

• WHO Obesity is a worldwide epidemic.
• 250 Million obese people, 7 of world population.
  
• USA 65 of adults are obese or overweight.
  NHANES.
• UK Fastest growing obese population.
• 16 of obstetric patients gt100kg.
• 19.6 of women in the reproductive age are above
  BMI gt30.

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• Transition from Overweight to Obesity Worsens
  Pregnancy Outcome in a BMI-dependent Manner.
• Raatikainen K, Heiskanen N, Heinonen S. Obes
  Res. 2006 Jan14(1) 165-71.
• The risk of perinatal death more than doubles in
  the transition from an overweight to an obese
  condition.

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• Teratology public affairs committee position
  paper Maternal obesity and pregnancy.
• Scialli AR. Birth Defects Res A Clin Mol
  Teratol. 2006 Feb 76(2) 73-7.
• The literature suggests that women with a body
  mass index (BMI) gt/30 have approximately double
  the risk of having a child with a neural tube
  defect (NTD) compared to normal-weight women, and
  the increased risk associated with higher
  maternal body weight does not appear to be
  modified by folic acid supplementation.

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• The prevalence and impact of overweight and
  obesity in an Australian obstetric population.
• Callaway LK, Prins JB, Chang AM, McIntyre HD. E
  Floor, Clinical Sciences Building, Royal Brisbane
  and Womens Hospital, Herston QLD 4029,
  Australia. lcallaway_at_somc.uq.edu.au. Med J Aust.
  2006 Jan 16 184(2) 56-9.
• 11 of 252 women - ?BP, GDM, ?hospital admission,
  C/S, birth defect, preterm delivery, NICU
  admission.
• BMI should be routinely recorded on perinatal
  data collection sheets.

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• Recommendations for Weight Gain During Pregnancy

Description Recommended Total Weight Gain (lbs)
Underweight 28 40 (12-17 kgs.)
Normal weight 25 35 (11-15 kgs.)
Overweight 15-25 (6.5-11 kgs.)
Obese 15 (6.5 kgs.)

• Note multiple pregnancies.

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Recommendations for ALL women (including
preconception)

• Inform and counsel women about the health risks
  associated with overweight and obesity.
• Encourage a healthy diet
• Diets that restrict particular food groups are
  discouraged, especially during pregnancy.
• Screen for hypertension and diabetes mellitus in
  women who are at risk.
• Counsel women to consume adequate folic acid,
  iron and calcium.

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cont. Recommendations

• Encourage regular exercise (?30 minutes of
  moderate physical activity daily)
• Counsel women to quit smoking
• Counsel women to avoid consuming alcohol during
  pregnancy.
• Discuss recommended weight gain during pregnancy.

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After Pregnancy (postpartum)

• Recommendations for for ALL women PLUS the
  following
• Encourage breastfeeding.
• Counsel women to return to a healthy weight
• For women who are attempting to or have quit
  smoking, continue support to prevent postpartum
  relapse.

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Odds Ratios of Obesity and Overweight vs. Normal
Weight Status on Selected Pregnancy Outcomes
Missouri Singleton Pregnancies 1999-2003
Outcome Obesity vs. Normal Obesity vs. Normal Obesity vs. Normal
Outcome Odds Ratio 95 percent confidence interval 95 percent confidence interval
Very low birth weight (lt1500 grams) 1.23 1.15 1.32
Macrosomia (gt4499 grams) 2.52 2.36 2.69
Early preterm (lt32 weeks) 1.09 1.03 1.16
Congenital anomalies 1.17 1.09 1.25
Fetal death 1.30 1.17 1.45
Neonatal (lt28 days) death 1.31 1.15 1.51
Post-neonatal (1-11 months) death 1.17 0.97 1.42
Perinatal (fetal or neonatal death) 1.31 1.20 1.43
Infant (lt1 year) death 1.26 1.13 1.42
Fetal or infant death 1.29 1.19 1.39
Note Odds ratios calculated using multivariate
logistic regression with the following
covariates race, education, age, marital status,
smoking status of mother and birth order.
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• Infertility
• PCO
• Early pregnancy loss _________
• Insulin resistant
• Birth defects particularly neural tube defect

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• Labor delivery complications
• Preterm labour
• Prolonge 2nd stage
• Large babies ? shoulder dystocia instrumental
  delivery
• C/S ? C.P.D.
• Need for Oxytocin

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• Antenatal complications
• Maternal
• D.M.
• PET
• Hypertension

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Maternal complications

• Preterm Labour could be iotrogenic due to ?
  D.M., PET, HTN.
• Low birth weight
• - Women with relatively low pre-pregnancy
  weight more like to have PTL L.B.W.

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cont. Maternal complications

• Postpartum haemorrhage
• Wound infection
• Post C/S endometritis ? prolonged hospitalization
  
• Postpartum thromboembolic manifestation
  DVT, P.E.

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Fetal complications

• Neonatal death
• Birth defect neural tube defect
• Low Apgar Score
• More NICU admission

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• Cedergren MI (2004) A Swedish, population-based
  cohort study (n805,275)

Study Group Control Group Normal Weight
BMI gt 40
PET X 5 fold
Still Birth x 3 fold
LGA x 4 folds
Early NND x 3.5 fold
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• Baeten JM et al (2001) A population-based cohort
  study in Washington state based on birth data
  (n96,801).
• ? GDM
• PET
• Eclampsia
• C/S
• LGA infants