Too Much Intensive Prenatal Care

1
Too Much Intensive Prenatal Care?

• Pierre Buekens, MD, PhD
• The University of North Carolina at Chapel Hill

2
Kogan et al., 2000

• The intensification of prenatal care among twin
  pregnancies between 1981 and 1997 was associated
  with an increase of preterm births.
• Open questions
• Was the intensification of prenatal care the
  cause of the increase in preterm births?
• What are the potential mechanisms involved?
• What is the impact on mortality?

3
Causal Relationship?

• A randomized controlled trial comparing different
  levels of intensity of prenatal care would
  provide the best evidence of a causal
  relationship.
• No such randomized controlled trial has been
  performed among twin pregnancies.

4
Randomized Controlled Trials (All Pregnancies)

• A meta-analysis of 6 trials showed that a
  reduction in the number of prenatal visits did
  not change preterm birth rates (odds ratio (OR)
  0.93 95 confidence interval (CI) 0.86-1.02)
  (Villar Khan-Neelofur, 2001).
• There is thus no evidence suggesting a causal
  relationship between intensity of prenatal care
  and singleton preterm births.

5
Twins vs. Singletons

• The relationship between intensity of prenatal
  care and birth outcomes could be stronger among
  twins than among singletons.
• Twins are at
• Higher risk of poor birth outcomes
• Higher risk of interventions.

6
Twins vs. Singletons
CANADA
Joseph et al., 1998
7
Mechanisms?

• One of the mechanisms of the increase in twin
  preterm births between 1981 and 1997 was an
  increase of medically indicated preterm births.
• Other potential mechanisms
• Stress
• Side effects of preventive treatments (e.g., bed
  rest).

8
Bed Rest and Preterm Births

• A meta-analysis of randomized controlled trials
  of hospitalization for bed rest in women with an
  uncomplicated twin pregnancy showed that
  significantly more women gave birth very preterm
  ( 1.01-3.34) in the bed rest group than in the
  control group (Crowther, 2001) .

9
Bed Rest and Preterm Births
Hospitalization for bed rest in women with an
uncomplicated twin pregnancy
10
Mechanisms and Causal Relationship

• The relationship between intensity of prenatal
  care and twin preterm births could be partly
  explained by established mechanisms.
• Intensity of prenatal care might only be a marker
  of aggressive obstetrical management.

11
Impact on Infant Mortality

• Kogan et al., 2000
• Mortality was lower among intensive prenatal care
  users.
• The decrease in mortality did not differ by
  prenatal care utilization level.

12
Impact on Infant Mortality?
Per 1000 Live Births
Kogan et al., 2000
13
Impact on Infant Mortality

• Potential confounding by socio-demographic
  status
• Intensive users might be a selected group (e.g.,
  Assisted Reproductive Technology users).
• Potential mechanisms
• Early detection of fetal growth retardation and
  fetal distress (effectiveness not established)
• Access to tertiary care facilities with neonatal
  intensive care units.

14
Impact on Infant Mortality

• Would the infant mortality decrease have been
  greater if preterm births would not have
  increased?

15
Conclusions

• An increase in intensive prenatal care among twin
  pregnancies might not be beneficial and might
  increase preterm births.
• Health providers should be informed of the
  potential risks of the intensification of
  prenatal care.