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Does prenatal care improve birth outcomes: a critical review.
Fiscella K..
Does prenatal care improve birth outcomes: a critical review.
Obstetrics and Gynecology.,
1995,
85(3),
pp.468-479
Record status
This record is a structured abstract written by CRD reviewers. The original
has met a set of quality criteria. Since September 1996 abstracts have been
sent to authors for comment. Additional factual information is incorporated
into the record. Noted as [A:....].
Author's objective
To evaluate evidence that prenatal care improves birth outcomes. Type of
intervention
Prevention.
Specific interventions included in the review
Prenatal care including weekly and biweekly visits, home visitation by trained
lay workers, by black para-professionals, trained social workers, trained
midwives, a multidisciplinary team approach, cervical examinations, education
and the provision of "hot lines".
Participants included in the review
Pregnant women of several nationalities were studied including Latin American,
Australian, British and Americans. Adolescents and high risk women were
included.
Outcomes assessed in the review
The main outcomes were: percentage low birth weight, very low birth weight,
preterm delivery, small for gestational age and still birth, infant death and
neonatal mortality.
Study designs of evaluations included in the review
Studies that assessed the effect of prenatal care on birth outcomes were
included if they used statistical probability for birth outcomes based on some
measure of prenatal care. Time series were selected if groups were controlled;
cohort or case studies if an adjustment factor was used for prenatal visits
relative to gestational age. Non-randomised studies were selected if they
showed evidence that the treatment and control groups were comparable.
Randomised trials were excluded if there was evidence of contamination of
treatment and control groups.
What sources were searched to identify primary studies?
MEDLINE was searched from 1966 to October 1994. Relevant references cited in
retrieved articles also being included.
Criteria on which the validity (or quality) of studies was assessed
Studies were graded using the system developed by the United Sates
Preventative Services Task Force and assessed both for adequate statistical
power based on the specified outcome measure and using established criteria
for the evaluation of prenatal interventions.
How were the judgements of validity (or quality) made?
Not stated.
How were decisions on the relevence of primary studies made?
Not stated.
How was the data extracted from primary studies?
Risk ratios for adequate care were calculated.
Number of studies included
14 observational studies (669,876 women). 11 randomised controlled trials
(11,222 women). 12 time series. 13 quasi-experimental studies.
How were the studies combined?
Narrative review.
How were differences between studies investigated?
The potential causes of heterogeneity were discussed.
Results of the review
None of the randomised controlled trials of enhanced care showed positive
effects on rates of low birth weight infants or preterm delivery. There is
limited evidence from time series for cessation of effects. The strength of
association between prenatal care and outcome appears to be highly sensitive
to confounding.
Was any cost information reported?
A discussion on some of the issues surrounding costing of prenatal care was
included.
Author's conclusions
Current evidence does not satisfy the criteria necessary to establish that
prenatal care definitively improves birth outcomes. However, policy makers
must consider these findings in the context of prenatal care's overall
benefits and potential cost-effectiveness.
CRD commentary
This is a well written review which considers the problems of evaluating
research in the field in detail. Limiting the literature search to published
articles from MEDLINE may have resulted in failure to retrieve some relevant
studies. No information was given on either the time series or the
quasi-experimental studies and description of the prenatal care provided was
absent from particulars of the included observational studies. As the authors
discuss there are many problems with evaluating research in this area
including the lack of definition of adequate care, studies being controlled
for few of the many known confounding factors, unrecognised confounding
factors, any benefit of prenatal care being limited by the rate of modifiable
risk factors in the population and selection bias for participants in
observational studies. Included studies were graded for quality according to
predefined criteria. The evidence supporting causal criteria for the effect of
prenatal care on birth outcomes is considered and the findings that current
evidence does not satisfy these criteria supported.
Subject index terms
Subject indexing assigned by NLM: Pregnancy-Outcome; Prenatal-Care/ut
[utilization] Bias-Epidemiology; Confounding-Factors-Epidemiology; Pregnancy-;
Randomized-Controlled-Trials; Treatment-Outcome; United-States Female
Correspondence address
Dr. K Fiscella, Department of Family Medicine, University of Rochester School
of Medicine, 885 South Avenue, Rochester, NY 14620, USA.
Copyright
University of York, 1998
Database no.: DARE-951186
