ACTA REVIEW

Informed consent: providing information about prenatal examinations

KATJA DAHL1, ULRIK KESMODEL1,2, LONE HVIDMAN2 & FREDE OLESEN3

1Department of Epidemiology, Institute of Public Health, University of Aarhus, 8000 Aarhus C, Denmark, 2Department of

Obstetrics and Gynaecology, Aarhus University Hospital, Skejby Sygehus, 8200 Aarhus N, Denmark, and 3Intitute of Public

Health, Research Unit for the General Practice, University of Aarhus, 8000 Aarhus C, Denmark

AbstractBackground . Choice in prenatal care has moved on from a paternalistic approach, to increased patient autonomy andinformed decision-making. This review summarises the existing literature on the information of pregnant women aboutprenatal examinations. The extent to which information about Down syndrome and screening tests empowers informeddecision-making are investigated, as are different ways of expressing a risk estimate. Results . Knowledge scores can beimproved and decisional conflict reduced by group counselling, individual sessions, and by use of leaflets. None of theinterventions leads to a raise in anxiety scores or influence uptake rates. Satisfaction with information provided was foundunrelated to level of knowledge, but associated with having expectations for information met. Information on Downsyndrome is missing (13�21%), or restricted (13%), limitations of screenings tests rarely mentioned, and written materialsoften insufficient. Women experience risk expressed as proportions or relative risk ratio significantly higher than percentage,number needed to treat, or absolute risk reduction. More women correctly understand relative risk reduction compared toabsolute risk reduction and number needed to treat (60 versus 42 and 30%). Using medical words rather than lay termssignificantly alter risk perception. Conclusions . Information can increase the level of knowledge and reduce decisionalconflict, without raising anxiety scores. A clarification of the women’s expectations seems paramount to obtain a perceptionof good information and informed consent. The information provided about Down syndrome and screening tests does notempower an informed consent based on relevant knowledge.

Key words: Informed consent, prenatal care, providing information, risk expression, understanding risk

Abbreviations: ARR: absolute risk reduction, DS: Down syndrome, MeSH terms: medical subject headings, MSS:

maternal serum screening, NNT: number needed to treat, NTM: nuchal translucency measurement, -pLS: -point Likert scale,

RRR: relative risk reduction, STAI: State trait anxiety inventory

Introduction

Over the last two decades there has been a growing

consensus in the western world that health profes-

sionals have an obligation to provide pregnant

women with information to support an informed

consent to prenatal examinations. Information on

the limitations of the screening tests and potential

consequences of participation should be provided in

ways that respect patient autonomy and empowers

informed decision-making (1�4).

This review summarises the existing literature on

the information of pregnant women about prenatal

examinations. We evaluate ways of providing

information (individual and class sessions, leaflets,

decision-aided consultations and other more specific

interventions) with regard to attendance, anxiety,

knowledge, decisional conflict and patients’ satisfaction.

Information provided about Down syndrome and

screening tests are explored, as are different ways of

expressing a risk estimate.

Methods

The review is based on a systematic search strategy in

the electronic database Medline using 20 predefined

Correspondence: K. Dahl, Department of Epidemiology, Institute of Public Health, University of Aarhus, Vennelyst Boulevard 6 8000 Aarhus C, Denmark.

E-mail: kd@soci.au.dk

Acta Obstetricia et Gynecologica. 2006; 85: 1420�1425

(Received 10 April 2006; accepted 28 August 2006)

ISSN 0001-6349 print/ISSN 1600-0412 online # 2006 Taylor & Francis

DOI: 10.1080/00016340600985198

Medical Subject Headings (MeSH terms) in three

categories alone or in combination (Table I). Addi-

tional studies were identified from the reference lists

of individual papers obtained, and an additional

search in the electronic database Science Citation.

The purpose of each study was identified, and studies

potentially within the aim of this review selected. The

inclusion was, furthermore, only restricted by

method to quantitative studies with a randomised,

controlled, quasi-experimental, or cross-sectional

design.

The review includes 36 original studies from 12

different countries. All studies were assessed accord-

ing to number of participants, study period, study

design, confounder control, validation, item defini-

tions, and results.

Results

Interventions aimed at informing women about prenatal

examinations

Group counselling and individual sessions. The value of

offering women an extra information session, indi-

vidually or in class, are limited by the low attendance

(52% overall), lowest for the class session (42%) (5).

A test-re-test study (no control-group) showed a

modest but significant decrease in decisional conflict

after class session (O’Connor’s decisional conflict

scale: 16-item, 5-point Likert-scale [-pLS], mean

reduction�/0.22) without any change in anxiety

(State scale of the State-trait anxiety inventory

[STAI], controlling for trait anxiety scores). Knowl-

edge of maternal serum screening [MSS] was gen-

erally very low, and group counselling changed this

knowledge little (maximum increase 0.17 on 5-pLS

for those not previously informed). Knowledge of

nuchal translucency measurement [NTM] was gen-

erally greater and changed approximately 1 point on

5-pLS, independent of maternal education and

previous information (6). Improvement in knowl-

edge (both familiarity and more detailed knowledge)

is also observed after extra individual sessions, and a

significant decrease in mean anxiety scores later in

pregnancy described (Hospital Anxiety and Depres-

sion Scale: 6.1/21 for extra individual sessions

compared to 6.8/21 for routine and class sessions)

(5).

Leaflets. Leaflets are valued (49% tested and 43%

untested women) as the preferred type of information

of both screening and invasive diagnosis, only ex-

ceeded by face to face counselling with a doctor (70%

tested and 48% untested) (7). The majority read the

leaflets in full (60�86%) or flick through them (12%)

(8,9). Leaflets significantly improve knowledge

(8,10�13), decrease decisional conflict, raise satis-

faction with the amount of information received

(11,12,14), enhance perceived informed choice

(11�13), and significantly decrease anxiety (both

state and trait of the STAI) (8). However, an

evaluation of leaflets about NTM used in 14 UK

centres found that only 1 met the criteria for an

informed choice (15). An evaluation of 80�81

leaflets used in maternal serum DS screening found

many to be insufficient (16,17) (Table II).

Other interventions. An informational video about DS

seen by the pregnant woman before the hospital visit

was found to significantly improve knowledge of

screening (12 items covering the nature of DS, test

procedures, and the meaning of risk figures) and

enhance the retention of information more effec-

tively than written materials alone (p B/0.00007)

(18), without affecting uptake rates, specific worries

about abnormalities, or general anxiety significantly

(19).

Other interventions, such as a touch screen

computer information system in the waiting area,

audio taped recording of the consultations, or a

non-technical letter summarising the information

given during the consultation, were not influencing

Table I. MESH terms used in the systematic search strategy.

Information Prenatal examinations Pregnancy

Informed consent Prenatal care Pregnancy

Patient education Prenatal diagnosis Pregnant woman

Disclosure Ultransonography, prenatal Maternal-fetal relations

Mental competency Nuchal translucency measurement

Comprehension Down syndrome

Mental recall Enzyme tests

Information management Pregnancy-associated plasma Protein-A

Information dissemination Chorionic gonadotropin, beta subunit, human

Access to information

Prenatal examinations 1421

knowledge scores compared with information leaf-

lets or routine consultations with a computer gener-

ated ultrasound report. A significant reduction in

anxiety scores was observed for all three interven-

tions (STAI) (8,20).

Decision-aided consultations. Two, randomised, con-

trolled, trials among women with a positive MSS

result, found decisional conflict (O’Connor) to

decrease over time following decision-aided consul-

tations, compared to an increase following routine

consultations. More women in the decision-aided

group (25 versus 18%) perceived their screening

result as medium rather than high risk, with no

difference in actual MSS risk (p�/0.05). Decision-

aided consultations are found not to influence

up-take rates, anxiety scores (STAI) or knowledge

and are perceived as no more no less directive by

the counselees, but more time-consuming than

routine consultations (approximately 6 min longer)

(21,22).

Satisfaction with information

Mostly, both the written and the verbal informa-

tion are reported by the pregnant women, to be

good or fairly good, with figures ranging from 87

to 95% (8,23,24). Still, two French studies (re-

sponse rate 40%) showed that only 60% were

satisfied with the clarity and the quantity of the

information provided (verbal information), 43�47% stated the information to be of no help/

insufficient, 6% considered it non-existent. Infor-

mation on amniocentesis was considered insuffi-

cient by 39% of participants, and information on

DS children was deemed inadequate by 58%

(25,26). In one of the studies, all health profes-

sionals likely to be involved in prenatal care were

trained in genetic counselling (25).

Satisfaction with the information provided is not

associated with the achieved level of knowledge

(23�25,27) but associated with expectations. Pre-

counseling, the lowest level of satisfaction is seen

for women not expecting and not receiving any

information, but a significant improvement can be

achieved by providing this group with information

(28). Women offered an extra information session,

individually or in class, often feel more satisfied with

the information received, though satisfaction with

decision is unchanged (5).

The information provided about DS

Women with a screen positive result are not always

(13%) provided with information about DS (25).

Of the NTM-leaflets used in the 14 UK centres,

two described DS, and only as a mental handicap

(15), and of the 81 MSS leaflets, 21% where

without descriptive information about DS, and

13% mentioned DS only as a genetic or chromo-

somal abnormality (17). In the leaflets with de-

scriptive sentences of DS, 63% of the sentences

were classified as negative, 25% as neutral, and

only 12% as positive (17). With increased length

the message conveyed became more negative with

more medico-clinical details, but were also more

likely to contain some positive and neutral sen-

tences (17). Of the statements concerning DS, 89%

were of a medical, clinical, or epidemiological

nature. Only 11% referred to the social, educa-

tional, psychosocial or emotional aspects of persons

living with or parenting children with DS, and these

all came from only 16 leaflets. The inability to

predict severity before birth was mentioned in only

14% (16,17).

Insight into the nature of a screening test

The base line risk of having a baby with the

conditions being screened for is not part of the

information provided (29), and information on

sensitivity, specificity, or interpretation of tests

results are rare (15). At the beginning of their

pregnancy, most women (92%) have heard of

amniocentesis, but only 38% offered NTM and

69% offered MSS report being asked if they would

agree to have amniocentesis if the test result were

abnormal (13). Information prior to testing, as

well as information given during the ultrasound

scan, tends to focus on practical and technical

aspects of the test (when, where, and what the

tests screens for), whereas the possible conse-

quences and future perspectives are described

more vaguely (29,30).

Presenting a screening result

Subjective perception. Risk is understood in a personal

context with no significant correlation (r�/0.1)

Table II. Evaluation of 81 leaflets used in maternal Down

syndrome screening (32).

Misleading and/or inconsistent information 21%

Included all eight items recommended by the RCOG* 14%

Completely unacceptable 19%

�/80% of total possible scores 6%

Incorrect information 4%

Included all 17 items considered important by the authors 1%

*Royal Collage of Obstetricians and Gynaecologists.

1422 K. Dahl et al.

between actual risk for a given maternal age, and

perceived risk measured on an 8 point rating scale

(31). In a study on genetic counselees (men and

women), only about 15% of the counselees’ percep-

tion of own risk (measured on a 7-pLS), was

explained by the objective risks (recurrence risks

given by counsellors) (32). A priori perception of risk

was constituted of factors, such as prior knowledge

of recurrence risk (r�/0.38), self-health (r�/�/0.35),

parenthood concepts (r�/�/0.33), and experience

with the genetic disorder (r�/0.29) (32).

Presenting risk estimates. When presenting women

with a negative MSS result using a numerical

probability as opposed to a verbal expression,

slightly more women correctly answers the ques-

tion: what does this negative result mean (97 versus

91%, p�/0.04). Using numerical probabilities does

not affect anxiety (state form of STAI) (33).

Understanding and perception of a risk estimate is

influenced by the chosen numerical expression: for

both a desired and feared outcome proportions (1/

x) are experienced significantly higher than the

equivalent or even up to 2% larger percentage (x%)

(p B/0.0001) (34). Rates (x /1000 women per year)

are better reproduced than proportions with more

than 3 times as many women judging risks correctly

with rates (35). When communicating risk using

relative risk reduction [RRR] as opposed to abso-

lute risk reduction [ARR] and number needed to

treat [NNT] more correct answers are obtained: 60

versus 42 and 30%, respectively (p�/0.001) (36).

Studies document that both patients (37) and

doctors (38,39) find an estimate expressed as a

RRR bigger than the equivalent NNT and ARR,

that NNT are difficult for patients to use and

interpret, and that most patients (79% for RRR,

83% for ARR and 94% for NNT) are unable to

calculate the effect of an intervention in either

format (p�/0.004) (36).

Effects of framing. The choice of words used to

describe a condition or to inform someone about

the level of risk of an adverse event occurring,

significantly affect how the person perceives the

condition or risk (p B/0.0001). In total 74% found

‘trisomy’ and ‘translocation’ more worrying than ‘an

extra chromosome’ and ‘rearrangement’, 70% found

‘mutation’ more worrying than a ‘faulty gene’ (34).

Framing information on a risk estimate in a positive

direction makes the outcome sound significantly less

likely and less worrying (34,40).

Discussion

This review shows that raising knowledge can be

achieved without raising anxiety. Satisfaction is

related to having expectations met, and not level

of achieved knowledge. The content of information

provided does not empower an informed consent,

i.e. limitations of screening tests are rarely men-

tioned, and how to interpret a screening result is not

explained. Understanding and correct perception of

a risk estimate is better achieved with numerical

probabilities, with rates better reproduced than

proportions, RRR better understood and repro-

duced than NNT, and proportions experienced

higher than percentage. The choice of words can

significantly alter risk perception.

An intended objective evaluation, using both very

specific and more general search terms, has been

made of all included studies with no preliminary

hypothesis of associations influencing the evaluation.

Searching other databases and using other MeSH

words might reveal other relevant studies, but the

results of the included studies have been mostly

congruent with the few exceptions mentioned.

Issues of special concern with regard to prenatal

screening procedures, as well as any other screening

test, relate to test sensitivity, specificity, predictive

value as well as balanced information about the

conditions screened for. This review indicates that

the information provided only rarely include details

that will enable real informed choice. The prenatal

screening tests are mostly issued in an uncompli-

cated and positive manner, with the current infor-

mation practice being dominated by cost-efficiency

and the seeking of high uptake rates, rather than an

approach with detailed balanced information.

Further research is needed to understand reasons

for this, as well as the potential consequences of

informing women about the complexities and limita-

tions of screening tests. More research is needed on

the consequences of different information strategies

and the concept of informed consent: type, amount

and level of details when providing women with

information.

Acknowledgement

This review was made possible by a grant from the

Foundation of Clinical Development and Research

concerning the general practitioners and their inter-

face with other health care settings. (Forskningspul-

jen for den kliniske udvikling og forskning I almen

praksis og grænsefladerne til de øvrige sektorer I

sundhedsvæsnet.)

Prenatal examinations 1423

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