Discussion

The paper by de Onis et al. is a great achievement in obtaining for the first time global estimates of levels of IUGR in different countries and regions of the world. A problem that could introduce biases is that most of the data that are available from different parts of the world are from babies delivered at clinics, whereas in some regions, for instance in Africa, most babies are born at home, and it is not possible to judge the validity of extrapolations of prevalence and risk data from clinic to home deliveries. There is a need to determine whether data of hospital-born babies in developing countries are indeed representative of the larger proportion born at home.

Like Bakketeig, de Onis draws attention to the fact that while the focus of the workshop is primarily on IUGR infants born at term with a birthweight < 2500 g, there are also IUGR infants born prematurely and infants born with a birthweight ³ 2500 g who nevertheless were not able to attain their full growth potential and are therefore also to be considered IUGR. Figure 2 of the paper by de Onis et al. shows that perinatal mortality rates are highest among babies who are both premature and IUGR. In public health terms it is important to have data on newborns that are associated with the risk of one or more undesirable outcomes at a later stage in life. Birthweight, symmetry at birth, length of gestation, and the different etiologies underlying these parameters are all related to some extent, and at present it is not yet possible to say which of these factors or what combination (degree of IUGR being one of them) would permit to make the best prediction of preventable risk. In practical terms it is easiest to measure birthweight and to assess symmetry at birth using various anthropometric indicators. To get more valid estimates of length of gestation and degree of IUGR, a more frequent and universal use of ultrasonography dating would have to be advocated. Workshop participants agreed that this would not be making good use of scarce resources in developing countries and may even have unintended negative consequences in regions where female fetuses are more likely to be aborted than male ones. It was also emphasized that there is no evidence from randomized controlled trials that early diagnosis and delivery of IUGR babies with routine use of ultrasound has led to significantly improved outcomes in developed countries.

A WHO Expert Committee acknowledged and regretted the discontinuity in classification of growth retardation before and after delivery. The group dealing with fetal growth recommended that future growth curves be developed using the z-score system. It examined all available data sets on fetal growth using different criteria (an important one among these being associated risk data), to select the one of Williams in the US as the one with the fewest shortcomings. Williams' data were collected between 1972 and 1976, and Hoffman expressed the opinion that temporal trends may have rendered them obsolete in the US; nevertheless, WHO's Expert Committee has recommended them for international use as, on the basis of a number of criteria, they represent the best option presently available.

Some people still advocate the development of local growth curves. Several discussants reemphasized the evidence leading them to the conviction that all populations have the same growth potential (see discussion of Bakketeig paper), even though it may take more than one generation to attain it. The group's consensus is that, from a public health perspective (as opposed to case management), an international reference, based on the growth of healthy babies living under optimal conditions, should be used.

Appendix 1. Incidence of LBW and derived estimates of IUGR-LBW by country (1985-1995)

*Country*	*Data source*	*Year*	*LBW (% < 2500g)*	*IUGR-LBW¹ (%)*
Afghanistan	Monitoring system	1987	19.0	13.0
Albania	Registration data	1990	6.5	NA
Algeria	Field estimate	1988	9.0	4.4
Angola	Monitoring system	1987	21.4	15.0
Argentina	Registration data	1992	5.9	1.8
Australia	Western Pacific region data bank	1994	6.3	NA
Austria	Registration data	1985	5.8	NA
Bahamas	Monitoring system	1987	8.0	3.6
Bahrain	Registration data	1994	34.0	25.8
Bangladesh	Monitoring system	1987	50.0	39.4
Belarus	Monitoring system	1987	5.1	NA
Belgium	Registration data	1987	6.1	NA
Benin	Field estimate	1988	8.0	3.6
Bolivia	Field estimate	1988	12.0	7.0
Botswana	Field estimate	1988	8.0	3.6
Brazil	Registration data	1989	11.7	6.7
Brunei	Western Pacific region data bank	1994	5.0	1.0
Bulgaria	Monitoring system	1987	6.3	NA
Burkina Faso	Monitoring system	1987	10.8	6.0
Cambodia	Western Pacific region data bank	1994	18.4	12.4
Cameroon	Monitoring system	1987	10.0	5.3
Canada	Monitoring system	1987	5.6	NA
Central African Rep.	Monitoring system	1987	14.5	9.1
Chile	Registration data	1988	7.2	2.9
China	Western Pacific region data bank	1991	6.0	1.9
Colombia	Monitoring system	1987	17.3	11.5
Comoros	Monitoring system	1987	6.8	2.5
Costa Rica	Government report	1989	7.5	3.2
Cote d'Ivoire	Monitoring system	1987	15.0	9.6
Cuba	Registration data	1990	7.6	3.2
Cyprus	Monitoring system	1987	5.0	1.0
Czech Republic	Registration data	1994	5.5	NA
Denmark	Registration data	1991	5.4	NA
Djibouti	Monitoring system	1987	11.0	6.1
Dominica	Monitoring system	1985	10.5	5.7
Dominican Republic	Unknown source	1991	11.0	6.1
Ecuador	Field estimate	1988	11.0	6.1
El Salvador	Community-based data	1993	8.9	4.3
Eritrea	Unknown source	1993	13.0	7.8
Ethiopia	Hospital data	1988-93	8.9	4.3
Fiji	Western Pacific region data bank	1991	18.0	12.1
Finland	Registration data	1985	4.0	NA
Gabon	Monitoring system	1987	7.7	3.3
The Gambia	Unknown source	1989	24.0	17.2
Ghana	Monitoring system	1987	6.0	1.9
Greece	Registration data	1985	6.0	NA
Guatemala	Field estimate	1988	14.0	8.7
Guinea	Field estimate	1988	25.0	18.1
Guinea-Bissau	Hospital data	1987	20.4	14.1
Guyana	Monitoring system	1987	12.0	7.0
Haiti	Monitoring system	1987	15.0	9.6
Honduras	Field estimate	1988	20.0	13.8
Hungary	Government report	1993	9.9	NA
India	Estimate	1991	28.0	20.6
Indonesia	Monitoring system	1987	8.2	3.8
Iran	Government report	1991	8.0	3.6
Iraq	Hospital data	1991	8.0	3.6
Ireland	Registration data	1987	4.4	NA
Israel	Hospital data	1992	6.9	2.6
Jamaica	Monitoring system	1987	12.0	7.0
Japan	Western Pacific region data bank	1994	7.0	NA
Jordan	Monitoring system	1985	10.0	5.3
Lebanon	Monitoring system	1985	10.0	5.3
Lesotho	Monitoring system	1987	10.0	5.3
Libyan A.J.	Monitoring system	1987	5.0	1.0
Lithuania	Registration data	1992	4.4	NA
Luxembourg	Monitoring system	1987	6.2	NA
Madagascar	Estimate	1994	15.0	9.6
Malawi	Monitoring system	1987	10.0	5.3
Malaysia	Western Pacific region data bank	1994	8.3	3.8
Maldives	Government report	1993	20.0	13.8
Malta	Hospital data	1985	4.2	NA
Mauritania	Monitoring system	1985	10.0	5.3
Mauritius	Monitoring system	1987	7.7	3.3
Mexico	Field estimate	1988	12.0	7.0
Mongolia	Community-based data	1992	6.0	1.9
Morocco	Monitoring system	1985	9.0	4.4
Mozambique	Monitoring system	1987	11.3	6.4
Myanmar	Monitoring system	1987	15.9	10.3
Namibia	Hospital data	1990	11.9	6.9
New Zealand	Western Pacific region data bank	1994	5.7	NA
Nicaragua	Hospital data	1987	10.0	5.3
Niger	Monitoring system	1985	20.0	13.8
Nigeria	Field estimate	1988	20.0	13.8
Norway	Monitoring system	1985	4.5	NA
Oman	Hospital data	1992	9.0	4.4
Pakistan	Monitoring system	1987	25.0	18.1
Palau	Western Pacific region data bank	1994	9.6	4.9
Panama	Registration data	1985	9.8	5.1
Papua New Guinea	Western Pacific region data bank	1994	16.0	10.4
Paraguay	Monitoring system	1987	8.0	3.6
Peru	Field estimate	1988	9.0	4.4
Philippines	Western Pacific region data bank	1994	11.0	6.1
Poland	Registration data	1993	8.6	NA
Portugal	Registration data	1985	5.4	NA
Qatar	Monitoring system	1987	5.0	1.0
Rep. of Korea	Western Pacific region data bank	1988	4.3	0.4
Romania	Hospital data	1992	10.1	NA
Russian Federation	Monitoring system	1987	5.1	NA
Rwanda	Unknown source	1985	17.0	11.3
Saint Kitts and Nevis	Monitoring system	1985	9.4	4.8
Saint Lucia	Monitoring system	1985	9.7	5.0
Sao Tome and Principe	Monitoring system	1987	7.0	2.7
Saudi Arabia	Hospital data	1989	8.3	3.8
Senegal	Monitoring system	1985	10.0	5.3
Seychelles	Monitoring system	1987-88	10.1	5.4
Sierra Leone	Monitoring system	1987	13.0	7.8
Singapore	Western Pacific region data bank	1994	7.3	3.0
Slovenia	Government report	1992	6.0	NA
Solomon Islands	Western Pacific region data bank	1994	10.0	5.3
Sri Lanka	Community-based data	1993	18.7	12.7
Sudan	Estimate	1990	12.5	7.4
Suriname	Monitoring system	1987	13.0	7.8
Swaziland	Hospital data	1990	8.0	3.6
Sweden	Registration data	1985	4.2	NA
Switzerland	Registration data	1992-93	5.4	NA
Syrian Arab Republic	Unknown source	1990	11.0	6.1
Tajikistan	Registration data	1992	6.5	2.3
Thailand	Monitoring system	1987	7.7	3.3
Togo	Field estimate	1988	20.0	13.8
Trinidad and Tobago	Monitoring system	1987	13.0	7.8
Tunisia	Unknown source	1989	9.2	4.6
Turkey	Field estimate	1988	7.0	2.7
U. Rep. Tanzania	Community-based data	1992	16.9	11.2
U. Arab Emirates	Hospital data	1992	6.0	1.9
Ukraine	Monitoring system	1987	5.1	NA
United Kingdom	Monitoring system	1985	6.5	NA
United States	Registration data	1992	7.1	NA
Uruguay	Registration data	1992-93	7.6	3.2
Vanuatu	Western Pacific region data bank	1994	7.4	3.1
Venezuela	Monitoring system	1987	9.8	5.1
Viet Nam	Western Pacific region data bank	1994	10.8	6.0
Western Samoa	Western Pacific region data bank	1991	4.0	0.2
Yugoslavia	Monitoring system	1985	6.4	NA
Zaire	Government report	1990-93	25.0	18.1
Zimbabwe	Registration data	1989	5.6	1.5

¹ Derived using regression model Y= - 3.2452+0.852 X [see figure 1].
Data source: WHO Database on Low Birth Weight (update September 1996) (WHO, 1992).
NA = not applicable (developed country)

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