A WHO collaborative study of maternal anthropometry and pregnancy outcomes

Objectives: To evaluate to what degree anthropometric measurements are useful and efficient in predicting maternal and fetal outcomes in different country settings and to develop appropriate reference curves for maternal weight gain. Methods: A meta-analysis of 25 data sets providing information on over 111000 births worldwide. Results: Attained weight indicators from pre-pregnancy (Pp) through 9 lunar months demonstrated high odds ratios (O.R.) for both low birth weight (LBW) and intra-uterine growth retardation (IUGR). The strongest effect size (O.R. = 4.0) was provided by attained weight at 7 lunar months for IUGR, when applied to women of below average pre-pregnancy weight. The study indicators showed only minor and inconsistent O.R. for preterm birth (PTB). The ability of study indicators to predict the three maternal outcomes was much weaker. Maternal height as a predictor of assisted delivery showed the highest positive O.R. (1.6), but did not meet the screening criteria. Conclusions: A single measurement of attained weight at 5 or 7 lunar months (16–20 or 24–28 weeks) is the most practical screening instrument for LBW and IUGR in most primary health care settings and provides warning of the need for intervention. The operational value of these findings should be demonstrated through their successful large-scale application in service settings.