Assessment of weight changes during and after pregnancy: practical approaches

The usefulness of routine prenatal weight measurements in predicting pregnancy outcomes is still a controversial issue. Comparisons among studies and the interpretation of research findings are complicated due to the variety of indicators applied to express maternal weight changes during and after pregnancy. A review of literature was conducted to clarify the definitions and examine the strengths and limitations of methods for measuring gestational weight gain (WG) and postpartum weight changes. The reasons for weak correlations or non-significant associations between gestational WG and maternal and neonatal outcomes were probably owing to poor quality of obstetrics records and selection of wrong indicators to compute gestational WG. The choice of an indicator depends on clinical and research purpose, availability and reliability of data and cost. Considering the health implication of gestational WG, it is necessary to take into account the measurements used as initial and final weight, accuracy of gestational age estimation and the inclusion of fetal weight as part of maternal WG. Regardless of the indicators used to compute the weight changes after delivery, attention is drawn to the approach for designating prepregnancy weight, the time frame of postpartum weight measurements and the use of overlapping variables, which results in bias (part-whole correlation). It is necessary to address criticisms on the accuracy of prenatal weight measurements and the way of expressing the maternal weight changes during and after pregnancy in order to have reliable results from research.