Objective: To identify dietary factors related to the risk of gaining weight outside recommendations for pregnancy weight gain and birth outcome.
Design: An observational study with free-living conditions.
Subjects: Four hundred and ninety five healthy pregnant Icelandic women.
Methods: The dietary intake of the women was estimated with a semiquantitative food frequency questionnaire covering food intake together with lifestyle factors for the previous 3 months. Questionnaires were filled out at between 11 and 15 weeks and between 34 and 37 weeks gestation. Comparison of birth outcome between the three weight gain groups was made with ANOVA and Bonferroni post hoc tests. Dietary factors related to at least optimal and excessive weight gain during pregnancy were represented with logistic regression controlling for potential confounding.
Results: Of the women, 26% gained suboptimal and 34% excessive weight during pregnancy. Women in late pregnancy with at least optimal, compared with women with suboptimal, weight gain were eating more (OR = 3.32, confidence interval (CI)=1.81-6.09, P < 0.001) and drinking more milk (OR = 3.10, CI = 1.57-6.13, P = 0.001). The same dietary factors were related to excessive, compared with optimal, weight gain. Furthermore, eating more sweets early in pregnancy increased the risk of gaining excessive weight (OR=2.52, CI=1.10-5.77, P=0.029). Women with a body mass index of 25.0-29.9 kg/m(2) before pregnancy were most likely to gain excessive weight (OR = 7.37, CI 4.13-13.14, P < 0.001). Women gaining suboptimal weight gave birth to lighter children (P < 0.001) and had shorter gestation (P = 0.008) than women gaining optimal or excessive weight.
Conclusion: Women who are overweight before pregnancy should get special attention regarding lifestyle modifications affecting consequent weight gain during pregnancy. They are most likely to gain excessive weight and therefore most likely to suffer pregnancy and delivery complications and struggle with increasing overweight and obesity after giving birth.