ORIGINAL ARTICLE Maternal diet in early and late pregnancy in relation to weight gain AS Olafsdottir 1,3 , GV Skuladottir 2 , I Thorsdottir 3 , A Hauksson 4 and L Steingrimsdottir 1 1 Public Health Institute of Iceland, Reykjavik, Iceland; 2 Department of Physiology, University of Iceland, Reykjavik, Iceland; 3 Unit for Nutrition Research, Landspitali – University Hospital & Department of Food Science, University of Iceland, Reykjavik, Iceland and 4 Center of Prenatal Care, Reykjavik Health Care Center, Reykjavik, Iceland 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 ¼ 3.32, confidence interval (CI) ¼ 1.81–6.09, Po0.001) and drinking more milk (OR ¼ 3.10, CI ¼ 1.57–6.13, P ¼ 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 ¼ 2.52, CI ¼ 1.10–5.77, P ¼ 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 ¼ 7.37, CI 4.13–13.14, Po0.001). Women gaining suboptimal weight gave birth to lighter children (Po0.001) and had shorter gestation (P ¼ 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. International Journal of Obesity (2006) 30, 492–499. doi:10.1038/sj.ijo.0803184; published online 6 December 2005 Keywords: pregnancy; maternal weight gain; energy intake; milk; sweets; birth outcome Introduction Weight gain during pregnancy is one of the main factors related to birth outcome, 1,2 with birth weight being highly correlated to maternal weight gain. 3,4 Studies have identified factors influencing gestational weight gain such as prepreg- nancy body mass index (BMI), height, age, parity, smoking, duration of gestation and fetal sex. 5–9 Few studies have investigated nutritional factors related to weight gain during pregnancy as well as the consequent birth size para- meters, 10,11 and some have focused on dietary factors related to birth outcome only. 12–15 Total energy intake (EI) has been related to maternal weight gain, but with regard to the association of the macronutrients with maternal weight gain and birth outcome, data are inconclusive or scarce. 11,16–18 Adequate weight gain is important for optimal perinatal outcome, but high weight gain in pregnancy has been related to gestational complications (i.e., hypertension, diabetes and pre-eclampsia), complications in delivery 1,4,19–21 and macrosomia 22 and low weight gain to retarded fetal growth and preterm birth. 19 With increasing rates of obesity in the world, 23 especially among women, 24–26 it is a commonly held notion that excessive pregnancy weight gain contributes to the increased rates of obesity in women. 3,27–30 Received 15 April 2005; revised 2 October 2005; accepted 7 October 2005; published online 6 December 2005 Correspondence: Dr L Steingrimsdottir, Public Health Institute of Iceland, Laugavegur 116, Reykjavik IS-101, Iceland. E-mail: naering@simnet.is International Journal of Obesity (2006) 30, 492–499 & 2006 Nature Publishing Group All rights reserved 0307-0565/06 $30.00 www.nature.com/ijo