%0 Journal Article %T Prepregnancy Physical Activity in relation to Offspring Birth Weight: A Prospective Population-Based Study in Norway〞The HUNT Study %A Silje Krogsgaard %A Sigridur L. Gudmundsdottir %A Tom I. L. Nilsen %J Journal of Pregnancy %D 2013 %I Hindawi Publishing Corporation %R 10.1155/2013/780180 %X Background. The objective was to examine the association between prepregnancy physical exercise and offspring birth weight and to assess the combined association of pre-pregnancy body mass index (BMI) and physical exercise on birth weight. Methods. The study included 2,026 women aged 20每39 years participating in the Norwegian HUNT study and linked with the Medical Birth Registry. We calculated mean differences in birth weight and odds ratios (ORs) for a macrosomic infant (i.e., birth weight ˋg) using linear and logistic regression analysis. Results. There was no clear association between leisure time physical exercise and mean birth weight. Women who reported no exercise had reduced risk of a macrosomic infant (OR, 0.6; 95% confidence interval (CI), 0.4每0.9) compared to women with a high exercise level. Overweight ( ˋkg/m2) was associated with an OR of 1.9 (95% CI, 1.2每2.9) for a macrosomic infant among women who reported low exercise levels, whereas the OR was 1.2 (95% CI, 0.8每1.8) among women with higher exercise levels. Conclusion. There was some evidence that women who reported no exercise before pregnancy had lower risk for a macrosomic infant than women who exercised. Pre-pregnancy BMI was positively associated with birth weight and risk of macrosomia but only among the least active women. 1. Introduction The proportion of women giving birth to large infants has increased around the world [1, 2], most likely because of the rising rates of maternal overweight and obesity [3每7]. Whereas consequences of low birth weight may include infant mortality and morbidity [8], high birth weight has been related to increased risk for caesarean section, chorioamnionitis, fourth degree perinatal lacerations, postpartum haemorrhage, shoulder dystocia [9每11], and low Apgar score [12]. Additionally, high birth weight has been positively associated with obesity [13] and type 2 diabetes [14] in adulthood. Previous studies have reported that physical activity in pregnancy is related to foetal growth rate and birth weight [15, 16], and that physically active women have a reduced risk of delivering a large infant [17, 18], possibly by increased insulin sensitivity [6]. However, not all studies have reported consistent inverse associations between physical activity in pregnancy and birth weight [19每22]. Although women who exercise regularly before pregnancy are more likely to continue to exercise during pregnancy [23每25], few studies have examined the associations between prepregnancy physical activity and birthweight, and the results have been inconsistent [18, 20, 26, %U http://www.hindawi.com/journals/jp/2013/780180/