There is not enough evidence to recommend any intervention for preventing excessive weight gain during pregnancy, due to the significant methodological limitations of included studies and the small observed effect sizes. More high-quality randomised controlled trials with adequate sample sizes are required to evaluate the effectiveness of potential interventions.
A randomized trial of the effects of dietary counseling on gestational weight gain and glucose metabolism in obese pregnant women.
Can gestational weight gain in obese women be restricted by 10-h dietary consultations and does this restriction impact the pregnancy-induced changes in glucose metabolism?
                A randomized controlled trial with or without restriction of gestational weight gain to 6-7 kg by ten 1-h dietary consultations.
                Fifty nondiabetic nonsmoking Caucasian obese pregnant women were randomized into intervention group (n=23, 28+/-4 years, prepregnant body mass index (BMI) 35+/-4 kg m(-2)) or control group (n=27, 30+/-5 years, prepregnant BMI 35+/-3 kg m(-2)).
                The weight development was measured at inclusion (15 weeks), at 27 weeks, and 36 weeks of gestation. The dietary intakes were reported in the respective weeks by three 7-day weighed food records and blood samples for analyses of fasting s-insulin, s-leptin, b-glucose, and 2-h b-glucose after an oral glucose tolerance test were collected.
                The women in the intervention group successfully limited their energy intake, and restricted the gestational weight gain to 6.6 kg vs a gain of 13.3 kg in the control group (P=0.002, 95% confidence interval (CI): 2.6-10.8 kg). Both s-insulin and s-leptin were reduced by 20% in the intervention group compared to the control group at week 27, mean difference: -16 pmol l(-1) (P=0.04, 95% CI: -32 to -1) for insulin and -23 ng ml(-1) (P=0.004, 95% CI: -39 to -8) for leptin. At 36 weeks of gestation, the s-insulin was further reduced by 23%, -25 pmol l(-1) (-47 to -4, P=0.022) and the fasting b-glucose were reduced by 8% compared with the control group (-0.3 mmol l(-1), -0.6 to -0.0, P=0.03).
                Restriction of gestational weight gain in obese women is achievable and reduces the deterioration in the glucose metabolism.