Many care providers promote restricting prenatal weight gain in "obese" women with the hopes that this will reduce obesity in their offspring.
Keep fat women from gaining weight in pregnancy and you will keep their children from being fat, right? "Do it for the children!" is the guilt-inducing line.
Here is a recent study that shows that prenatal weight gain restriction does not have any effect on child size.
Child Obes. 2016 Jun;12(3):162-70. doi: 10.1089/chi.2015.0177. Epub 2016 Mar 23. Effects of a Gestational Weight Gain Restriction Program for Obese Pregnant Women: Children's Weight Development during the First Five Years of Life. Claesson IM1, Sydsjö G1, Olhager E2, Oldin C3, Josefsson A1. PMID: 27007580
BACKGROUND: Maternal prepregnancy obesity (BMI ≥30 kg/m(2)) and excessive gestational weight gain (GWG) have shown a strong positive association with a higher BMI and risk of obesity in the offspring. The aim of this study is to estimate the effect of a GWG restriction program for obese pregnant women on the children's BMI at 5 years of age and weight-for-length/height (WL/H) development from 2 months of age until 5 years of age. METHODS: This was a follow-up study of 302 children (137 children in an intervention group and 165 children in a control group) whose mothers participated in a weight gain restriction program during pregnancy. RESULTS: BMI at five years of age did not differ between girls and boys in the intervention and control group. The degree of maternal GWG, <7 kg or ≥7 kg, did not affect the offspring's WL/H. Compared with Swedish reference data, just over half of the children in both the intervention and control group had a BMI within the average range, whereas slightly more than one-third of the children had a higher BMI. CONCLUSION: Despite a comprehensive gestational intervention program for obese women containing individual weekly visits and opportunity to participate in aqua aerobic classes, there were no differences between BMI or weight development among the offspring at 5 years of age in the intervention and control group.