['To compare the gestational weight gain and adverse perinatal outcomes in urban Mexican women with prepregnancy overweight or obesity, under an early intensive obstetric and nutrition program versus women with prepregnancy normal weight.', 'A cohort of 546 pregnant women with prepregnancy normal weight (n = 201, NW), overweight (n = 171, OW) or obesity (n = 174, OB), ≤13 weeks of gestation and a singleton pregnancy. OW and OB groups were under early intensive obstetric and nutritional care and NW group was under routine prenatal care. Miscarriage, hypertensive disorders, premature rupture of membranes, preterm birth, stillbirth, gestational diabetes mellitus (GDM) and large- or small-for-gestational-age newborns, were compared between groups.', 'Weight gain was smaller in OB than in OW or NW (mean ± SD): 6.1 ± 4.4, 9.5 ± 5.1, 10.3 ± 5.4 kg, respectively (p < 0.001). OB women had the highest frequency of GDM (p < 0.001), lack of spontaneous labor (p < 0.001) and preeclampsia (p < 0.001), but no other between-group differences existed.'] Is early intensive obstetric and medical nutrition care associated with decreased prepregnancy obesity impact on perinatal outcomes?